Download Anna University B.Tech (Bachelor of Technology) Mech Engg.(Mechnical Engineering) 3rd Sem Computer Aided Machine Drawing CAMD Lab Manual Question Paper.
We rely on ads to keep our content free. Please consider disabling your ad blocker or whitelisting our site. Thank you for your support!
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges)trim>/Undo: (pick the line(s) that need to be trimmed).
Creating Layers
LAYER: Creates named drawing layers and assigns color and line type properties to those layers.
Command: LAYER (enter)
A Layer & Line type Properties dialog box will be displayed. To add a new layer, pick the new
button. A new layer listing appears, using a default name of Layer1. The layer name can be changed
by highlighting the layer name. Colors and Line types can be assigned to each new layer by picking
the color box to assign a color and picking the line type box to assign a line type.
Standard AutoCAD colors
1 = Red 2 = Yellow 3 = Green 4 = Cyan
5 = Blue 6 = Magenta 7 = White
30 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Standard AutoCAD line types
Hidden2 = hidden lines
Center2 = center lines
Phantom2 = phantom or cutting-plane lines
Construction Commands
ARRAY (AR): Makes multiple copies of selected objects in a rectangular or circular pattern
Command: ARRAY (enter)
Select objects or Window or Last: (select object to array)
Rectangular or Polar array (R/P)
Center point of array: (pick the point around which to form the array)
Angle to fill (+=CCW, -=Cw) <360>: (enter)
COPY (CO): Draws a copy of selected objects.
Command: COPY (enter)
Select objects or Window or Last: (select objects to be copied)
Base point or displacement: (pick a point on the object to be use as a reference point)
Second point of displacement: (pick a point which represents the new location of the copied object)
MIRROR(MI): Makes mirror images of existing objects.
Command: MIRROR (enter)
Select objects or Window or Last: (select objects to be mirrored)
First point of mirror line: (pick a point on top of the mirror line)
Second point: (pick a point on the bottom of the mirror line) Delete old objects?
MOVE(M): Moves designated entities to another location.
Command: MOVE (enter)
Select objects or Window or Last: (select objects to move)
Base point or displacement: (pick a point on the object to be use as a reference point)
Second point of displacement: (pick a point which represents the new location of the object)
OFFSET (O): Constructs an entity parallel to another entity at a specified distance. Offset can be used
with lines, circles, arcs, and polylines.
Command: OFFSET (enter)
Offset distance or Through
Select object to offset: (select object to offset)
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
55 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Knuckle Joint
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
55 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Knuckle Joint
56 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of knuckle joint had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given knuckle joint using standard CAD software.
Application:
1. Automobile
1. In what situation flexible coupling is used?
2. What are the applications of knuckle joint?
3. Why is taper given to key? Why is taper given only on one side?
4. Knuckle Joint is used to connect two rods _____________
5. Knuckle joint can?t be used for ___________________
Viva-voce
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
55 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Knuckle Joint
56 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of knuckle joint had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given knuckle joint using standard CAD software.
Application:
1. Automobile
1. In what situation flexible coupling is used?
2. What are the applications of knuckle joint?
3. Why is taper given to key? Why is taper given only on one side?
4. Knuckle Joint is used to connect two rods _____________
5. Knuckle joint can?t be used for ___________________
Viva-voce
57 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.11 3D ASSEMBLY OF SOCKET AND SPIGOT JOINT
Aim:
To create various parts of socket and spigot joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This joint is used to connect two circular rods and subjected to axial loads. For this purpose, the ends of the rods
are shaped suitably to form a socket at one end while the other rod end as a spigot and slots are made. The given
figure shows the details of a socket and spigot joint. The spigot end of the rod 2 is inserted into the socket end of the
rod 1. After aligning the socket and spigot ends, the cotter 3 is driven-in, forming the joint.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
55 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Knuckle Joint
56 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of knuckle joint had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given knuckle joint using standard CAD software.
Application:
1. Automobile
1. In what situation flexible coupling is used?
2. What are the applications of knuckle joint?
3. Why is taper given to key? Why is taper given only on one side?
4. Knuckle Joint is used to connect two rods _____________
5. Knuckle joint can?t be used for ___________________
Viva-voce
57 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.11 3D ASSEMBLY OF SOCKET AND SPIGOT JOINT
Aim:
To create various parts of socket and spigot joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This joint is used to connect two circular rods and subjected to axial loads. For this purpose, the ends of the rods
are shaped suitably to form a socket at one end while the other rod end as a spigot and slots are made. The given
figure shows the details of a socket and spigot joint. The spigot end of the rod 2 is inserted into the socket end of the
rod 1. After aligning the socket and spigot ends, the cotter 3 is driven-in, forming the joint.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
58 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Socket and Spigot Joint
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
55 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Knuckle Joint
56 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of knuckle joint had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given knuckle joint using standard CAD software.
Application:
1. Automobile
1. In what situation flexible coupling is used?
2. What are the applications of knuckle joint?
3. Why is taper given to key? Why is taper given only on one side?
4. Knuckle Joint is used to connect two rods _____________
5. Knuckle joint can?t be used for ___________________
Viva-voce
57 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.11 3D ASSEMBLY OF SOCKET AND SPIGOT JOINT
Aim:
To create various parts of socket and spigot joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This joint is used to connect two circular rods and subjected to axial loads. For this purpose, the ends of the rods
are shaped suitably to form a socket at one end while the other rod end as a spigot and slots are made. The given
figure shows the details of a socket and spigot joint. The spigot end of the rod 2 is inserted into the socket end of the
rod 1. After aligning the socket and spigot ends, the cotter 3 is driven-in, forming the joint.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
58 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Socket and Spigot Joint
59 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of socket and spigot joint had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given socket and spigot joint using standard CAD
software.
Application:
1. Automobile
1. What is socket?
2. What is spigot?
3. What is meant by cotter?
4. Why in a cotter joint the cotter is kept weakest?
5. State the advantages of cotter joint.
6. Why taper is provided on cotter?
7. How much taper is provided on cotter?
Viva-voce
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
55 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Knuckle Joint
56 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of knuckle joint had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given knuckle joint using standard CAD software.
Application:
1. Automobile
1. In what situation flexible coupling is used?
2. What are the applications of knuckle joint?
3. Why is taper given to key? Why is taper given only on one side?
4. Knuckle Joint is used to connect two rods _____________
5. Knuckle joint can?t be used for ___________________
Viva-voce
57 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.11 3D ASSEMBLY OF SOCKET AND SPIGOT JOINT
Aim:
To create various parts of socket and spigot joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This joint is used to connect two circular rods and subjected to axial loads. For this purpose, the ends of the rods
are shaped suitably to form a socket at one end while the other rod end as a spigot and slots are made. The given
figure shows the details of a socket and spigot joint. The spigot end of the rod 2 is inserted into the socket end of the
rod 1. After aligning the socket and spigot ends, the cotter 3 is driven-in, forming the joint.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
58 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Socket and Spigot Joint
59 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of socket and spigot joint had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given socket and spigot joint using standard CAD
software.
