Table Of ContentGlobal Consistency of Tolerances
The 61h CIRP International Seminar on Computer-Aided Tolerancing
The University ofTwente, Collegezalengebouw, Enschede, The Netherlands
March 22-24, 1999
Sponsored by
CIRP (International Institution for Production Engineering Research)
Stichting LPT (foundation Laboratory of Production and Design Engineering)
CIPV (Center for Integrated Manufacturing and Development)
University of Twente
International Program Committee
P. Bourdet (LURPA, ENS-Cachan, France)
A. Clement (Dassault Systemes, France)
H. Elmaraghy (University of Windsor, Canada)
L.E. Farmer (University of New South Wales, Australia)
C. Fortin (Ecole Polytechnique de Montreal, Canada)
I. Ham (Pennsylvania State University, USA)
F. Kimura (University of Tokyo, Japan)
V. Srinivasan (IBM, USA)
R. Weill (Technion, Israel)
National Organizing Committee
F.J.A.M. van Houten (Chairman)
H.J.J. Kals (Co-chair)
O.W. Salomons
D. Lutters
I. Dos Santos
Global Consistency of Tolerances
Proceedings of the 6th CIRP International Seminar on
Computer-Aided Tolerancing,
University of Twente, Enschede, The Netherlands,
22-24 March, 1999
Edited by
Fred van Houten
and
Hubert Kals
Department ofM echanical Engineering,
University ofTwente,
Enschede, The Netherlands
SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.
A C.I.P. Catalogue record for this book is available from the Library of Congress.
ISBN 978-90-481-5198-1 ISBN 978-94-017-1705-2 (eBook)
DOI 10.1007/978-94-017-1705-2
Printed an acid-free paper
AlI Rights Reserved
©1999 Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 1999
No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical,
including photocopying, recording or by any information storage and
retrieval system, without written permission from the copyright owner.
Contents
Keynote
Clement, A.; Riviere, A.; Serre, P.
Global consistency of Dimensioning and Tolerancing
Tolerance specification & allocation
Chen, M-S.; Young, K.M. 27
Optimising Tolerance Allocation for Mechanical Assemblies Considering
Geometric Tolerances Based on a Simplified Algorithm
Dantan, J-Y.; Ballu, A. 37
Functional and product specification by Gauge with Internal Mobilities
(G.I.M.)
Tsai, J-Ch.; Wang, W-W. 47
Development of a Computer-Aided Tolerancing System m CAD
Environment
Tolerances in manufacturing: general issues
Le Pivert, P.; Riviere, A. 55
Towards realistic simulation of machining processes
Farmer, L.E. 63
Estimating position tolerance process capabilities
Gaudet, P.; Cloutier, G.; Fortin, C. 73
The validation of a process plan by propagated dispersion zones
Tolerance representation & transfer
Desrochers, A.; Verheul, S. 83
A three dimensional tolerance transfer methodology
Britten, W.; Weber, C. 93
Transforming ISO 1101 Tolerances into Vectorial Tolerance Representations
-A CAD-Based Approach
Tolerances in clamping & fixturing
Krimmel, 0.; Martinsen, K. 101
Industrial application ofVectorial tolerancing to improve clamping of forged
workpieces in machining
vi
Carlson, J.S. 111
Root Cause Analysis for Fixtures and Locating Schemes Using Variation Data
Liu, J.; Yamazaki, K.; Kong, E. 121
On-Machine Quality Control System for TRUE-CNC Manufacturing System
Tolerance representation: from function to downstream processes
Ha, S.; Hwang, L; Lee, K.; Rho, H-M. 131
Tolerance Representation Scheme for Integrated Cutting Process &
Inspection Planning
Pairel, E.; Giordano, M.; Samper, S. 139
Towards easier and more functional semantics for geometrical tolerancing
Bley, H.; Olterman, R.; Thome, 0.; Weber, C. 149
A tolerance system to interface design and manufacturing
Tolerance representation: mathematical issues
Ballot, E.; Bourdet, P.; Thiebaut, F. 157
Contribution of a mathematical model of specifications of a part to their
coherence analysis
