Advanced Fixture Design for FMS – With 105 Figures

Advanced Fixture Design for FMS
A.Y.C. Nee, K. Whybrew
and A. Senthil kumar
With 105 Figures
Advanced Manufacturing Series
Series Editor:D.T. Pham
Other titles in the series:
A Systems Approach to AMT Deployment
Eds. D.R. Towill and J. Cherrington
Human-Intelligence-Based Manufacturing
Ed. y.Ito
Intelligent Manufacturing: Programming Environments
for CIM
Eds. W.A. Gruver and J.e. Boudreaux
Automatic Supervision in Manufacturing
Ed. M. Szafarczyk
Modern Manufacturing: Information Control and
Technology
Eds. M. B. Zaremba and B. Prasad
Contents
Chapter 1 Fixtures and flexible manufacturing systems ••• 1
1.1 Introduction . 1
1.2 AMT and fixtures 2
1.2.1 Fixture design and rate of return on
investment . 2
1.2.2 Fixture design and production leadtime . 7
1.3 Fixture strategies for FMS . 7
1.4 References . 9
Chapter 2 Fixture design fundamentals . 11
2.1 Introduction . 11
2.2 Definitions . 12
2.3 Fixture design . . . . . 16
2.4 Design outcomes . 17
2.4.1 Fixture plan 19
2.4.2 Fixture layout 22
2.4.3 Fixture element design 25
2.4.4 Fixture body design 26
2.5 Design criteria . . 27
2.5.1 Design specification 27
2.5.2 Factory standards . 27
2.5.3 Ease of use . 27
2.5.4 Cost . 28
2.6 Design techniques . 28
2.6.1 Axiomatic design 28
2.6.2 Rule-based design 40
2.6.3 Group technology . 41
2.6.4 Parametric retrieval 42
2.6.5 Algorithms and analysis tools 42
2.6.6 Design procedure . 44
2.7 Conclusions 47
2.8 References . 47x Contents
Chapter 3 Tolerance control and location surfaces . 49
3.1 Manufacturing tolerance stacks 49
3.2 Tolerance charts 55
3.3 A new tolerance charting algorithm . 60
3.4 CAPPFD . 69
3.5 Conclusions 73
3.6 References . 73
Chapter 4 Flexible fixture systems . . 75
4.1 Introduction . 75
4.2 Evaluation of fixture systems . 76
4.2.1 Capital cost . 76
4.2.2 Recurring cost . 77
4.2.3 Fitness for purpose . 78
4.2.4 Short-term flexibility . 83
4.2.5 Long-term flexibility . 85
4.3 Flexible fixturing . 85
4.3.1 Modular fixtures . 85
4.3.1.1 Baseplate, riser blocks and tooling blocks 91
4.3.1.2 Locators, supports and clamps 93
4.3.1.3 Tooling cubes, modular blocks and shims 98
4.3.1.4 Evaluation of modular fixture systems 102
4.3.2 Flexible pallet systems . 105
4.3.3 Phase-change fixtures 106
4.3.3.1 Authentic phase-change fixtures 108
4.3.3.2 Pseudo phase-change fixtures 109
4.3.4 Conformable fixtures . 113
4.3.5 Programmable fixtures . 116
4.4 Conclusions 117
4.5 References . 119
Chapter 5 Computer-aided fixture design .• 122
5.1 Computer-aided design of fixtures . 122
5.2 Approaches in fixture design 122
5.2.1 Variant fixture design 122
5.2.2 Generative fixture design . 124
5.3 Fixture design techniques 125
5.3.1 CAD tools for fixture design . 125
5.3.2 Group technology concept for fixture
design 125
5.3.3 AI and expert systems in fixture design . 126
5.3.4 Optimization of fixture configurations . 126
5.4 Fixture design systems 127
5.4.1 Interactive fixture design systems . 127Contents xi
5.4.2 Semi-automated fixture design systems 127
5.4.3 Automated fixture design systems 128
5.5 A variant fixture design system using GT 128
5.5.1 A feature-based classification and coding
scheme . 130
5.5.2 Case indexing 133
5.5.3 Case retrieval 135
5.5.4 Case modification . 137
5.6 A generative fixture design system using an expert
system . 138
5.6.1 Workpiece design module 138
5.6.2 Fixture design module . 140
5.6.3 Case studies 147
5.6.4 System implementation 148
5.7 References . 151
Chapter 6 Analysis methods for workpiece distortion
and deflection 155
6.1 Introduction . 155
6.2 Clamping devices 156
6.2.1 Basic requirements . 156
6.2.2 The magnitude and distribution of
clamping forces 156
6.2.3 Types of clamping devices, clamping action
and theoretical estimation of clamping forces 157
6.2.3.1 Screw clamps . 157
6.2.3.2 Strap clamps 159
6.2.3.3 Toggle clamps 160
6.2.3.4 Power clamps 161
6.3 Machining forces, force models for milling and
drilling . 161
6.3.1 Milling force models . 161
6.3.2 Drilling force models . 162
6.4 Theoretical formulation of workpiece deformation
using analytical methods . 162
6.4.1 Modelling of workpiece deformation 163
6.4.2 Parameters considered in simulating
workpiece deformation 164
6.4.3 Simulation results . 168
6.4.3.1 Using parameters as shown in Table 1 168
6.4.3.2 Using parameters as shown in Table 2 169
6.5 Conclusions 169
6.6 References . 173xii Contents
Chapter 7 Future trends and developments in fixturing
methodologies 175
7.1 Introduction . 175
7.2 An industrial perspective on fixture design 175
7.3 Future design methodologies . 177
7.3.1 Concurrent engineering and fixture design . 178
7.3.2 Generic fixture design . 179
7.3.3 Case-based learning 180
7.4 Fixturing techniques . 180
7.4.1 Modular fixtures . 181
7.4.2 Phase-change fixtures 182
7.4.3 Vision systems . 182
7.4.4 Dynamic fixtures to meet uncertainties
and changes in scheduling 182
7.5 References . 183
Bibliography 184
Index .