Application:
1. Automobile
1. What is socket?
2. What is spigot?
3. What is meant by cotter?
4. Why in a cotter joint the cotter is kept weakest?
5. State the advantages of cotter joint.
6. Why taper is provided on cotter?
7. How much taper is provided on cotter?
Viva-voce
60 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.12 3D ASSEMBLY GIB AND COTTER JOINT
Aim:
To create various parts of gib and cotter joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Gib and cotter joints are used for rods of square or rectangular cross section, the ends of one rod fits the end of
the other rod which is made in the form of a strap. A gib is used along with the cotter to make this joint. Gib is likely a
cotter but with two gib heads at its ends. The thickness of the gib and cotter are same.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
55 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Knuckle Joint
56 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of knuckle joint had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given knuckle joint using standard CAD software.
Application:
1. Automobile
1. In what situation flexible coupling is used?
2. What are the applications of knuckle joint?
3. Why is taper given to key? Why is taper given only on one side?
4. Knuckle Joint is used to connect two rods _____________
5. Knuckle joint can?t be used for ___________________
Viva-voce
57 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.11 3D ASSEMBLY OF SOCKET AND SPIGOT JOINT
Aim:
To create various parts of socket and spigot joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This joint is used to connect two circular rods and subjected to axial loads. For this purpose, the ends of the rods
are shaped suitably to form a socket at one end while the other rod end as a spigot and slots are made. The given
figure shows the details of a socket and spigot joint. The spigot end of the rod 2 is inserted into the socket end of the
rod 1. After aligning the socket and spigot ends, the cotter 3 is driven-in, forming the joint.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
58 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Socket and Spigot Joint
59 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of socket and spigot joint had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given socket and spigot joint using standard CAD
software.
Application:
1. Automobile
1. What is socket?
2. What is spigot?
3. What is meant by cotter?
4. Why in a cotter joint the cotter is kept weakest?
5. State the advantages of cotter joint.
6. Why taper is provided on cotter?
7. How much taper is provided on cotter?
Viva-voce
60 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.12 3D ASSEMBLY GIB AND COTTER JOINT
Aim:
To create various parts of gib and cotter joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Gib and cotter joints are used for rods of square or rectangular cross section, the ends of one rod fits the end of
the other rod which is made in the form of a strap. A gib is used along with the cotter to make this joint. Gib is likely a
cotter but with two gib heads at its ends. The thickness of the gib and cotter are same.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
61 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Gib and Cotter Joint
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
55 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Knuckle Joint
56 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of knuckle joint had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given knuckle joint using standard CAD software.
Application:
1. Automobile
1. In what situation flexible coupling is used?
2. What are the applications of knuckle joint?
3. Why is taper given to key? Why is taper given only on one side?
4. Knuckle Joint is used to connect two rods _____________
5. Knuckle joint can?t be used for ___________________
Viva-voce
57 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.11 3D ASSEMBLY OF SOCKET AND SPIGOT JOINT
Aim:
To create various parts of socket and spigot joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This joint is used to connect two circular rods and subjected to axial loads. For this purpose, the ends of the rods
are shaped suitably to form a socket at one end while the other rod end as a spigot and slots are made. The given
figure shows the details of a socket and spigot joint. The spigot end of the rod 2 is inserted into the socket end of the
rod 1. After aligning the socket and spigot ends, the cotter 3 is driven-in, forming the joint.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
58 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Socket and Spigot Joint
59 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of socket and spigot joint had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given socket and spigot joint using standard CAD
software.
Application:
1. Automobile
1. What is socket?
2. What is spigot?
3. What is meant by cotter?
4. Why in a cotter joint the cotter is kept weakest?
5. State the advantages of cotter joint.
6. Why taper is provided on cotter?
7. How much taper is provided on cotter?
Viva-voce
60 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.12 3D ASSEMBLY GIB AND COTTER JOINT
Aim:
To create various parts of gib and cotter joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Gib and cotter joints are used for rods of square or rectangular cross section, the ends of one rod fits the end of
the other rod which is made in the form of a strap. A gib is used along with the cotter to make this joint. Gib is likely a
cotter but with two gib heads at its ends. The thickness of the gib and cotter are same.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
61 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Gib and Cotter Joint
62 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of gib and cotter joint had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given gib and cotter joint using standard CAD
software.
Application:
1. Connect piston rod in cross head
2. Bicycle to connect pedal to sprocket wheel
1. What is the function of gib and cotter joint?
2. Name the components of gib and cotter joint.
3. State the applications of cotter joints.
4. Name the materials used for gib and cotter.
5. Name the material used for rod and fork.
Viva-voce
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/
Change what property (Color/Elev/ Layer/L Type/Thickness)? (Type Layer) New Layer:
(enter new layer name and press enter)
ERASE (E): Erases entities from the drawing.
Command: ERASE (enter)
Select objects or Window or Last: (Select objects to be erased and press enter when finished)
TRIM (TR): Trims a line to end precisely at a cutting edge.
Command: Trim (enter)
Select cutting edge(s)... Select Objects (pick the line which represents the cutting edge of line in
which objects will be trimmed to)(press enter when finished selecting cutting edges): (pick the first line) S
elect second line: (pick the second line)
CHAMFER (CHA): Changes any corner to an angled corner.
Command: CHAMFER
Polyline/Distance/Angle/Trim/Method/ < Select first line > : (pick the first line)
Select second line: (pick the second line)
OSNAP (F3): Instantly locates exact points relative to existing objects (points).
Object Snap Modes: Endpoint, Midpoint, Center, Quadrant, Intersection, Insertion, Perpendicular, Tangent, Nearest,
Node, and None.
Placing lettering on a drawing
TEXT (M TEXT):Draws text characters of any size.
Command: TEXT (enter)
Justify/Style/
Height (0) (enter the height of the lettering)
Rotation Angle (0) (enter)
Text: (enter the desired lettering) (enter)
Summary of Options
Justify Justifies text according to the alignment options
Style Enters a new text style
Null reply Enters a new line of text below the previous text.
32 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Alignment Abbreviation Orientation
Aligned A Aligns text between two points. Text height will adjust automatically
Fit F Fits text between two points. Text height will not change
Centered C Centers text at the baseline of a specified point
Middle M Centers text horizontally and vertically at the baseline of a specified point.
Right R Justify text at the baseline of a specified point
Top Left TL Left Justifies text at the top of text
Top Center TC Centers text at the top of text
Top Right TR Right justifies text at the top to text
Middle Left ML Left justifies text at the middle of text
Middle Center MC Centers text both horizontally and vertically at the middle of the text
Middle Right MR Right justifies text at the middle of text
Bottom Left BL Left justifies text at the bottom of text
Bottom Center BC Centers text a the bottom of text
Bottom Right BR Right justifies text at the bottom of text
Crosshatching a drawing
BHATCH: Allows the user to crosshatch areas of a section view.
Command: BHATCH (enter)
The Boundary Hatch dialogue Box will be displayed. Select the Hatch Options box. The
Hatch Options box will be displayed. Select the Patterns box.
The Choose Hatch Pattern box will be displayed. Select the desired hatch pattern.
The Hatch Options box will be displayed again. We can select a scale and rotation angle for the
crosshatch pattern. Select the OK box when finished.
The Boundary Hatch dialogue box will be displayed again. Select the Pick Points box. When
prompted select the internal point of the area to be crosshatched. Press the enter key when finished.
The Boundary Hatch dialog box will be displayed again. Select the Apply box to add the crosshatching to
the drawing.
33 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.03 INTRODUCTION TO MODELLING SOFTWARE PRO-E
Introduction:
Pro-E is a high end cad package. Pro-E is a parametric solid model. It was developed by parametric technology
corporation. It is suite of programs that are used in design analysis and manufacturing of a virtually unlimited
range of products.
