Investigating Accumulation of Tolerances and Its Impact on the Reliability of Job Site Installation

176 Pages·2007·5.33 MB·English

by  Tapas Acharjee

UNIVERSITY OF CINCINNATI

Date:___________________

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hereby submit this work as part of the requirements for the degree of:

in:

:
It is entitled

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Chair: _______________________________

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Investigating Accumulation of Tolerances and
Its Impact on Reliability of Job Site Installation

A Thesis Submitted to the
Graduate School
of the University of Cincinnati

In partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE

In the Department of Civil & Environmental Engineering
of the College of Engineering

Winter 2007

By

TAPAS ACHARJEE

A.M.I.E (Civil) - Bachelor of Engineering
Institution of Engineers (India), Summer 1999

Committee Chair

Cynthia C.Y. Tsao, Ph.D.
ABSTRACT
Investigating the Accumulation of Tolerances and
Its Impact on Reliability of Job Site Installation
by
Tapas Acharjee
Master of Science-Department of Civil and Environmental Engineering
University of Cincinnati

Cynthia C.Y. Tsao, Ph.D. - Chair

Architecture-Engineering-Construction projects may account for product and process design
tolerances within drawings and specifications. However, as projects combine a series of
components, these tolerances will accumulate. Failure to manage this accumulation can result
in component misfits or poor quality of installed work, revealing a lack of product and
process design integration.
This thesis investigates how tolerance accumulation contributed to breakdowns in
bleacher installation on a tennis court project. Building upon earlier work, we create product
tolerance, process sequence maps, and generate a tolerance accumulation matrix for a
bleacher module to identify components that have the greatest impact on job-site assembly.
We discuss how to prevent breakdowns on future projects by restructuring work to enable
predictable workflow and achieve better built-in quality. In particular, we explore how to
introduce poka-yoke devices as well as changes in contracting, work sequencing, modularity,
and new product development to achieve efficient delivery of bleacher systems.

