Design of Jigs, Fixtures and Press Tools

Abstract

This book is suitable to the engineering students of B.E. for those wish to gain a sound knowledge and understanding of the principles of Design of Jigs, Fixtures, and Press Tools. This book is designed to meet with the requirement of revised syllabus prescribed by the Anna University, Chennai, Trichy & Coimbatore & Tirunelveli effective from June 2013 for 7th Semester Mechanical Engineering students of its affiliated colleges.
This book consists of 5 units.
Unit 1 deals with objectives of tool design, functions, types, elements and advantages of jigs and fixtures, principles of location and clamping, locating methods and devices, drill bushes and jig buttons, tolerances and materials used.
Unit 2 is concerned with different types of jigs such as post, turnover, channel, latch, box, pot, indexing, angular post jigs, and general principles of milling, lathe, boring, broaching, and grinding, assembly, inspection and welding fixtures. Also, it deals with design and development of jigs and fixtures for given components.
Unit 3 has an in depth dealing of various topics such as press working terminologies, types of presses, computation of press capacity, strip layout calculations, press work materials, center of pressure calculations, design of various elements of dies, design of simple blanking, piercing, compound and progressive dies.
The concept of blank development for bending, forming, and drawing operations, elements of different dies, design and development of bending, forming, drawing and combination dies are elaborately discussed in Unit 4.
Unit 5 illustrates various operations such as bulging, swaging, embossing, coining, curling, hole flanging, shaving and sizing. Recent trends in tool design and Poka Yoke concepts are also introduced in the later part of this unit.

Full text

Design of Jigs, Fixtures & Press Tools
For 7th Semester B.E. Mechanical Engineering (Elective) and
B.E. Automobile Engineering (Elective)
As per the Latest Syllabus of ANNA UNIVERSITY, CHENNAI
Dr. G.K. VIJAYARAGHAVAN, B.E., M.Tech., Ph.D.
Adviser,
Dhaanish Ahmed College of Engineering,
Padappai, Chennai, Tamilnadu.
E-mail: haigkv@yahoo.com
Website: wwww. gkvbooks.comm
Dr. S.SUNDARAVALLI, M.Tech., Ph.D.
Visiting Faculty,
Manipal University, Dubai.
Dr. A. MURUGANANDAM, B.E., M.Tech., Ph.D.
Former Professor,
Department of Mechanical Engineering,
PSNA College of Engineering & Technology,
Dindigul, Tamilnadu.
Suchitra Publications
Plot No.73, Gokula Nagar, 2nd Main Road (40 Feet Road),
Perumbakkam, Medavakkam (P.O),
Chennai – 600 100, Tamil Nadu, INDIA.
Phone: 044 - 49523977, 98945 98598, 96772 21371.
E-mail: lakshmipublications@gmail.com, suchitrapublications@gmail.com