Feature based:
Pro-E is a feature based solid modeling tool. It builds the model using individual building blocks one at a time.
Designers can think at a high level and leave all the low level geometry details, for Pro-E to figure out.
Associative:
We can use Pro-E to document model by creating parts, assemblies and drawing all these functions are really
associative.
Parametric:
Parametric means that the physical shape of the part is driven by the values assigned to the attributes of its
features.
Solid modeling:
Solid modeling means that the computer model we create is able to contain all the information that a real solid
object would have the material.
Parent - child Relationship:
An important aspect to feature based modeling in Pro-E is the concept of modeling in pro-E parent - child
relationship.
Datum plane:
A datum plane representation of an infinite large power surface area of a user defined orientation and location
that are continuously adjusted automatically to be slightly larger than the object.
Plane-Insert-Datum-Plane:
Default method creates three mutually perpendicular datum planes intersecting at the origin at the default
coordinate system. These three planes represents XY, YZ & ZX planes are named as follows:
DTM1 ? represents YZ plane
DTM2 ? represents ZX plane
DTM3 ? represents XY plane
Datum axis:
It can be used as a reference for features creation. It is particularly useful for making datum planes placing items
concentrically and creating radial patterns.
34 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Part modeling:
Pro-E is a feature based modeling software. Features in Pro-E are of two kinds. Place features extrude,
revolve, sweep and blend are examples of sketched features.
Sketches features:
Protrusion features:
Protrusion is the method of adding a solid material of the method. Pro-E provides the following basic
methods of adding material to a method.
Extrude: creates a solid feature by extruding a section named to the section.
Revolve: creates a solid surface by revolving a section about an axis.
Sweep: creates a solid feature by sweeping a section about a path.
Blend: creates a solid feature by blending various cross sections at various levels.
Extrusion:
Features ? create ? solid ? protrusion ? extrude
Attribute types:
One side: Adds the material in one side of the cross section only.
Both sides: Adds the material on both sides of the cross section.
Defining sketching plane: We have to specify the sketch plane to draw the cross section.
Direction of feature creation:
Once the direction of extrusion is defined Pro-E will promote for orienting the sketch plane. Orientation plane
can lie horizontally or vertically in the section view sketch plane once the orientation plane is defined, tools
needed for sketching the cross section will be provided by Pro-E.
Sketch reference:
Pro-E automatically selects two mutually perpendicular lines which are normal to the sketching plane as
horizontal and vertical reference for dimensioning and constraining the sketch.
Extrusion depth:
Blind: Enter a dimension for the feature depth. We can then control the feature depth by changing the depth
dimension
Through next: Terminate the features at the next part surface
Through all: The new surface intersects all surfaces
Rib: Feature ? create ? solid ? rib
A rib is a special type of protrusion designed to create a thin wall or web to support two surface. All straight
holes are created with constant diameter. A hole from feature always removes material from our model.
35 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Round:
Features ? create ? solid ? round
It creates smooth transition with circular or profile between adjacent surface. An edge round smoothness the
hard edges between adjacent surface.
Sweep:
Feature ? create ? solid ? protrusion ? sweep
A sweep is creating by defining two sections. The section is the trajectory and the second cross section.
Sweep can be used on for protrusion cut and slots.
Blend:
Feature ? create ? solid ? protrusion ? blend
Blending is the method of defining a volume by connecting series of at least two planner sections together, at
their edges with transitional surface.
Assembly creation:
Assembly mode in Pro-E enable us to place component parts and use assemblies together to form assemblies
as well as to design parts based on how they should fit together.
Mate:
Selected surface point in opposite direction and become coplanar.
Mate offset:
Selected surface point in opposite direction and are offset by specific value.
Align:
Selected surface point in opposite direction and become coplanar axis may be co-axial with the align command.
Align offset:
Selected surface point in opposite direction and are offset by a specific value which is to be modified to
provide design flexibility.
Orient:
Make the two surface of revolution co-axial.
36 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.04 2D DRAFTING OF PLUMMER BLOCK BEARING
Aim:
To create a 2D model of plummer block bearing by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
37 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
38 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of plummer block bearing is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in automobile.
Application:
1. R & D
2. Automobile
1. What is meant by Auto CAD?
2. What is the difference between CAD and CADD?
3. What are the applications of CAD?
4. Define ? Absolute Coordinate System
5. Define ? Polar Coordinate System
6. What is a hatch pattern?
7. What is the advantage of plummer block bearing over simple bushed bearing?
Viva-voce
39 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.05 2D DRAFTING OF NON-RETURN VALVE
Aim:
To create a 2D model of non-return valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
40 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Non-return valve (light duty)
41 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of non-return valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in pumps.
Application:
1. Pumps
2. Industrial processes
1. What are the advantages of CAD?
2. What is a non return valve?
3. Name the components of non return valve.
4. Write the applications of non return valve.
5. Name the editing commands
Viva-voce
42 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.06 2D DRAFTING OF SAFETY VALVE
Aim:
To create a 2D model of safety valve by using standard CAD software
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Auto CAD
Procedure:
1. Set the units to mm.
2. Using LIMITS Command set the limits to 420,297.
3. Using ZOOM Command fit the drawing to window.
4. Draw the part using LINE command and extrude it using REGION, EXTRUDE commands.
5. Draw the front view, top view and side view using drawing commands.
6. Detail the drawing as per dimensions.
43 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
44 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the 2D model of safety valve is created by using standard CAD software
Outcome:
From this experiment, students will be able to create the detailed drawings which is used in boilers.
Application:
1. R & D
2. Boilers
1. What is safety valve?
2. Name the types of safety valves.
3. Name the components of safety valve.
4. Write the applications of safety valve.
5. Name the utility commands
6. Name the types of modeling in CAD.
Viva-voce
45 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.07 3D ASSEMBLY OF FLANGE COUPLING
Aim:
To create various parts of flange coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Couplings are used to join two shafts so that they act as a single unit during rotation and power can be
transmitted from one shaft to the other. The protected flanged coupling is a rigid shaft coupling, the axes of the
shafts being collinear. The flanges 2 and 3 are mounted at the ends of two shafts 1 by means of keys 5. Later, the
two flanges are connected to each other by means of bolts with nuts 4. In this rigid coupling, the bolt heads and nuts
are locked in the annular recesses provided on the flange and so are not exposed. Hence, the name protected
flanged coupling.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
46 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Flange Coupling
47 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of flange coupling had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment. Students will be able to assemble the given flange coupling using standard CAD software.
Application:
1. Automobile
2. Transmission systems
1. Name the components used in flange coupling.
2. What is the function of flange coupling?
3. What are the materials used for making flange coupling?
4. Define ? Coupling
5. Name the different types of couplings.
Viva-voce
48 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.08 3D ASSEMBLY OF UNIVERSAL COUPLING
Aim:
To create various parts of universal coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a rigid coupling and is used to connect two shafts, whose axes intersect if extended. The given figure
shows the details of universal coupling. The forks 2 are mounted at the ends of two shafts 1, making use of sunk
keys 6. The central block 3, having two arms at right angle to each other, is placed between the forks and connected
to both of them by using pins 4 and collars 5. A taper pin is used to keep the pins 4 in position. During rotation of
shafts, the angle between them can be varied.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
49 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Universal Coupling
50 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of universal coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given universal coupling using standard CAD
software which is used in automobile.
