a comparative study on tolerance analysis...

A Comparative Study on Tolerance Analysis Approaches

International Symposium on Robust Design 2014, Copenhagen, Denmark B. Schleich, N. Anwer, Z. Zhu, L. Qiao, L. Mathieu, S. Wartzack

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© LEHRSTUHL FÜR KONSTRUKTIONSTECHNIK Friedrich-Alexander-Universität Erlangen-Nürnberg Prof. Dr.-Ing. Sandro Wartzack

A Comparative Study on TA Approaches Outline

Motivation – Geometric Variations Management as a Branch of Robust Design

Proprietary Tolerance Analysis Approach The Concept of Skin Model Shapes and

the Tolerance Analysis based thereon Case Studies:

GD&T Standards and Assembly Sequence Conclusion and Outlook

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noise factor

geometric variations management variation

tagu

chi

six

sigm

a

robustness

simulation process capability

tolerance design

mean shift robust design methodology

sensitivity analysis

inse

nsiti

vity

concept design

FOR

M

availability

reliability

safety

dependability disturbance

SORM

quality

functional requirements

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Motivation Geometric Variations Management as a Part of RD

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Ref.: Arvidsson&Gremyr2008, Reuter2000

noise factor

geometric variations management variation

tagu

chi

six

sigm

a

robustness

simulation process capability

tolerance design

mean shift robust design methodology

sensitivity analysis

inse

nsiti

vity

concept design

FOR

M

availability

reliability

safety

dependability disturbance

SORM

quality

functional requirements

Robust Design Methodology is understood as systematic efforts to achieve insensitivity to noise factors. These efforts are founded on an awareness of variation and can be applied in all stages of product design.

Robust Design Methodology

Manufacturing and Assembly

Inspection and Quality Control

Product Design

Geometric Variations Management

Tolerance Synthesis Tolerance Analysis

Geometric Requirements Tolerance Specification

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Non-robust Design

Robust Design

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Proprietary CAT software Tolerance Analysis Approach

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Tolerance Assignment

in CAD

Definition of Tolerances

Definition of Assembly

Tolerance Simulation

Result Visualization

Proprietary Tolerance Simulation Tool

Workflow Information Transfer

Specification of (F)KCs

1. 34,1%

27,8%

19,5%

12%

2.

3.

4.

1 2

1 2 ft

par A pos A

A fb

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Ref.: Prisco & Giorleo 2002, Shah et al. 2007, Mazur et al. 2011, Clozel et al. 2012

Definition of the assembly CAD models and specification of tolerance types and values as well as definition of their individual distributions. 1.

Definition of the assembly sequence (moves), the part/features relative positioning and the mating conditions (e. g. planar or cylindrical).

2.

Specification of Key Characteristics (KCs) and geometric functional requirements, such as gaps or clearances.

3.

Simulation of the effect of part tolerances on KCs using a worst-case or statistical approach (methods such as Monte Carlo simulation are used) employing a tolerance simulation model.

4. Analysis of the outcome data and identification of the main contributors to evaluate their sensitivity to the KCs and the tolerance design robustness. This step is supported by visualization techniques, such as histograms or KC plots.

5.

Tolerance Representation for CAT

Consideration only of rotational and translational feature defects!

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© LEHRSTUHL FÜR KONSTRUKTIONSTECHNIK Friedrich-Alexander-Universität Erlangen-Nürnberg Prof. Dr.-Ing. Sandro Wartzack 5

Skin Model Shapes Fundamentals and Concept

Ref.: 2007Mathieu&Ballu, 2008Dantan,Ballu&Mathieu, 2011Ballu

Nominal Model Skin Model Skin Model Shapes

The Skin Model Model of the physical

interface between the workpiece and its environment Exists in the mind of the

product developer Can be used to represent

the part in the analysis & allocation of tolerances

Skin Model Shapes Skin Model is an Infinite

Model No Possibility for

Identification or Simulation Translation and

Operationalization to a Finite Model

Intrinsic Characteristic Situation Characteristics…

Partition, Filtration, Extraction, …

GeoSpelling defines a Specification as a…

CHARACTERISTIC

GEOMETRIC FEATURES

…Condition

SKIN Model Operations

on a

defined from

by created from

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Skin Model Shapes Tolerance Analysis Approach