Design of Jigs, Fixtures & Press Tools
By Dr. G.K. Vijayaraghavan, Dr. S. Sundaravalli & Dr. A. Muruganandam
First Edition: July 2011
Fully Revised Seventh Edition: May 2016
© All rights are exclusively reserved by the authors
No part of this publication can be reproduced, stored in a retrieval system or transmitted in any
form or by any means, mechanical, photocopying, recording or otherwise, without the prior
written permission of the author.
Price: Rs. 280/-
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SUCHITRA PUBLICATIONS
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Perumbakkam, Medavakkam P.O,
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Phone: 044 - 49523977
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PREFACE
We are pleased to bring out our fully revised seventh edition of “Design of Jigs,
Fixtures & Press Tools” book for Engineering and Technology studies. This book is
written to serve the needs of under graduate students embarking introductory course in
Design of Jigs, Fixtures & Press Tools. This book is based on the latest syllabi
prescribed by the Anna University Chennai, Trichy, Coimbatore & Tirunelveli for 7h
Semester Mechanical engineering and Automobile engineering students of its
affiliated colleges.
This book consists of 5 units.
 Unit 1 deals with objectives of tool design, functions, types, elements and
advantages of jigs and fixtures, principles of location and clamping, locating
methods and devices, drill bushes and jig buttons, tolerances and materials used.
 Unit 2 is concerned with different types of jigs such as post, turnover, channel,
latch, box, pot, indexing, angular post jigs, and general principles of milling, lathe,
boring, broaching, and grinding, assembly, inspection and welding fixtures. Also, it
deals with design and development of jigs and fixtures for given components.
 Unit 3 has an in depth dealing of various topics such as press working
terminologies, types of presses, computation of press capacity, strip layout
calculations, press work materials, center of pressure calculations, design of various
elements of dies, design of simple blanking, piercing, compound and progressive
dies.
 The concept of blank development for bending, forming, and drawing operations,
elements of different dies, design and development of bending, forming, drawing
and combination dies are elaborately discussed in Unit 4.
 Unit 5 illustrates various operations such as bulging, swaging, embossing, coining,
curling, hole flanging, shaving and sizing. Recent trends in tool design and Poka
Yoke concepts are also introduced in the later part of this unit.
Important solved problems and past examination Anna University question
paper’s solved problems have been added in each unit which will enable the students

to score high marks in the University examinations. In addition to this, two mark
questions and answers are added at the tail end of each unit.
With these features, we sincerely hope that this book would serve as a valuable
text for the students.
Though efforts have been taken aiming at a ‘zero flaw’ content, we do recognize
that mistakes may have inadvertently crept in. We welcome constructive criticisms on
any specific topics of this book.
Our sincere thanks to Mrs. Nirmala Durai, Proprietor of “Lakshmi
Publications” and Publishing Advisor Mr. A. DURAI, B.E. for their involvement to
make this publication successful.
- Authors

ME6006 DESIGN OF JIGS, FIXTURES AND PRESS TOOLS
UNIT I LOCATING AND CLAMPING PRINCIPLES
Objectives of tool design- Function and advantages of Jigs and fixtures – Basic elements
– principles of location – Locating methods and devices – Redundant Location –
Principles of clamping – Mechanical actuation – pneumatic and hydraulic actuation
Standard parts – Drill bushes and Jig buttons – Tolerances and materials used.
UNIT II JIGS AND FIXTURES
Design and development of jigs and fixtures for given component- Types of Jigs – Post,
Turnover, Channel, latch, box, pot, angular post jigs – Indexing jigs – General principles
of milling, Lathe, boring, broaching and grinding fixtures – Assembly, Inspection and
Welding fixtures – Modular fixturing systems- Quick change fixtures.
UNIT III PRESS WORKING TERMINOLOGIES AND ELEMENTS OF CUTTING DIES
Press Working Terminologies - operations – Types of presses – press accessories –
Computation of press capacity – Strip layout – Material Utilization – Shearing action –
Clearances – Press Work Materials – Center of pressure- Design of various elements of
dies – Die Block – Punch holder, Die set, guide plates – Stops – Strippers – Pilots –
Selection of Standard parts – Design and preparation of four standard views of simple
blanking, piercing, compound and progressive dies.
UNIT IV BENDING AND DRAWING DIES
Difference between bending and drawing – Blank development for above operations –
Types of Bending dies – Press capacity – Spring back – knockouts – direct and indirect –
pressure pads – Ejectors – Variables affecting Metal flow in drawing operations – draw
die inserts – draw beadsironing – Design and development of bending, forming, drawing,
reverse redrawing and combination dies – Blank development for axisymmetric,
rectangular and elliptic parts – Single and double action dies.
UNIT V OTHER FORMING TECHNIQUES
Bulging, Swaging, Embossing, coining, curling, hole flanging, shaving and sizing,
assembly, fine Blanking dies – recent trends in tool design- computer Aids for sheet metal
forming Analysis – basic introduction - tooling for numerically controlled machines- setup
reduction for work holding – Single minute exchange of dies – Poka Yoke.