Application:
1. Automobile
1. Define ? Coupling
2. What are the different types of couplings?
3. What is meant by universal coupling?
4. What are the components used in universal coupling?
5. What type of keyway is used in universal coupling?
Viva-voce
51 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.09 3D ASSEMBLY OF OL D HAM ? S COUPLING
Aim:
To create various parts of Oldham?s coupling and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This coupling is known as a non-aligned coupling and is used to connect two parallel shafts, whose axes are at a
small distance apart. The given figure shows various parts of a Oldham?s coupling. The two flanges 1 are mounted
on the ends of shafts 3 by means of sunk keys 4. The flanges are having rectangular slots in them. These flanges
are set such that, the slots in them are at right angle to each other. The circular disc 2 is now positioned in between
them so that the projections in the circular disc, enter into the corresponding slots of the flanges. During rotation of
the shafts, the central disc slides in the slots of the flanges.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
52 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Oldham?s Coupling
53 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of Oldham?s coupling had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given Oldham?s coupling using standard CAD
software.
Application:
1. Automobile
1. Define ? Coupling
2. What is oldham?s coupling?
3. What are the advantages of oldham?s coupling?
4. What are the components used in oldham?s coupling?
5. What are the materials used in oldham?s coupling?
Viva-voce
54 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.10 3D ASSEMBLY OF KNUCKLE JOINT
Aim:
To create various parts of knuckle joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This is a pin joint and is used to connect two circular rods subjected to axial loads. Compared to a socket and
spigot joint, wherein the axes of both the rods should be in the same plane; in the knuckle joint, one of the rods can
be swiveled through some angle about the connecting pin, i.e., the axes of the two rods could be inclined to each
other. The given figure shows the details of a knuckle joint. The eye end of the rod 2 is inserted into the fork end 1 of
the other rod. Then, pin 3 is inserted through the holes in the ends of the rods and held in position by the collar 4 and
taper pin 5.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
55 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Knuckle Joint
56 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of knuckle joint had been created and assembled by using standard CAD software
Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given knuckle joint using standard CAD software.
Application:
1. Automobile
1. In what situation flexible coupling is used?
2. What are the applications of knuckle joint?
3. Why is taper given to key? Why is taper given only on one side?
4. Knuckle Joint is used to connect two rods _____________
5. Knuckle joint can?t be used for ___________________
Viva-voce
57 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.11 3D ASSEMBLY OF SOCKET AND SPIGOT JOINT
Aim:
To create various parts of socket and spigot joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
This joint is used to connect two circular rods and subjected to axial loads. For this purpose, the ends of the rods
are shaped suitably to form a socket at one end while the other rod end as a spigot and slots are made. The given
figure shows the details of a socket and spigot joint. The spigot end of the rod 2 is inserted into the socket end of the
rod 1. After aligning the socket and spigot ends, the cotter 3 is driven-in, forming the joint.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
58 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Socket and Spigot Joint
59 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of socket and spigot joint had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given socket and spigot joint using standard CAD
software.
Application:
1. Automobile
1. What is socket?
2. What is spigot?
3. What is meant by cotter?
4. Why in a cotter joint the cotter is kept weakest?
5. State the advantages of cotter joint.
6. Why taper is provided on cotter?
7. How much taper is provided on cotter?
Viva-voce
60 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.12 3D ASSEMBLY GIB AND COTTER JOINT
Aim:
To create various parts of gib and cotter joint and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
Gib and cotter joints are used for rods of square or rectangular cross section, the ends of one rod fits the end of
the other rod which is made in the form of a strap. A gib is used along with the cotter to make this joint. Gib is likely a
cotter but with two gib heads at its ends. The thickness of the gib and cotter are same.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
61 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Details of Gib and Cotter Joint
62 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Result:
Thus the given various part of gib and cotter joint had been created and assembled by using standard CAD
software Pro-E.
Outcome:
From this experiment, Students will be able to assemble the given gib and cotter joint using standard CAD
software.
Application:
1. Connect piston rod in cross head
2. Bicycle to connect pedal to sprocket wheel
1. What is the function of gib and cotter joint?
2. Name the components of gib and cotter joint.
3. State the applications of cotter joints.
4. Name the materials used for gib and cotter.
5. Name the material used for rod and fork.
Viva-voce
63 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.13 3D ASSEMBLY CONNECTING ROD
Aim:
To create various parts of connecting rod and assemble them by using standard CAD software Pro-E
System configuration:
Ram : 8 GB
Processor : Core 2 Quad / Core 2 Duo
Operating system : Windows 7
Software : Pro-E Wildfire 4.0
Description:
A connecting rod is an engine component that transfers motion from the piston to the crankshaft and functions as
a lever arm. Connecting rods are commonly made from cast aluminum alloy and are designed to withstand dynamic
stresses from combustion and piston movement. The small end of the connecting rod connects to the piston with a
piston pin. The piston pin, or wrist pin, provides a pivot point between the piston and connecting rod. Spring clips, or
piston pin locks, are used to hold the piston pin in place. The big end of the connecting rod connects to the crankpin
journal to provide a pivot point on the crankshaft. Connecting rods are produces as one piece or two-piece
components. A rod cap is the removable section of a two-piece connecting rod that provides a bearing surface for
the crankpin journal. The rod cap is attached to the connecting rod with two cap screws for installation and removal
from the crankshaft.
Commands used:
Part diagram:
Extrude ? Sketch ? Sketch to dimension ? Ok
Hole ? Sketch ? given dimension ? Ok
Revolve ? Sketch plane ? Sketches ? Centerlines ? Sketch to dimension ? Ok
Assembly:
Assembly ? Set default ? Assembly according to alignment ? fully constrained ? Ok
FirstRanker.com - FirstRanker's Choice
?
DEPARTMENT OF
MECHANICAL ENGINEERING
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
III SEMESTER - R 2017
Name : _______________________________________
Register No. : _______________________________________
Section : _______________________________________
LABORATORY MANUAL
1 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
College of Engineering is committed to provide highly disciplined, conscientious and
enterprising professionals conforming to global standards through value based quality education and training.
