Martin Gibson

Report
ISO/TS 16949:2009(E) and
AIAG MSA 4th edn. (2010)
Martin Gibson CStat, CSci, MSc, MBB
AQUIST Consulting
[email protected]
© M G Gibson 2010
RSS Destructive Testing MSA
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Making sense of MSA
 Do you know how accurate and precise your measurement and
test equipment are?
 Do you suspect that good work is sometimes condemned as bad
simply because of uncertainty in the measurement system; is
bad work ever released as good?
 Do you know the cost of non-capable measurement systems?
 Do you realise how important it is to understand measurement
systems uncertainty?
 Does your auditor share your understanding of measurement
systems?
 What can you do about it?
© M G Gibson 2014
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ISO/TS 16949:2009(E)
7.6.1 Measurement System Analysis
 Statistical studies shall be conducted to analyse the variation
present in the results of each type of measuring and test
equipment system.
 ... applies to measurement systems in the control plan.
 ... analytical methods and acceptance criteria used shall
conform to those in customer reference manuals on MSA.
 Other analytical methods and acceptance criteria may be used
if approved by the customer.
Questions:
 What is the operational definition of statistical studies?
 Do organisations, auditors, quality mangers understand statistical
studies?
 Why do auditors ask?, “Can you show me GR&R studies for each type of
measuring and test equipment system referenced in the control plan?”
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ISO/TS 16949 Scheme Update
IF SMMT Webinar, 5 Nov. 2013
Common problems found in ISO/TS16949 audits
 Calibration and MSA (7.6 and 7.6.1)
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Definition of Laboratory scope
Control of external laboratories
Traceability to national or international standards
MSA not done for all types of measuring systems
MSA only considering gauge R and R
Questions:
1. Why is MSA regarded as GR&R?
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Ford Motor Company MSA requirements (2009)
4.35 (ISO/TS 16949 cl. 7.6.1)
All gauges used for checking Ford components/parts per
the control plan shall have a gauge R&R performed in
accordance with the appropriate methods described by
the latest AIAG MSA to determine measurement
capability.
 Variable gauge studies should utilize 10 parts, 3 operators & 3
trials
 Attribute gauge studies should utilize 50 parts, 3 operators & 3
trials
Questions:
1. Are some Customers leading the thinking?
2. Why just limited to products?
3. What are your Customer expectations?
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Measurement System Variation
Observed Variation = Process Variation + Measurement System Variation
Bias
Accuracy
Linearity
Measurement
System
Variation
Calibration
Stability
Repeatability
Precision
Gauge R&R
Reproducibility
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AIAG MSA 4th edn. (2010)
 Accuracy, Bias, Stability, Linearity, Precision, Repeatability,
Reproducibility, GR&R
 Attributes, Variables, & non-replicable data considered
 Variables GR&R study
 10 parts, 3 operators, 3 measurements

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Parts chosen from 80% of tolerance
Destructive testing requires 90 parts from a homogeneous batch
 Three analytical methods:
Range – basic analysis, no estimates of R&R
2. Average & Range – provides estimates of R&R
3. ANOVA – preferred, estimates of parts, appraisers, parts*operators
interaction, replication error due to gauge
Question:
1. Do organisations, auditors, quality mangers understand MSA?
1.
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AIAG ANOVA Models
 Crossed vs. Nested
 Y ijk = μ + Operator i + Part j + (Operator*Part) ij + ε k(ij)
 Y ijk =  + Operator i + Part j(i) +  (ij)k
 Crossed vs. Nested?
 See Barrentine, Moen, Nolan & Provost, Bower, Burdick, Skrivanek
 Fixed vs. mixed effects models?
 Software?
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MTB V16+ includes fixed, mixed effects, enhanced models, pooled
standard deviation approach not included.
SPC for Excel – fixed effects
Other software packages?
Question:

Do organisations, auditors, quality mangers understand ANOVA?
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GR&R Variables Data Acceptance Criteria
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% Contribution
 Measurement System Variation as a percentage of Total Observed
Process Variation using variances (additive)
% Study Variation
 Measurement System Standard Deviation as a percentage of Total
observed process standard deviation (not additive)
% Tolerance
 Measurement Error as a percentage of Tolerance
Number of Distinct Categories (ndc)
 Measures the resolution of the scale
% Contribution

% Study Variation
% Tolerance
ndc
> 9% Unacceptable
> 30% Unacceptable
> 30% Unacceptable
< 5 Unacceptable
2-9% Acceptable
11-30% Acceptable
11-30% Acceptable
5-10 Acceptable
< 1% Good
< 10% Good
< 10% Good
> 10 Good
Do organisations, auditors, quality mangers understand the metrics?
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Non-replicable GR&R case study (Anon, 2002)
 Ensure that all the conditions surrounding the
measurement testing atmosphere are:
 defined, standardized and controlled
 appraisers should be similarly qualified and trained
 lighting should be adequate and consistently controlled
 work instructions should be detailed and operationally
defined
 environmental conditions should be controlled to an
adequate degree
 equipment should be properly maintained and calibrated,
failure modes understood, etc.
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Non-replicable GR&R case study (Anon, 2002)
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
If the overall process appears to be stable & capable, and all
the surrounding pre-requisites have been met, it may not
make sense to spend the effort to do a non-replicable study
since the overall capability includes measurement error – if
the total product variation and location is OK, the
measurement system may be considered acceptable.
Ironically high Cp / Cpk gives poor ndc!
Question:
1. Do organisations, auditors, quality mangers understand this concept?
AIAG FAQs response:
 If your process is stable and capable, the spread of this acceptable
process distribution includes your measurement error. There may be no
need to study your measurement error from a purely "acceptability"
viewpoint.’
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Questions for Making sense of MSA
 What is the operational definition of statistical studies?
 Do organisations, auditors, quality mangers understand






statistical studies?
Why do auditors ask for GR&R studies?
Why is MSA regarded as GR&R?
Are (some) Customers leading the thinking?
Why is MSA limited to products?
Do you know your Customer expectations?
Do organisations, auditors, quality mangers understand?

MSA, ANOVA, crossed vs. nested, fixed vs. mixed models, metrics, high
Cp/Cpk gives low ndc?
 Is MSA seen just as a QMS requirement or a true part of
continuous improvement?
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References
 AIAG Measurement System Analysis, 4th edn., (2010)
 Anon. Non-replicable GR&R case study, (circa 2002)
 Barrentine, Concepts for R&R Studies, 2nd edn., ASQ, (2003)
 Bower, A Comment on MSA with Destructive Testing, (2004) ; see also
keithbower.com
 Gorman & Bower, Measurement Systems Analysis and Destructive Testing,
ASQ Six Sigma Forum Magazine, (August 2002, Vol. 1, No. 4)
 Burdick, Borror & Montgomery, A review of methods for measurement
systems capability analysis; JQT, 35(4): 342-354, (2003)
 Burdick, Borror & Montgomery, Design & Analysis of Gauge R&R Studies,
SIAM, ASA, (2005)
 Moen, Nolan & Provost, “using a Nested Design for quantifying a destructive
test” in Improving Quality Through Planned Experimentation, McGraw-Hill;
1st edn., (1991)
 Skrivanek, How to conduct an MSA when the part is destroyed during
measurement, moresteam.com/whitepapers/nested-gage-rr.pdf
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