Linares, J.M.; Boukebbab, S.; Sprauel, J.M. 167
Parametric Tolerancing
Giordano, M.; Pairel, E.; Samper, S. 177
Mathematical representation of Tolerance Zones
Teaching of tolerancing
Lartigue, C.; Bourdet, P.; Timon, G. 187
On the education of the real geometry of mechanical parts through the
tolerancing and the tridimensional metrology
Ballu, A.; Mathieu, L. 197
Choice of functional specifications using graphs within the framework of
education
System for tolerance analysis
Alvarez, A.; Barbero, J.I.; Carrillo, A.R.; Gutierrez, T.; Aizpitarte, M. 207
TASys: A Computer aided Tolerance System based on a Variational
Geometry formulation
vii
Glancy, C. G.; Bogard, T.V. 215
Innovations in Integrating Tolerance Analysis Technologies for a
Computer-Aided Tolerancing System
Chang, M.; Kim, J.; Rho, H-M.; Ha, S. 223
Representation of assembly and inspection processes for the tolerance
analysis of automobile bodies
Industrial application I
Soderberg, R.; Lindkvist, L. 231
Two-Step Procedure for Robust Design Using CAT Technology
Schultheiss, R.; Hinze, U. 241
Detect the Unexpected- How to Find and Avoid Unexpected Tolerance
Problems in Mechanisms
Salomons, 0. W.; Begelinger, R.E.; Post E.; Houten F.J.A.M. van 251
Application of TTRS method in industrial practice; Tolerance specification
for industrial cooling water pumps
Tolerance analysis: kinematic & dynamic effects
Joskowicz, L.; Sacks, E. 261
The configuration space method for kinematic tolerance analysis
Salomons, 0. W.; Zwaag, J. van der; Zijlstra, J.; Houten, F.J.A.M. van 271
Dynamic Tolerance Analysis, part 1: A theoretical framework usmg
bondgraphs
Salomons, 0. W.; Zwaag, J. van der; Zijlstra, J.; Houten, F.J.A.M. van 283
Dynamic Tolerance Analysis, part II: Issues to be resolved when applying
bond graphs
Tolerance evaluation & computational metrology
Tanaka, F.; Kishinami, T. 293
Tolerance evaluation system of manufactured parts based on soft gaging
Limnararat, S.; Farmer, L.E. 303
An expert system for assessing flatness with a cmm
Gerth, R.J.; Klonaris, P.; Pfeiffer, T. 313
Cost Tolerance Sensitivity Analysis for Concurrent Engineering Design
Support
viii
Tolerance analysis: statistical approaches
Li, B.; Roy, U. 325
Motion constraints in a 2D polygonal assembly
Roy, U.; Li, B. 335
3D variational polyhedral assembly configuration
Sasaki, T.; Shinkai, M.; Higashiyama, K.; Tanaka, F.; Kishinami, T. 345
A Development of Statistical Tolerancing System for Optical Products
Industrial application II
Sellem, E.; de Hillerin, C.A.; Clement, A.; Riviere, A. 355
Modelling-Simulation-Testing of Compliant Assemblies
Marguet, B.; Mathieu, L. 365
Aircraft Assembly Analysis Method Taking Into Account Part Geometric
Variations
Global consistency and tolerance management
Wittmann, M.; Scheer, A.-W. 375
Integrated Tolerance Information System
Graves, S.B.; Bisgaard, S. 385
Integrated Tolerance Management
Srinivasan, V. 395
Role of Statistics in Achieving Global Consistency of Tolerances
Tolerance analysis: new approaches
Laperriere, L.; Lafond, P. 405
Tolerance Analysis And Synthesis Using Virtual Joints
Bennis, F.; Pino, L.; Fortin, C. 415
Analysis of positional tolerance based on the assembly virtual state
Teissandier, D.; Delos, V.; Couetard, Y. 425
Operations on polytopes: application to tolerance analysis
Author index 435
Keyword index 437
PREFACE
For a long time, tolerancing has been one of the most difficult and least understood
activities in design. Every designer knows that the proper functioning of a mechanical
device depends on the size of the clearances in the joints between the parts. However, it
appears to be rather problematic to assign clearances in complex assemblies in such a
way that all functional and assemblability requirements are guaranteed simultaneously.