To provide competent technical manpower capable of meeting requirements of the industry
To contribute to the promotion of academic excellence in pursuit of technical education at different levels
To train the students to sell his brawn and brain to the highest bidder but to never put a price tag on heart and soul
DEPARTMENT OF MECHANICAL ENGINEERING
Rendering the services to the global needs of engineering industries by educating students to become
professionally sound mechanical engineers of excellent caliber
To produce mechanical engineering technocrats with a perfect knowledge intellectual and hands on
experience and to inculcate the spirit of moral values and ethics to serve the society
VISION
MISSION
VISION
MISSION
2 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
1. Fundamentals
To impart students with fundamental knowledge in mathematics and basic sciences that will mould them to be
successful professionals
2. Core competence
To provide students with sound knowledge in engineering and experimental skills to identify complex software
problems in industry and to develop a practical solution for them
3. Breadth
To provide relevant training and experience to bridge the gap between theory and practice which enable them to find
solutions for the real time problems in industry and organization and to design products requiring interdisciplinary skills
4. Professional skills
To bestow students with adequate training and provide opportunities to work as team that will build up their
communication skills, individual, leadership and supportive qualities and to enable them to adapt and to work in ever
changing technologies
5. Life-long learning
To develop the ability of students to establish themselves as professionals in mechanical engineering and to create
awareness about the need for lifelong learning and pursuing advanced degrees
3 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
PROGRAMME OUTCOMES (POs)
On completion of the B.E. (Mechanical) degree, the graduate will be able
1. To apply the basic knowledge of mathematics, science and engineering
2. To design and conduct experiments as well as to analyze and interpret data and apply the same in the
career or entrepreneurship
3. To design and develop innovative and creative software applications
4. To understand a complex real world problem and develop an efficient practical solution
5. To create, select and apply appropriate techniques, resources, modern engineering and IT tools
6. To understand the role as a professional and give the best to the society
7. To develop a system that will meet expected needs within realistic constraints such as economical
environmental, social, political, ethical, safety and sustainability
8. To communicate effectively and make others understand exactly what they are trying to tell in both verbal
and written forms
9. To work in a team as a team member or a leader and make unique contributions and work with coordination
10. To engage in lifelong learning and exhibit their technical skills
11. To develop and manage projects in multidisciplinary environments
4 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381 ? COMPUTER AIDED MACHINE DRAWING LABORATORY
SYLLABUS
To make the students understand and interpret drawings of machine components
To prepare assembly drawings both manually and using standard CAD packages
To familiarize the students with Indian standards on drawing practices and standard components
To gain practical experience in handling 2D drafting and 3D modelling software systems
List of Experiments
A. Drawing standards & fits and tolerances
Code of practice for Engineering drawing BIS specifications ? welding symbols, riveted joints, keys, fasteners-
reference to hand book for the selection of standard components like bolts, nuts, screws, keys etc, - limits, fits-
tolerancing of individual dimensions-specification of fits-preparation of production drawings and reading of part
and assembly drawings, basic principles of geometric dimensioning & tolerancing
B. Introduction to 2D drafting
Drawing, editing, dimensioning, layering, hatching, block, array, detailing, detailed drawing.
Bearings- Bush bearing, plummer block
Valves-safety and non-return valves
C. 3D Geometric modelling and assembly
Sketcher-datum planes-protrusion-holes-part modelling-extrusion-revolve-sweep-loft-blend-fillet-pattern-chamfer-
round-mirror-section-assembly
Couplings ? Flange, Universal, Oldham?s, Muff, Gear couplings
Joints ? Knuckle, Gib & cotter, strap, sleeve & cotter joints
Engine parts ? piston, connecting rod, cross-head (vertical and horizontal), stuffing box, multi-plate clutch
Miscellaneous machine components ? screw jack, machine vice, tail stock, chuck, vane and gear pump
Upon completion of this course, the students will be able to follow the drawing standards, fits and tolerances and
re-create part drawings, sectional views and assembly drawings as per standards
COURSE OBJECTIVES
COURSE OUTCOMES
5 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ME8381- COMPUTER AIDED MACHINE DRAWING LABORATORY
CONTENTS
Sl. No. Name of the experiments
Page No.
1
Study of Drawing standards and fits and tolerances 6
2 Introduction to CADD 24
3 Introduction to modeling software Pro-E 33
4
2D Drafting of Plummer block bearing 36
5 2D Drafting of Non-return valves 39
6 2D Drafting of Safety valve 42
7 3D Assembly of Flange Coupling 45
8
3D Assembly of Universal Coupling 48
9 3D Assembly of Oldham?s Coupling 51
10 3D Assembly of Knuckle joint 54
11 3D Assembly of Socket and Spigot joint 57
12
3D Assembly of Gib and Cotter joint 60
13 3D Assembly of Connecting rod 63
14 3D Assembly of Piston 66
15
3D Assembly of Stuffing box
69
16
3D Assembly of Crosshead
72
17
3D Assembly of Multi plate clutch
75
18
3D Assembly of Screw jack
79
19
3D Assembly of Machine vice
82
20
3D Assembly of Tail stock
85
21
3D Assembly of Chuck
88
22
3D Assembly of Gear pump
91
ADDITIONAL EXPERIMENTS BEYOND THE SYLLABUS
23 Introduction to LS-DYNA 94
PROJECT WORK
99
6 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.01 STUDY OF DRAWING STANDARDS AND FITS AND
TOLERANCES
Aim:
To study about the drawing standards and fits and tolerance
1.1 Code of practice for Engineering Drawing
Abbrevations
Term Abbreviation Term Abbreviation
Across corners A/C
Across flats A/F
Approved APPD
Approximate APPROX
Assembly ASSY
Auxiliary AUX
Bearing BRG
Centimetre Cm
Centres CRS
Centre line CL
Centre to centre C/L
Chamfered CHMED
Checked CHD
Cheese head CH HD
Circular pitch CP
Circumference OCE
Continued CONTD
Counterbore C BORE
Countersunk CSK
Cylinder CYL
Diameter DIA
Diametral pitch DP
Dimension DIM
Drawing DRG
Equi-spaced EQUI-SP
External EXT
Maunfacture MFG
Material MATL
Maximum max.
Metre m
Mechanical MECH
Millimetre mm
Minimum min.
Nominal NOM
Not to scale NTS
Number No.
Opposite OPP
Outside diameter OD
Pitch circle PC
Pitch circle diameter PCD
Quantity QTY
Radius R
Radius in a note RAD
Reference REF
Required REQD
Right hand RH
Round RD
Screw SCR
Serial number Sl. No.
Specification SPEC
Sphere/Spherical SPHERE
Spot face SF
7 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Figure FIG.
General GNL
Ground level GL
Ground GND
Hexagonal HEX
Inspection INSP
Inside diameter ID
Internal INT
Left hand LH
Machine M/C
Square SQ
Standard STD
Symmetrical SYM
Thick THK
Thread THD
Through THRU
Tolerance TOL
Typical TYP
Undercut U/C
Weight WT
Standard Codes
Sl.No. IS-CODE DESCRIPTION
1 IS:9609-1983 Lettering on Technical Drawing
2 IS:10711-1983 Size of drawing sheets
3 IS:10713-1983 Scales for use on technical drawing
4 IS:10714-1983 General Principles of Presentation
5 IS:10715-1983 Presentation of threaded parts on technical drawing
6 IS:10716-1983 Rules for presentation of springs
7 IS:10717-1983 Conventional representation of gears on technical drawing
8 IS:11663-1986 Conventional representation of common features
9 IS:11664-1986 Folding of drawing prints
10 IS:11665-1986 Technical drawing ? Title blocks
11 IS:11669-1986 General principles of dimension on technical drawing
12 IS:11670-1986 Abbreviations for use in Technical Drawing
1.2 Welding symbols
Welding is a process of fastening the metal parts together permanently by the application of heat (fusion welds)
or pressure (pressure or forge welding) or both (resistance welding). Both ferrous (steel, cast iron) and Non-ferrous
metals (like brass copper and alloy) can be joined by welding.