CONTENTS
UNIT 1 LOCATING AND CLAMPING PRINCIPLES
UNIT 2 JIGS AND FIXTURES
UNIT 3 PRESS WORKING TERMINOLOGIES AND
ELEMENTS OF CUTTING DIES
UNIT 4 BENDING AND DRAWING DIES
UNIT 5 OTHER FORMING TECHNIQUES
DESIGN OF JIGS, FIXTURES AND PRESS
TOOLS

Contents C-1
1.1. Objectives of tool design 1.1
1.2. Introduction to jigs and fixtures 1.2
1.3. Functions of jigs 1.3
1.4. Functions of fixtures 1.3
1.5. Advantages of jigs and fixtures 1.4
1.6. Basic elements of jigs and fixtures 1.4
1.7. Principles of jigs and fixtures design 1.5
1.8. Essential features of jigs or fixtures 1.7
1.9. Difference between jigs and fixtures 1.9
1.10. Principles of location 1.9
1.10.1. Degree of freedom 1.10
1.10.2. Six point location principle or
3-2-1 principle of location 1.10
1.10.3. Principle of least points 1.12
1.10.4. Principle of extreme positions 1.12
1.10.5. Principle of mutually perpendicular planes 1.13
1.10.6. Principle of fool-proofing 1.14
1.11. Locating methods and devices 1.15
1.11.1. Pin and button locators 1.15
1.11.2. V – locators 1.20
1.11.3. Bush locators 1.22
1.11.4. Nest or cavity locators 1.23
1.12. Redundant location 1.24
1.13. Principles of clamping 1.25
1.14. Clamping devices 1.27
1.15. Mechanical actuation clamps 1.27
1.15.1. Screw clamp 1.27
UNIT 1 LOCATING AND CLAMPING PRINCIPLES

C-2 Design of Jigs, Fixtures and Press Tools
1.15.2. Strap clamp or lever clamp 1.28
1.15.3. Latch clamp 1.33
1.15.4. Hinged clamp or pivoted clamp 1.36
1.15.5. C-clamp 1.37
1.15.6. Cam operated clamp 1.38
1.15.7. Wedge clamp 1.40
1.15.8. Quick acting nut 1.40
1.15.9. Toggle clamp 1.41
1.15.10. Bayonet clamp 1.42
1.15.11. Hook Bolt clamp 1.43
1.15.12. Equalising clamp 1.44
1.16. Pneumatic and hydraulic actuation clamps 1.44
1.17. Magnetic clamps 1.46
1.18. Non-conventional clamping 1.47
1.18.1. Adhesive clamping 1.47
1.18.2. Fusion clamping 1.47
1.19. Standard parts of jigs and fixtures 1.47
1.19.1. Bases 1.48
1.19.2. Rest buttons 1.48
1.19.3. Pins 1.49
1.19.4. Handles and hand knobs 1.50
1.19.5. Feet 1.51
1.19.6. Lift rings 1.51
1.19.7. Clamps strap and cams 1.52
1.19.8. Threaded fasteners and associated parts 1.52
1.19.9. Stock sections 1.53
1.19.10. Drill bushes 1.54
1.20. Jig button or jig feet 1.59
1.21. Tolerance 1.59
1.21.1. Tolerance analysis 1.59

Contents C-3
1.21.2. Solved problems 1.62
1.22. Materials used in jigs and fixtures 1.64
1.23. Two mark questions and answers 1.66
1.24. Solved questions and answers 1.77
2.1. Jig 2.1
2.2. Elements of a jig 2.1
2.3. Types of jigs 2.3
2.3.1. Boring jig 2.4
2.3.2. Drill jig 2.4
2.3.3. Template jig 2.5
2.3.4. Plate jig 2.6
2.3.5. Latch or leaf jig 2.7
2.3.6. Sandwich jig 2.7
2.3.7. Channel jig 2.8
2.3.8. Box jig 2.9
2.3.9. Post jigs or angle plate jig 2.10
2.3.10. Angular post jig 2.11
2.3.11. Turnover jigs or table type jig 2.13
2.3.12. Pot jig 2.13
2.3.13. Solid jig 2.14
2.3.14. Trunnion jig 2.15
2.3.15. Indexing jig 2.16
2.3.16. Universal jig 2.17
2.3.17. Pump jig 2.17
2.3.18. Multi-station jig 2.18
UNIT 2 JIGS AND FIXTURES