TABLE OF CONTENTS
1 INTRODUCTION...........................................................................................................1
1.1 TOLERANCES.........................................................................................................1
1.2 PROBLEM STATEMENT.......................................................................................2
1.3 CURRENT TOLERANCE RESEARCH IN AEC...................................................4
1.4 RESEARCH HYPOTHESES...................................................................................7
1.5 RESEARCH SCOPE.................................................................................................8
1.6 RESEARCH DESCRIPTION...................................................................................9
1.7 RESEARCH METHODOLOGY............................................................................10
1.8 CASE STUDY SELECTION..................................................................................11
1.9 TOLERANCE TERMINOLOGY EXPLAINED...................................................11
2 FUNDAMENTALS OF MANUFACTURING TOLERANCE................................14
2.1 VARIATION AND TOLERANCE........................................................................14
2.2 HISTORY................................................................................................................15
2.3 CATEGORIES OF TOLERANCES.......................................................................18
2.3.1 (GD&T) Size Tolerance..................................................................................19
2.3.2 (GD&T) Form and Profile Tolerance.............................................................21
2.3.3 (GD&T)- Orientation Tolerance.....................................................................22
2.3.4 (GD&T)- Location Tolerance.........................................................................23
2.4 (GD&T)-TOLERANCE ZONES AND ENVELOPES..........................................24
2.5 TOLERANCE RATIONALE.................................................................................28
2.6 ELEMENTS OF TOLERANCING........................................................................30
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2.6.1 Datum and datum feature................................................................................30
2.6.2 Datum Reference Frame (DRF)......................................................................31
2.7 TOLERANCE ACCUMULATION........................................................................33
2.7.1 Tolerance Accumulation within Features.......................................................33
2.7.2 Tolerance accumulation in Assembly system.................................................36
2.8 TOLERANCE ANALYSIS....................................................................................37
2.8.1 Sensitivity Analysis........................................................................................40
2.8.2 Variation Analysis..........................................................................................40
2.8.3 Contribution Analysis.....................................................................................42
2.8.4 Tolerance Stack up..........................................................................................43
2.8.5 Assembly Equation.........................................................................................47
2.8.6 Process Capability and General Tolerances....................................................48
2.9 TOLERANCE ALLOCATION..............................................................................50
2.10 CONSISTENCY OF TOLERANCE LOOPS.........................................................53
2.11 VECTORIAL DIMENSIONING AND TOLERANCING (VD&T)......................54
2.12 PRINCIPLES AND PRACTICES OF TOLERANCING.......................................57
2.13 CONCLUSION.......................................................................................................60
3 TOLERANCE MANAGEMENT IN AEC.................................................................61
3.1 AEC LITERATURE ON TOLERANCES..............................................................62
3.1.1 Deficiency in Present AEC Tolerance Research............................................63
3.2 ASSOCIATED AEC LITERATURE.....................................................................65
3.2.1 Constructability...............................................................................................65
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3.2.2 Concurrent Engineering (CE).........................................................................66
3.2.3 Quality in Construction (QiC)........................................................................68
3.2.4 Lean Construction...........................................................................................69
3.2.5 Conclusions.....................................................................................................72
4 CASE STUDY-BLEACHERS INSTALLATION......................................................74
4.1 BACKGROUND.....................................................................................................74
4.2 BLEACHER INSTALLATION: CURRENT PRACTICE.....................................75
4.3 PROBLEMS DOWNSTREAM..............................................................................82
4.4 POSSIBLE SOURCES OF VARIABILITY...........................................................84
4.5 PROACTIVE TOLERANCE VISUALIZATION..................................................86
4.6 PROCESS UNCERTAINTIES...............................................................................88
4.6.1 Variations of Process Constraints...................................................................88
4.7 TOLERANCE REPRENSENTATION AND TOLERANCE NETWORK...........90
4.8 DESIGN AND PROCESS TOLERANCE MAPPING BACKGROUND.............92
4.9 PRODUCT DESIGN TOLERANCE MAPPING...................................................93
4.9.1 Setup Mapping Area.......................................................................................93
4.9.2 Setup and Connect the Nodes.........................................................................94
4.9.3 Assign Values in the Tolerance Frames..........................................................96
4.9.4 Refine and Minimize Constraints...................................................................98
4.9.5 Identify, Evaluate and Check Loop Consistency............................................99
4.10 PROCESS TOLERANCE MAPPING..................................................................103
4.10.1 Process Capability Data................................................................................103
4.10.2 Process Mapping...........................................................................................103
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4.11 TOLERANCE ACCUMULATION IN BLEACHERS........................................107
4.11.1 Mechanism of Tolerance Propagation and Accumulation............................107
4.11.2 Worst Case Tolerance Accumulation...........................................................110
4.11.3 Interpretation and Discussion of Results......................................................121
4.12 LEAN TECHNIQUES AND WORK STRUCTURING - INTEGRATED
PRODUCT & PROCESS DESIGN......................................................................123
4.12.1 Decouple Dependent Activities....................................................................125
4.12.2 Product Standardization and Modularity......................................................127
4.12.3 Poka Yoke (Error Proofing) of Product and Process....................................129
4.12.4 New Product Development (NPD)...............................................................130
4.13 ABSORBING PRODUCT AND PROCESS VARIABILITY.............................132
4.14 RELIABILITY OF PROCESS TOLERANCE.....................................................134
4.15 VERIFICATION OF RESEARCH HYPOTHESES............................................135
4.16 RESEARCH CONTRIBUTIONS.........................................................................137
5 CONCLUSION...........................................................................................................140
6 FUTURE VALIDATION OF RESEARCH PROCEDURE AND FINDINGS.....143
7 FUTURE RESEARCH...............................................................................................145
REFERENCES....................................................................................................................146
APPENDIX 1.......................................................................................................................152
APPENDIX 2:......................................................................................................................153
APPENDIX 3:......................................................................................................................154
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APPENDIX 4:......................................................................................................................155
APPENDIX 5:......................................................................................................................156
APPENDIX 6.......................................................................................................................157
APPENDIX 7.......................................................................................................................158

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LIST OF FIGURES
Figure 1.9-1: Standard Geometric Tolerances (Henzold 1995)..............................................12
Figure 1.9-2: GD&T System (Henzold 1995)........................................................................13
Figure 1.9-3: VD&T System (Henzold 1995)........................................................................13
Figure 2.3.1-1: GD&T tolerances (Milberg 2006, based on Henzold 1995)..........................20
Figure 2.7.1-1: Linear tolerance accumulation between features within part (Based on
Milberg 2006).........................................................................................................................34
Figure 2.7.1-2: Linear accumulation between features with tolerance zone (Based on Milberg
2006).......................................................................................................................................36
Figure 2.7.2-1: Linear tolerance accumulation between features in assembly (Based on
Milberg 2006).........................................................................................................................37
Figure 2.8-1: Tolerance analysis (Drake 1999)......................................................................38
Figure 2.9-1: Tolerance specification by tolerance allocation- (Drake 1999)........................50
Figure 2.11-1: VD&T System (Milberg 2006, based on Henzold 1995)...............................55
Figure 4.1-1: Installed bleachers (Acharjee 2006)..................................................................74
Figure 4.2-1: Supporting frame arrangement for bleachers (Acharjee 2006).........................76
Figure 4.2-2: Concrete piers built over the concrete floor (Xu 2007)....................................77
Figure 4.2-3: Base plates set over the piers (Xu 2007)...........................................................78
Figure 4.2-4: Support frame over the piers (Xu 2007)...........................................................78
Figure 4.2-5: Cross bracings added to rear vertical support (Xu 2007)..................................79
Figure 4.2-6: Decking frames added to the support frame (Xu 2007)....................................79
Figure 4.2-7: Decking platforms erected on the decking frame (Xu 2007)............................80
Figure 4.2-8: Cover panels added to the support frames (Xu 2007).......................................80
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