8 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The various types of welding process are
a. Gas welding
b. Arc welding
Metal Arc Welding (MAW)
Gas metal Arc Welding (GMAW)
Submerged Arc Welding (SAW)
Tungsten Inert Gas Welding (TIG)
Metal Inert Gas Welding (MIG)
c. Forge Welding
d. Resistance Welding
e. Thermit Welding
f. High Energy Welding
A welding symbol may include the following elements:
1. Reference line
2. Arrow line
3. Basic weld symbol
4. Dimensions & other data
5. Supplementary symbols
6. Finish symbols
7. Tail
8. Specifications, process, or other references
9 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
The position of the arrow line with respect to the weld is of no special significance. The side of the joint on which
the arrow line is drawn is called ?arrow side?. The side of the joint remote to the arrow line is called ?other side?. The
reference line has significance on the weld side. If the weld symbol is placed BELOW the reference line, the welding
should be done in the ?ARROW SIDE?. If the weld symbol is placed ABOVE the reference line, the welding should
be done in the ?OTHER SIDE?. If the weld symbol is placed both ABOVE and BELOW the reference line, the welding
should be done in both the ?ARROW and OTHER SIDES?.
Basic Weld Symbol
The basic symbols recommended by Bureau of Indian Standards (BIS) for specifies the type of weld are shown in
the fig.
10 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
11 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.3 Riveted Joints
A riveted joint is a permanent type of fastener used to join the metal plates or rolled steel sections together.
Riveted joints are extensively used in structural works such as bridges and roof trusses and in the construction of
pressure vessels such as storage tanks, boilers, etc. Although welded joints are best suited to several of these
applications than the riveted joints, however, riveted joints are ideal in cases where the joints will be subjected to
pronounced vibrating loads. Riveted joints are also used when a non-metallic plate and a metallic plate are to be
connected together. They are also used when the joints are not expected to be heated while joining as in welding,
which may cause warping and tempering of the finished surfaces of the joints.
The disadvantage of riveted joints are: (i) more metal is removed while making of the holes, which weakens the
working cross sections along the line of the rivet holes, and (ii) weight of the rivets increases the weight of the
riveted members.
A rivet is a round rod made either from mild steel or non-ferrous materials such as, copper, aluminium, etc., with a
head is, and formed at one end during its manufacture and its tail end being slightly tapered. The length of the
shank of the rivet must be sufficient enough to accommodate the connection plates and provide enough material for
forming a head at its shank end. In general, the shank of the rivet will be equal to sum of the thickness of the
connecting plates plus 1.5 to 1.7 times the diameter of the rivet. If,
? = length of the shank of the rivet
d = diameter of rivet
t = thickness of each of the connecting plates
then, ? = ? + (1.5 ? 1.7)?
Various types of rivet heads for the use in general engineering work and boiler work as recommended by the
Bureau of Indian Standards. The different proportions of these rivet heads are given in terms of the nominal
diameter d of the rivet. The rivet head to be used for general purposes for diameter below 12 mm are specified in
the Indian Standard code IS:2155-1962 and for diameters between 12 and 48 mm are specified in the Indian
Standard code IS:1929-1961. The rivet heads to be used for boiler work are specified in the Indian Standard code
IS: 1928-1961. The rivet heads to be used for ship building are specified in the Indian Standard code IS: 4732-
1968.
12 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Types of rivet heads
1.4 Screw Threads, Keys and Fasteners
Screw Threads
A screw thread is a functional element used on bolt, stud, set screw, nut or any other threaded piece or
component. Screw thread is a helical groove on a cylinder surface (outer side or inner side). Its function is to
transform the input motion of rotation into output motion of translation.
If a cylindrical rod is rotated at a constant speed simultaneously if a pointed tool touching the rod moving parallel to
the axis of the rod at constant speed, the cut made by tool on the rod will be continuous and of helical form. The
helical groove is called ?thread? and the threaded rod is called a ?screw?.
Threads are cut using a lathe. Small size thread is often cut by means of a tool called die. A small size hole is
threaded by means of a tool called a tap.
The principal uses of threads are,
1. for fastening
2. for adjusting
3. for transmitting power
13 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Terms and Nomenclature
1. Crest: It is the peak edge of a screw thread that connects the adjacent flanks at the top.
2. Root: It is the bottom edge of the thread that connects the adjacent flanks at the bottom.
3. Flank or side: It is the straight portion of the surface, on either side of the screw thread.
4. Angle of the thread: It is the angle included between the sides of two adjacent threads measured on an axial
plane.
5. Depth of the thread: It is the distance between the crest and the root measured at Right angle to the axis. It is
equal to half the difference between the outer diameter and the core diameter.
6. Major diameter or outside diameter: It is the diameter of the imaginary coaxial cylinder, which would bind the
crests of an external or internal thread.
7. Minor or core or root diameter: It is the diameter of the imaginary coaxial cylinder; this would bind the roots of an
external thread or of an internal thread.
8. Pitch diameter: It is the diameter of the imaginary coaxial cylinder that can be passed so as to cut the thread, that
the width of the cut thread will be equal to the Width of the groove.
9. Pitch: It is the axial distance between a point on one thread and the corresponding Point on the next thread. It may
be indicated as the distance from crest or from root of two adjacent threads.
10. Lead: It is the distance measured parallel to the axis from a point on a thread to the corresponding point on the
same thread for one complete revolution. In other words, it is axial distance a screw advances in one revolution.
11. External thread: It is the thread on the outside surface of a member such as bolt, studs or screw.
12. Internal thread: It is the thread on the inside surface of a member such as nut or threaded hole.
13. Right hand thread: Right hand thread if turned clockwise direction advances into a threaded hole. It abbreviated
as RH.
14. Left hand thread: Left hand thread if turned anticlockwise direction advances into a threaded hole. It abbreviated
as LH.
14 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
V- THREADS
British standard whit worth thread (BSW)
This thread was introduced by Sir Joseph whit worth, and was standardized as British standard thread. It has a
thread angle of 55 degree and is rounded equally at crest and roots.
British Association threads (B.A Threads)
The angle between flanks is 47.5 degree. These threads are to supplement BSW and have fine pitches. They are
used on screws for precision work.
American standard threads (or) sellers thread
The thread angle is 60 degree and both the crests and roots are kept flat. The sellers thread has been in use in USA
and Canada.
Unified screw threads
The countries UK, U.S.A and Canada came to an arrangement for a common screw thread system with the included
angle of 60 degree and designated as unified screw thread in the year 1949. The thread on the bolt is rounded off at
the crest and root and the thread in the nut is rounded off at the root but the crest is left flat. This thread is very
important in the motor and aeroplane industries and in chemical engineering. Unified thread can be either coarse
(UNC) or fine (UNF) and unified national extra fine (UEF).
ISO Metric Thread
This is Indian standard thread for ISO (International Standard Organization). The included angle is 60
0
and the
crests are flat and roots are round. Metric threads are grouped into diameter pitch combination differentiated by the
pitch applied to specific diameters. There are coarse, constant, fine pitch series available. ISO metric threads are
defined by nominal size (Basic major diameter) and pitch both expressed in millimeters. for example, a 10mm
diameter, 1.25 pitches is expressed as M10?1.25.
SQUARE THREADS
Basic square thread
The sides of these threads are normal to the axis and parallel to each other. The depth and the thickness of the
thread are equal to half pitch. A square thread is designated by the letter SQ followed by nominal diameter pitch. For
example a square thread of nominal diameter 30mm and pitch 6mm is designated as SQ 30?6.
Acme Thread
It is a modified form of square thread. It is easier to cut and is much stronger than square thread. It has a 29
0
thread angle. This inclined sides of the thread facilitate quick and early engagement and disengagement. It
is used for power screws like lead screw of lathe, jackscrews, bench vices and valve operating screws.