Index
Advanced manufacturing 1
Analysis
cutting 43
economic 42
FEM 168
stress 43
tolerance 44
workpiece control 42
Automated systems
expert systems 126
knowledge 126
robots 126
Axiomatic design 28
Build-up error 84
Balance dimension 51
Baseplates 91
CAPPFD 69
Case
indexing 133
modification 137
retrieval 135
Cerrobend 108
CIM 7
C~ps 13,93,157
power 161
screw 157
strap 159
toggle 160
Clamping
basic requirements 156
magnitude 156
Clamping force
Coding
distribution 156
estimation 157
fixture element 132
workpiece 132
Coding and classification 130
Component
orientation 20
Conformable clamps 114
Cost
amortization n
capital 76
commissioning 76
design 76
fabrication 76
recurring n
Coulomb’s friction 163
Dedicated fixtures 75
Design cost 76
Design criteria 27
Design systems202 Advanced Fixture Design for FMS
automated 128
interactive 127
semi-automated 127
Design techniques 28
axiomatic design 28
Dimension
balance 51
blueprint 51
final 53
working 51
Dimensional control 33
Elastic robot gripper 109
Element selection 145
Evaluating fixturability 178
Face configuration 144
Feature extraction 140
Final dimension 53
Fitness 78
Fixture
classification 130, 132
conformable 113
dynamics 182
non-conformable 137
layout 22
plan 19
Fixture body 16,81
Fixture body design 26
Fixture design
AI 126
case-based 180
concurrent 178
generic 179
CAD 138
design outcomes
16,17
generative 124,138,179
group technology 125
MEFDES 138
methodologies 1n
optimization 126
techniques 125, 180
trends 175
variant 128
FIXture element design 25
FIXture strategies for FMS 7
FJXturing sequence 22
Flexible fixtures
modular fOOures 85
pallet 105
programmable 116
Flexible fixturing 75
phase-change 106
Flexibility
mix 2
route 2
short term 3,83
volume 2
Fluidized bed 111
FMS
cell based 3
monolithic 5
types 3
Force Models
drilling 162
milling 161
Future trends 175
Geometric control 29
Group technology 41
Hole-based system
Bliico Technik 90
Imao 90
Kipp 90SAFE 90
Venlic 90
conftgUl’ability 90
Investment
rate of return 2
lust-in-time 6
Knowledge acquisition 178
Knowledge representation
face 138
feature 142
modular element 145
point 145
set-up 144
Locator 12,93
Long-term flexibility 85
Machining features 141
Manufacturing tolerance 49
ME30 148
Mechanical control 35
Modular elements
locating 93,96
supporting 93,96
riser/tooling 91
baseplates 91
clamping elements 93
tooling cubes 91,99
Modular fIXtures 85
advantages of 89
applications of 87
classification of 90
evaluation 102
Multi-leaf vice 114
NEXPERT Object 132
Parametric retrieval
elements 42
Petal collet 115
Index 203
Phase-change fixturing 106,182
authentic 108
pseudo 109
Point determination 144
Programmable fIXtures 116
Rule-based design 40, 128
Rule induction 180
Set-up n,142,144
face abnormal 143
machining dir 142
tolerance factor 143
Slot-based system 90
CATIC 90
Halder 90
Warton Unitool 90
Storage cost 78
Support 13,93
Surface
clamping 21
location 21
support 21
Tolerance charts 55
nominal dimension 65
preparation 61
rooted-tree 62
stock removal 64
Tolerance charting
algorithm 60
Tolerance stacks
manufacturing 49
Tool collision 81
Tool interference 81
Trends204 Advanced Fixture Design for FMS
modular fIXtures 181
phase-change 182
vision 182
Variant 122
Working dimension 51
calculation 65
Workpiece control 29
Workpiece deformation
formulation 162
fIXture interaction 162
modelling 163
parameters 164
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