The presentation explains the fundamentals of Measurement System Analysis (MSA) also known as Gage R&R Analysis.

1. Rajiv Iyer
Understanding Measurement System Analysis (MSA)
also known as Gage R&R Analysis

2. 2
Gage R&R Analysis – Fundamental Concepts
• Critical tool in
understanding capabilities
of any system used by
different operators for
measuring a part
• “R&R” stands for
Repeatability and
Reproducibility
• Core question to answer:
Is the gage/instrument
capable of distinguishing
between good and bad
units?

3. 3
Gage R&R Analysis - Methods
• Analysis of Variance (ANOVA) Method
• Estimates variability of each factor to
understand effect of each factor on the
response from the experiment
• Extended to gage R&R to identify if parts,
operators, or both have any effect or not
• Total %R&R estimated – to understand
contribution of each factor for variability
• x̄ & R Method
• Alternate method to conduct gage R&R
analysis
• For use when less trials are run, compared
to ANOVA
• Uses the average and range of the data to
estimate the %R&R value
• Does not provide details on factor
significance to the measurement like
ANOVA method

4. 4
Gage R&R Analysis – Guidelines
*Guidelines recommended by AIAG in 1990s
GRR Decision Comments
Under 10%
Generally considered to be an
acceptable measurement
system.
Recommended, especially useful when trying to sort or
classify parts or when tightened process control is required.
10% to 30%
May be acceptable for some
applications.
Decision should be based upon, for example, importance of
application measurement, cost of measurement device, and
cost of rework or repair. Should be approved by the customer.
Over 30% Considered to be unacceptable.
Every effort should be made to improve the measurement
system. This condition may be addressed by the use of an
appropriate measurement strategy; for example, using the
average result of several reading of the same part
characteristic in order to reduce final measurement variation.

5. 5
How Does Gage R&R Apply to Instron?
• Instron products – Used for running
destructive and non-destructive
materials testing
• Gage R&R can be classified into
two types: destructive gage R&R
and non-destructive gage R&R
• Non-destructive gage R&R
example: compression and stiffness
measurements of springs with
widely different stiffness.
• Destructive gage R&R example:
tension of different plastic
specimens (rigid, semi-rigid and
soft).
Note: It is highly recommended to choose parts or specimens that closely reflect the system’s
intended application.

6. 6
Type I Gage Study – P/T Ratio
• Used to investigate precision and
accuracy of a measurement system
without considering other sources
of variations (operators, parts)
• Simpler study used for verification
of pre-installed or old systems
• P/T Ratio – The precision-to-
tolerance ratio estimates how
precise the data is to the defined
tolerance or specification limits
• Highly valuable in production and
QC environments
• Guidelines for P/T ratio are the
same as the table on slide # 4
defined by AIAG
Reference 0.4268
Mean 0.42686167
StDev 0.000202571
6 × StDev (SV) 0.001215427
Tolerance (Tol) 0.017071
Basic Statistics
Bias 0.00006167
T 1.667376123
PValue 0.106
(Test Bias = 0)
Bias
Cg 1.40
Cgk 1.30
Capability
%Var(Repeatability) 7.12%
%Var(Repeatability and Bias) 7.67%
Gage name: Sample GRR
Date of study: Sample
Reported by: Rajiv Iyer
Tolerance: Sample
Misc: Sample
28252219161310741
0.4276
0.4272
0.4268
0.4264
0.4260
Observation
Response
Ref
Ref + 0.05 × Tol
Ref - 0.05 × Tol
Run Chart - Sample
Type 1 Gage Study - Sample Report

7. 7
For more information on Gage R&R
and how it relates to Instron systems,
read the whitepaper
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