C-4 Design of Jigs, Fixtures and Press Tools
2.4. Automatic drill jig 2.18
2.4.1. Rack and pinion operated drill jig 2.19
2.4.2. Air-operated or pneumatic jig 2.20
2.4.3. Hydraulic operated jig 2.22
2.4.4. Pneumo-hydraulic jig 2.22
2.5. Design and development of jig for given components 2.23
2.6. Fixtures 2.35
2.7. Types of fixtures 2.36
2.7.1. Plate fixture 2.36
2.7.2. Angle plate fixture 2.37
2.7.3. Vice-jaw fixture 2.39
2.7.4. Multi-station fixture 2.40
2.7.5. Profiling fixture 2.40
2.8. Lathe fixtures or turning fixture 2.41
2.8.1. Faceplate turning fixture 2.42
2.8.2. Built up turning fixture 2.43
2.9. Milling fixture 2.44
2.9.1. Special vice jaw 2.46
2.9.2. Simple or plain milling fixture 2.48
2.9.3. Straddle milling fixture 2.49
2.9.4. String or line milling fixture 2.50
2.9.5. Gang milling fixture 2.51
2.9.6. Indexing milling fixture 2.53
2.9.7. Key-way milling fixture 2.54
2.9.8. Contour and profile milling fixture 2.54
2.9.9. Adjustable and movable milling fixture 2.54
2.10. Boring fixture 2.55
2.11. Broaching fixture 2.58
2.11.1. Key-way broaching fixture 2.58
2.11.2. External surface broaching fixture 2.60

Contents C-5
2.12. Grinding fixture 2.60
2.12.1. Cylindrical grinding fixture 2.61
2.12.2. Surface grinding fixture 2.63
2.12.3. Angle plate grinding fixture 2.66
2.13. Planing fixture 2.66
2.14. Shaping fixture 2.69
2.14.1. Internal keyway cutting fixture 2.69
2.14.2. Slot fixture 2.69
2.15. Assembly fixtures 2.71
2.15.1. Universal fixture 2.71
2.15.2. Special purpose fixture 2.72
2.16. Inspection fixture 2.73
2.16.1. Components of inspection fixture 2.74
2.17. Welding fixture 2.76
2.17.1. Tack welding fixture 2.78
2.17.2. Wing nut welding fixture 2.78
2.17.3. Butt welding fixture 2.79
2.17.4. Angle frame welding fixture 2.80
2.18. Cast fixture 2.81
2.19. Solid fixture 2.83
2.20. Gear hobbing fixture 2.83
2.21. Plastic fixture 2.84
2.22. Pneumatic fixture 2.85
2.23. Hydraulic fixture 2.86
2.24. Modular fixturing systems 2.86
2.24.1. Types of modular fixturing systems 2.86
2.24.2. Standard modular fixturing elements 2.92
2.25. Quick change fixture 2.99
2.26. Design and development of fixture for given components 2.101