15 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Buttress Thread
The profile of this thread is a combination of square and V- threads. It combines the low frictional of square and
ability to transmit power of square thread and the strength of V ? thread. It is used to transmit load in uni-direction.
These threads are used in screw press, vices.
Knuckle Thread
It is also a modification of square thread. The sharp corners of square thread are rounded off. This thread is used
where heavy wear rough use is expected. The thread can be rolled or cast easily. It is used in railway carriage
coupling screws, light bulbs and sockets, bottle caps etc and also objects made of brittle materials as glass, plastic,
porcelains etc.
Types of thread profiles
Keys
Keys are machine elements used to prevent relative rotational movement between a shaft and the parts
mounted on it, such as pulleys, gears, wheels, couplings, etc. for making the joint, keyways are cut on the surface
of the shaft and in the hub of the part to be mounted. After positioning the part on the shaft such that, both the
keyways are properly aligned, the key is driven from the end, resulting in a firm joint.
For mounting a part at any intermediate location on the shaft, first the key is firmly placed in the keyways of the
shaft and then the part to be mounted is slid from one end of the shaft, till it is fully engaged with the key.
Keys are classified into three types.
1. Saddle keys
I. flat saddle key
II. hollow saddle key
16 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
2. Sunk keys
I. taper sunk keys
II. parallel sunk keys
III. woodruff keys
3. Round keys
Types of keys
17 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Bolt and nuts
A bolt and nut in combination is a fastening device used to hold two parts together. The body of the bolt, called shank
is cylindrical in form, the head; square or hexagonal in shape, is formed by forging. Screw threads are cut on the
other end of the shank. Nuts in general are square or hexagonal in shape. The nuts with internal threads engage with
the corresponding size of the external threads of the bolt. However, there are other forms of nuts used to suit specific
requirements.
For nuts, hexagonal shape is preferred to the square one, as it is easy to tighten even in a limited space. This is
because, with only one-sixth of a turn, the spanner can be reintroduced in the same position. However, square nuts
are used when frequent loosening and tightening is required. The sharp corners on the head of bolts and nuts are
removed by chamfering.
Empirical portions of hexagonal and square head bolt & nut detail proportion
Nominal diameter d = size of bolt or nut, mm
Width across flats s = 1.5d+3 mm
Width across corners e = 2d
Thickness of bolt head k = 0.8d
Thickness of nut, n = 0.9d
Root diameter, d1 = d - (2 ? depth of thread)
Length of the bolt L = as specified
Thread length b = 2d+6mm (for l<150mm)
= 2d+12mm (for l>150mm)
Chamfer of bolt end, Z = (depth of thread ? 45
0
) or =0.1d
Chamfer angle of bolt head & nut 30
0
18 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
1.5 Limits, fits and tolerances
Limit System
Following are some of the terms used in the limit system:
Tolerance: The permissible variation of a size is called tolerance. It is the difference between the maximum and
minimum permissible limits of the given size. If the variation is provided on one side of the basic size, it is termed as
unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral
tolerance.
Limits: The two extreme permissible sizes between which the actual size is contained are called limits. The
maximum size is called the upper limit and the minimum size is called the lower limit.
Deviation: It is the algebraic difference between a size (actual, maximum, etc.) and the corresponding basic size.
Actual deviation: It is the algebraic difference between the actual size and the corresponding basic size.
Upper deviation: It is the algebraic difference between the maximum limit of the size and the corresponding basic
size.
Lower deviation: It is the algebraic difference between the minimum limit of the size and the corresponding basic
size.
Allowance: It is the dimensional difference between the maximum material limits of the mating parts, intentionally
provided to obtain the desired class of fit. If the allowance is positive, it will result in minimum clearance between the
mating parts and if the allowance is negative, it will result in maximum interference.
Basic Size: It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm
diameter shaft, then 50mm is the basic shaft size. If it has to fit into a hole, then 50 mm is the basic size of the hole.
Here, the two limit dimensions of the shaft are deviating in the negative direction with respect to the basic size and
those of the hole in the positive direction. The line corresponding to the basic size is called the zero line or line of
zero deviation.
19 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Fits
The relation between two mating parts is known as a fit. Depending upon the actual limits of the hole or shaft sizes,
fits may be classified as clearance fit, transition fit and interference fit.
Clearance Fit: It is a fit that gives a clearance between the two mating parts.
minimum clearance: It is the difference between the minimum size of the hole and the maximum size of the shaft in a
clearance fit.
maximum clearance: It is the difference between the maximum size of the hole and the minimum size of the shaft in
a clearance or transition fit.
The fit between the shaft and hole in Fig. is a clearance fit that permits a minimum clearance (allowance) value of
29.95 ? 29.90 = + 0.05 mm and a maximum clearance of + 0.15 mm.
Transition Fit: This fit may result in either interference or a clearance, depending upon the actual values of the
tolerance of individual parts. The shaft in Fig. may be either smaller or larger than the hole and still be within the
prescribed tolerances. It results in a clearance fit, when shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10
mm) and interference fit, when shaft diameter is 30.00 and hole diameter 29.95 (? 0.05 mm).
20 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Interference fit: If the difference between the hole and shaft sizes is negative before assembly; an interference fit is
obtained.
minimum interference: It is the magnitude of the difference (negative) between the maximum size of the hole and
the minimum size of the shaft in an interference fit before assembly.
maximum interference: It is the magnitude of the difference between the minimum size of the hole and the maximum
size of the shaft in an interference or a transition fit before assembly.
The shaft in fig. is larger than the hole, so it requires a press fit, which has an effect similar to welding of two parts.
The value of minimum interference is 30.25 ? 30.30 = ? 0.05 mm and maximum interference is 30.15 ? 30.40 = ? 0.25
mm.
21 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Schematic representation of fits:
Tolerance
It is impossible to make anything to an exact size, therefore it is essential to allow a definite tolerance or permissible
variation on every specified dimension.
Tolerances are specified because
? Variations in properties of the material being machined introduce errors.
? The production machines themselves may have some inherent inaccuracies.
? It is impossible for an operator to make perfect settings. While setting up the tools and workpiece on the
machine, some errors are likely to creep in.
Form variation: It is a variation of the actual condition of a form feature (surface, line) from geometrically ideal form.
Position variation: It is a variation of the actual position of the form feature from the geometrically ideal position, with
reference to another form (datum) feature.
Geometrical tolerance: Geometrical tolerance is defined as the maximum permissible overall variation of form or
position of a feature.
22 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Geometrical tolerances are used,
(i) to specify the required accuracy in controlling the form of a feature,
(ii) to ensure correct functional positioning of the feature,
(iii) to ensure the interchangeability of components, and
(iv) to facilitate the assembly of mating components.
Tolerance zone: It is an imaginary area or volume within which the controlled feature of the manufactured
component must be completely contained
Datum: It is a theoretically exact geometric reference (such as axes, planes, straight lines, etc.) to which the
tolerance features are related.
Datum feature: A datum feature is a feature of a part, such as an edge, surface, or a hole, which forms the basis for
a datum or is used to establish its location
Datum triangle: The datums are indicated by a leader line, terminating in a filled or an open triangle.
Datum letter: To identify a datum for reference purposes, a capital letter is enclosed in a frame, connected to the
datum triangle.
23 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
24 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Expt. No.02 INTRODUCTION TO CADD
CADD is an electronic tool that enables us to make quick and accurate drawings. CADD has number of
advantages over drawings created on a drawing board. Electronic drawings can be modified quite easily and can be
represented in a variety of formats.