Clearances, which essentially are attributes belonging to pairs of parts, have to be
converted into tolerances, which are attributes of single parts. This process has to be
carried out with manufacturability, exchangeability and maintainability considerations in
mind.
The relations between the tightness of tolerances and the manufacturing cost are usually
non-linear and do show discontinuities when the limits of process capabilities are
exceeded. Moreover, the relations between tightness of tolerances and the quality of
functioning are not always clear. Because of this, it is quite impossible for a human being
to define fully consistent interrelated sets of requirements for squareness, distance,
concentricity, straightness etc. Usually, tolerances are specified for every functional
requirement without much attention for the side effects. This leads easily to inconsistent
tolerancing schemes, which contain excessively tight tolerance values. As a result, the
parts become expensive and the proper functioning of the assembly is still not
guaranteed.
Global Consistency of Tolerances is becoming a hot topic, now computer-based
geometric modelling is getting mature. Presently it is possible to build virtual product
models with thousands of parts, which can have very complex shapes and geometric
relationships. However, the specification of allowable deviations from the nominal
geometry is still a big problem. Until now, the CADCAM systems used in industry have
provided inadequate support in the definition, analysis and synthesis of tolerances. Most
systems are even not capable of representing them properly.
Tolerancing has now become an important issue for CADCAM vendors. The latest
generation of CAD/CAM systems is using advanced geometric modelling and constraint
satisfaction kernels. The technology used in these kernels can be applied to macro
geometric aspects as well as micro geometric aspects.
The creation of virtual product models only for visualization and marketing purposes
does not pay off. The real profit can be made if the data can be used for the subsequent
downstream processes. For instance, the process planning function can be automated to a
high degree, if consistent micro geometry specifications are available.
A number of research groups is working on tolerancing issues for several years now.
They try to bridge the gap between the mathematical formulation of the problem and the
X
practical aspects in terms of computer representation, automatic or computer assisted
specification, consistency and completeness analysis and tolerance set optimization.
Some of these efforts have already resulted in commercially available tolerancing
software packages, which are being used in industry. Most of them are focussing on
tolerance analysis and optimization. Also efforts are being undertaken to bring the
tolerancing standards up to the present requirements.
Because the existing tolerance standards are still based on 2D drawing and conventional
machining, they do not hold any more in the world of 3D CAD, NC machining and
CMM. Moreover, with the ongoing miniaturization, the limited possibilities for
specifying shape tolerances starts to become a nuisance. Several ISO TC's and working
groups are proposing additions and alterations.
Different types of industries deal in different ways with tolerancing issues. In mass pro
duction, tolerancing is mainly based on statistical techniques, focussing on part
exchangeability versus manufacturing cost issues. In small batch manufacturing
tolerancing is usually based on worst case scenarios for assemblability. In both cases
however, there can also be an interest in functional degradation caused by wear and the
resulting increase or decrease of clearances with time. Kinematic and dynamic simulation
of the effect of changing clearances on the virtual product's behavior can be used to
predict malfunctions due to deterioration. In this way it becomes possible to establish
robust designs (a well functioning assembly, constituted of loosely tolerated parts).
Simulation can also support design decisions about aspects of wear, like tribological
conditions, material selection with respect to part re-use or recycling and maintainability
of the product.
Many companies do not have a clear methodology for tolerance specification. Most
designers use their intuition and experience. Sometimes they follow general guidelines.
As a consequence, most product designs do not contain all functionally relevant
tolerances while some tolerance values are too tight. A clear and reliable method for
tolerance specification is required as part of an overall tolerance management strategy.
Tolerance management includes all design, manufacturing and inspection activities,
striving to control and optimize the effect of geometrical variation. In this way Computer
Aided Tolerancing tools should be used to increase geometric robustness during concept
design and to assign tolerances on the basis of sensitivity, manufacturability and cost
during the detailing phase.
Within the context of robust design and life cycle engineering, education about consistent
tolerancing becomes a very important item. With a consistent tolerancing theory at hand
it becomes possible to teach robust design as a science.
The contents of this book originates from a collection of selected papers presented at the
6th CIRP International Seminar on Computer-Aided Tolerancing (CAT), organized by
CIPV (The Center for Integrated Manufacturing and Development) of the University of
Twente. The Seminar was sponsored by Stichting LPT (The foundation Laboratory of