C-6 Design of Jigs, Fixtures and Press Tools
2.27. Solved Anna University problems 2.106
2.28. Two mark questions and answers 2.143
2.29. Solved questions and answers 2.156
3.1. Press working 3.1
3.2. Press working terminology 3.2
3.3. Working principle of a die set 3.4
3.4. Press working operations 3.5
3.5. Types of presses 3.8
3.5.1. Fly press 3.10
3.5.2. Mechanically operated power press or OBI press 3.11
3.5.3. Inclined press 3.12
3.5.4. Inclinable press 3.12
3.5.5. Gap press 3.13
3.5.6. Arch press 3.13
3.5.7. Straight side press 3.13
3.5.8. Horn press 3.14
3.5.9. Crank driven press 3.14
3.5.10. Eccentric driven press 3.14
3.5.11. Rack and gear driven presses 3.14
3.5.12. Hydraulically driven presses 3.14
3.5.13. Presses with knuckle joint drive 3.14
3.5.14. Presses with toggle drive 3.15
3.5.15. Presses with screw drive 3.15
3.5.16. Single-action presses 3.15
UNIT 3 PRESS WORKING TERMINOLOGIES AND
ELEMENTS OF CUTTING DIES

Contents C-7
3.5.17. Double-action presses 3.16
3.5.18. Triple-action presses 3.16
3.6. Press accessories 3.16
3.6.1. Strip feed system 3.16
3.6.2. Gripper rail system 3.17
3.6.3. Feed device to convey single workpiece in steps 3.18
3.6.4. Edge cutter 3.18
3.6.5. Spring actuated strip guide 3.19
3.7. Computation of press capacities and tonnage requirements 3.20
3.7.1. Press capacity for cutting operations 3.20
3.7.2. Tonnage limited by flywheel capacity 3.20
3.7.3. Tonnage limited by the motor 3.21
3.8. Selection of press 3.21
3.9. Strip layout 3.22
3.9.1. Solved problem on strip layout 3.23
3.10. Material utilization 3.25
3.11. Shearing action 3.27
3.12. Clearance 3.28
3.12.1. Blanking 3.28
3.12.2. Piercing 3.29
3.13. Press work materials 3.30
3.13.1. Tempers of press work materials 3.30
3.14. Centre of pressure 3.31
3.14.1. Solved problems on centre of pressure 3.32
3.15. Dies 3.34
3.16. Types of dies 3.34
3.16.1. Simple dies 3.34
3.16.2. Progressive dies 3.35
3.16.3. Compound dies 3.36
3.16.4. Combination dies 3.38

C-8 Design of Jigs, Fixtures and Press Tools
3.17. Design of various elements of progressive, combination and
compound dies 3.40
3.17.1. Die set 3.40
3.17.2. Die block 3.42
3.17.3. Bolster plate 3.44
3.17.4. Punch plate and backup plate 3.44
3.17.5. Punch 3.46
3.17.6. Smallest hole that can be punched 3.50
3.17.7. Solved problems on punching 3.51
3.17.8. Punch holder 3.51
3.17.9. Guide plate or stock guide 3.52
3.17.10. Guide pins and bushes 3.53
3.17.11. Strippers 3.55
3.17.12. Knockouts 3.61
3.17.13. Stock stops 3.61
3.17.14. Pilots 3.64
3.18. Selection of standard parts 3.68
3.19. Design of simple blanking, piercing, compound and
progressive dies 3.69
3.19.1. Design and development of blanking and piercing dies 3.70
3.19.2. Solved problems on die design 3.74
3.20. Solved Anna University problems 3.87
3.21. Two mark questions and answers 3.101
3.22. Solved questions and answers 3.114
4.1. Introduction to bending, forming and drawing dies 4.1
4.2. Difference between bending, forming and drawing 4.1
4.3. Bending dies 4.2
UNIT 4 BENDING AND DRAWING DIES