CADD extends its power to yet another branch of engineering called computer aided manufacturing
(CAM).CADD and manufacturing program are often integrated into one system called CAD-CAM. This system
import CADD drawings into CAM program to automate the manufacturing process. When the design is finalized, the
drawings are brought into a CAD-CAM system that uses numerical data from the CADD drawing for actual
manufacturing.
There is separate category of programs called Computer Aided Engineering (CAE) that can use CADD drawing
for engineering analysis. The CAE programs have a number of applications in Structural Design, Civil Engineering,
Mechanical Engineering and Electrical Engineering. The Mechanical engineer can test a machine assembly and
also a prototype electronic model and test it without building a physical model.
We can do amazing things with CADD that we never thought possible while creating drawings with pen or pencil.
The following are some of the important capabilities that make CADD a powerful tool.
? Presentations
? Flexibility in editing
? Unit and accuracy levels
? Storage and access for drawings
? Sharing CADD drawings
Presentations
There are a number of ready-made presentations symbols available in CADD that can be used to enhance the look
of drawings. In addition to prepare impressive presentations on paper, we can use CADD to make an on-screen
presentations. Advanced CADD programs ever allow us to create an animated image.
Flexibility in editing
CADD allows us to work with great accuracy. If we need to create highly accuracy geometric shapes, CADD is the
answer. It can help avoid time-consuming mathematical calculations.
Unit and accuracy level
We can work with as high precession as 1/1000
th
of an inch.
Storage and access of drawing
A computer electronic filing system has the following advantages over the traditional filing system.
25 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
? It is quick and convenient to organize CADD drawing in a computer.
? It enables us to create a highly organized environment.
? An electronic drawing never gets old and faded.
Sharing CADD Drawing
The electronic drawing can be shared by a number of users, allowing them to Co-ordinate projects and work as a
team. This is accomplished by connecting different computer via a network.
About AutoCAD
AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design office in
the world. Although there are alternative CAD packages, AutoCAD is by far the most widely used system.
Autodesk's AutoCAD is the industry leader in CAD packages. Used by Civil Engineers, Architects, Mechanical and
Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and more
powerful features than its predecessor. The latest version of AutoCAD (at the time of writing) is AutoCAD 2011. Any
courses, whether through community colleges or online universities, that are related to Engineering or Architecture
should be considered incomplete if they do not introduce students to AutoCAD.
Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D 'models' can also be
created giving the designer absolute control over the design from start to finish. The computerized model can be
viewed through a 360? angle, and even 'rendered' with a texture on screen to give an idea of the finished product.
Co-ordinate system
AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This
point is (0,0). Every object is located in relation to the origin. If we were to draw a line straight out to the right from
26 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
the origin, this would be considered the positive X-axis. If we were to draw a line straight up, this would be the
positive Y-axis. The picture above shows a point located at (9, 6). This means that the point is 9 units over in the X-
axis and 6 units up in the Y-axis. When we are working with points, X always comes first. The other point shown is
(-10,-4). This means that the point is 10 units in the negative X-axis (left) and 4 units in the negative Y-axis (down).
A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the
screen. Most of the time we will not have an indication of where the origin is. We may need to draw a line from the
endpoint of an existing line. To do this we use relative points. These work the same way, but we have to add the @
symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. i.e.
1. ABSOLUTE POINTS are exact points on the drawing space.
2. RELATIVE POINTS are relative to an OBJECT on the drawing space
Angular Measurement
AutoCAD measures angles in a particular way also.
When drawing lines at an angle, we have to begin measuring the angle from 0 degrees, which is at the 3 o'clock
position. If we drew a line at 90 degrees, it would go straight up. The example shows a line drawn at +300 degrees
(270+30), or -60 degrees.
Entering Points in AutoCAD
We can enter points directly on the command line using three different systems. The one we use will depend on
which is more applicable for the situation. The three systems are as follows:
ABSOLUTE CO-ORDINATES - Using this method, we enter the points as they relate to the origin of the WCS. To
enter a point just enters in the exact point as X, Y.
27 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
RELATIVE CO-ORDINATES - This allows us to enter points in relation to the first point we have entered. After we've
entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point
to another point X units over and Y units up relative to the previous point.
POLAR CO-ORDINATES - We would use this system if we know that we want to draw a line a certain distance at a
particular angle. We would enter this as @D
The three ways of entering co-ordinates shown above are the ONLY way AutoCAD accepts input. First decide
which style we need to use, and then enter as shown. Remember that X is always before Y (alphabetical). Don't
forget the '@' symbol when we are entering relative points.
AutoCAD Basics
Application Button - This button displays commands for printing, saving, drawing utilities and other non-drawing tool.
Quick Access Toolbar - This is for quick access to common commands like New, Open, Save, Plot
Filename - The name of the current file we are working on.
Search Bar - Search for text in were drawing or search the help files.
Ribbon - The Ribbon has most of the commands/tools that we will use while we are working.
Tabs - A series of Tabs make up the Ribbon (Home, Insert, Manage, etc) and organize the Tools into common
groups.
Panels - Contain a group of tools
Tools - These are the icon that starts the commands we use to draw, modify, etc.
Tool Tip - If we however mouse over a tool, a tool tip will appear to give us more information. Hold it longer for
more info.
Drawing Space - These is where we draw were designs.
Command line - When we type a command, we will see it here. AutoCAD uses this space to 'prompt' us for
information. It will give us a lot of information and tell us where we are in the command.
Status bar - This allows seeing and changing different modes of drawing such as Ortho, Osnaps, Grid, Otrack, etc.
We can right click this area to toggle between icons and text for this area.
28 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
Basic Drawing Commands for Autocad
Measuring Commands
GRID (F7): Displays a grid of dots at a desired spacing on the screen.
Command: GRID (enter)
On/Off/Tick spacing(x)/Aspect: (enter value) (enter)
SNAP (F9): Specifies a "round off" interval so that points entered with the mouse can be locked into alignment with
the grid spacing.
Command: SNAP (enter)
On/Off/Value/Aspect/Rotate/Style: (enter value) (enter)
Basic Draw Commands
CIRCLE (C): Draws circles of any size.
Command: Circle (enter)
3P/2P/TTR/
Diameter or
LINE (L): Draws straight lines between two points
Command: LINE (enter)
From Point: (pick a point using the mouse) To Point: (Pick a point using the mouse)
To Point: (Press return to end the command)
ARC (A): Draws an arc (any part of a circle or curve) through three known points.
Command: ARC (enter)
Center/ < Start point > : (pick the first point on the arc)
Center/End/ < Second point >:C
Center: (pick the arc's center point)
Angle/Length of chord/
Display Commands
LIMITS: Sets the size of the drawing paper. For size "A" drawing paper the limits should be set for 10.5 x 8.
Command: LIMITS (enter)
On/Off/Lower left corner <0.0000> (enter)
Upper right corner: 10.5,8 (enter)
29 Format No.: FirstRanker/Stud/LM/34/Issue: 00/Revision: 00
ZOOM (Z): Enlarges or reduces the display of a drawing.
PAN: Allows we to move were view point around the drawing without changing the magnification factor.
Command: PAN (enter)
Editing Commands
CHANGE: Alters properties of selected objects
Command: CHANGE (enter)
Select objects or window or Last (select objects to be changed)
Properties/