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Nominal Model

Skin Model Shape Generation

Skin Model Shapes

Pre-Processing

Assembly Simulation Model

Definition of the Assembly Process

Assembly Modelling

Relative Positioning

Assembly Position

Skin Model Shape Preparation

Contact Quality Evaluation

Comparison for Conformance

Post-Processing

1 2

1. 34,1%

27,8%

19,5%

12%

2.

3.

4.

Skin Model Shape Generation Prediction Stage: Modelling of systematic and random deviations Observation Stage: Results from Simulations or Measurement Data

SMS Preparation Partition of SMS using GeoSpelling operations

Assembly Process Definition Define the assembly process and the assembly sequence

Relative Positioning Employ constrained registration approaches for the relative positioning of Skin Model Shapes

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Case Study 1 Consideration of GD&T Standards

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E F G

C A B

D

80

E’

A’

F’ G’

C’ B’

D’

10

50

40

ft par A pos A

A fb

50

α β

Considered Geometric Deviations: Geometric Deviations are visible on the Block Flatness, Parallelism & Position Tolerances ft=fb=0.05, par=0.1, pos=0.2 Gaussian Distribution (Six Sigma)

No Deviations of the Plates Assembly Sequence: Straight 3-Point Moves

1. Block on first Plate 2. Plate on Block

Quick View

Ref.: 2001Anselmetti&Mathieu

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Case Study 1 Consideration of GD&T Standards – Results

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Findings Mean Shift between the proprietary CAT tool and the approach based on SMS for dimensional FKCs

Prop. CAT tool overestimates the effects for the tilt angles

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Case Study 2 Consideration of the Assembly Sequence

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40 A ft

ft

ft B pos A B

per A

ft pos C D

ft per C

D

30 C ft

1 2 2 1

x

y

Considered Geometric Deviations: Geometric Deviations are visible on the first

part (grey) and on the second part (blue) Flatness, Perpendicularity & Position Tolerances ft=fb=0.05, per=0.2, pos(A|B)=1.0, pos(C|D)=0.4 Gaussian Distribution (Six Sigma)

Assembly Sequence: Scenario 1: Primary contact (3 points) in the y-direction,

secondary contact (2 points) in the x-direction Scenario 2: Primary contact (3 points) in the x-direction,

secondary contact (2 points) in the y-direction

Quick View

Ref.: 2001Anselmetti&Mathieu

s

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Case Study 2 Consideration of the Assembly Sequence – Results

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Findings Mean Shift between the proprietary CAT tool and the approach based on SMS for dimensional FKCs

Little Effect of the Assembly Sequence on the minimal Gap s

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Conclusion and Outlook General Remarks and Further Research Challenges

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Correlation length: 1 Correlation length: 5 Correlation length: 10

Conclusion Qualitative comparison of the tolerance analysis approaches

employing proprietary CAT tools and based on Skin Model Shapes

Quantitative comparison of the approaches with two case studies Slight differences between the approaches can be observed Algorithms implemented in proprietary CAT tools are a black box

Integration of results obtained from computer aided manufacturing tools Consideration of various physical phenomena, such as gravity and friction In-depth analysis of the effects of various deviation parameters

Outlook

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Summer School Tolerance Management FAU Erlangen-Nürnberg, September 2015

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2nd Summer School Tolerance Management at the KTmfk Exchange between Industry, Research and Students in Tolerance Management Three Day Programme with Industry Cases, Elevator-Pitches and Workshops September 2015 at the Chair of Engineering Design KTmfk, Friedrich-Alexander-

University Erlangen-Nürnberg

Topics: Methods and Tools for virtual

Geometric Variations Management & RD Recent Trends in Research and Industry

Further Information: http://www.mfk.fau.de/toleranzen

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a comparative study on tolerance analysis...

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