Contents C-9
4.3.1. Types of bending dies 4.2
4.3.2. Bending force 4.3
4.3.3. Bend allowance 4.4
4.3.4. Springback 4.6
4.4. Forming dies 4.6
4.5. Types of forming dies 4.6
4.5.1. Solid form dies 4.6
4.5.2. Pad-type form dies 4.7
4.5.3. Embossing dies 4.8
4.5.4. Coining dies 4.8
4.5.5. Bulging dies 4.8
4.6. Drawing dies 4.9
4.6.1. Types of drawing dies 4.10
4.6.2. Factors affecting drawing 4.11
4.7. Blank holding pressure 4.11
4.8. Redrawing 4.11
4.9. Direct redrawing 4.12
4.10. Indirect redrawing or reverse redrawing 4.12
4.11. Ironing 4.13
4.12. Blank development for drawing operation 4.14
4.13. Blank development for combined bending and drawing operation 4.14
4.14. Press capacity 4.15
4.14.1. Press capacity for drawing operations 4.15
4.14.2. Press capacity for bending operations 4.16
4.14.3. Tonnage ratings 4.17
4.15. Knockouts 4.18
4.16. Pilots 4.18
4.17. Pressure pads 4.18
4.18. Ejectors 4.19
4.18.1. Types of ejector pins 4.20

C-10 Design of Jigs, Fixtures and Press Tools
4.19. Variables affecting metal flow in drawing operation 4.21
4.19.1. Radius on punch 4.21
4.19.2. Radius on die 4.21
4.19.3. Friction 4.21
4.19.4. Material to be drawn 4.22
4.19.5. Drawing speed 4.22
4.19.6. Die clearance 4.22
4.20. Draw die inserts 4.22
4.21. Draw beads 4.23
4.22. Design and development of bending, forming, drawing reverse
re-drawing and combination dies 4.24
4.22.1. Design and development of bending dies 4.24
4.22.2. Design of forming dies 4.28
4.22.3. Design of drawing dies 4.29
4.23. Single action dies 4.32
4.24. Double action dies 4.33
4.25. Solved problems 4.35
4.26. Solved Anna University problems 4.46
4.27. Two mark questions and answers 4.52
4.28. Solved questions and answers 4.59
5.1. Bulging 5.1
5.2. Swaging 5.3
5.3. Embossing 5.5
5.4. Coining 5.7
5.5. Curling 5.8
5.6. Hole flanging 5.9
UNIT 5 OTHER FORMING TECHNIQUES

Contents C-11
5.7. Shaving and sizing 5.10
5.8. Assembly 5.11
5.8.1. Riveting 5.11
5.8.2. Crimping 5.12
5.8.3. Seaming 5.14
5.9. Fine blanking die 5.15
5.10. Recent trends in tool design 5.16
5.11. Computer aids for sheet metal forming analysis 5.16
5.12. Tooling for numerically controlled machines 5.18
5.12.1. Functions of the numerical controller 5.18
5.12.2. Limitations of conventional NC machine tools 5.19
5.12.3. Machining centers 5.19
5.12.4. Advantages of machining centers 5.19
5.12.5. Design difficulties of NC machine tool fixtures 5.19
5.12.6. Need of fixtures for NC machine tool 5.20
5.13. Fixtures for NC machine tools 5.20
5.14. Strap clamp or heel block 5.20
5.15. Standard vises and chucks 5.20
5.15.1. Types of vises 5.20
5.15.2. Chucks 5.22
5.16. Modular fixtures 5.23
5.17. Setup reduction for work holding 5.24
5.18. Setup reduction procedure 5.24
5.18.1. Setup reduction during designing of workpiece 5.24
5.18.2. Setup reduction during processing of workpiece 5.26
5.18.3. Setup reduction during designing of workholder 5.27
5.19. Single Minute Exchange of Dies (SMED) 5.28
5.19.1. Four steps to SMED 5.29
5.19.2. Advantages of SMED 5.30
5.20. POKA YOKE 5.30

C-12 Design of Jigs, Fixtures and Press Tools
5.20.1. Examples of POKAYOKE 5.31
5.20.2. Types of POKAYOKE 5.31
5.20.3. Control POKA YOKE 5.31
5.20.4. Warning POKA YOKE 5.32
5.20.5. Advantages of Poke Yoke 5.33
5.21. Two mark questions and answers 5.34
5.22. Solved questions and answers 5.42
Model questions paper MQ-1
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