2. Introduction
• What is a Gage R&R
• Definitions
• Standards that companies use
• Examples of Gage R&Rs
3. What will not be covered
• The Equations for Gage R&R
– There are many statistics programs
– Go to www.google.com and type in Gage
R&R and there are work sheets
5. What is a Gage R&R?
• A method to check whether a gage is
capable of making the appropriate
measurements.
• Doing an Analysis of Variation (ANOVA)
of a group of readings to ensure
measurement precision and reliability
• The gage is a constant
6. What is a Gage R&R?
• A measurement is characterized by
Location (accuracy, stability and linearity
metrics) and Spread (repeatability and
reproducibility).
• A Gage R&R measures spread
7. Definitions
• Variation
– the differences within a piece, from piece to piece,
measurement to measurement, and other variation
such as process step to process step, etc.
• Every process has variation including in
the measuring gage
• Want to make sure that variation in the
gage is acceptable
8. Definitions
• Accuracy
– Bias. Difference between an average of a
number of measurements and the true value
• Gage must be accurate
• Test for accuracy is calibration
• The Gage must be calibrated
9. Definitions
• Repeatability
– Precision. The ability to repeat the
measurements by the same operator at or
near the same time
• Reproducibility
– Reliability. The ability to reproduce the
measurements by different operators at
different times.
11. Standards
• What are some standards that companies
such as GE are using for acceptable
gages?
12. Standards
• For gages that are used to make pass/fail
decisions < 30% of the process variation
can come from the gage
• For gages that are used to measure
improvements in the process < 10% of the
process variation can come from the gage
20. Results
Gage name: Micrometer
Date of study:
Gage R&R (ANOVA) for Measurement Reported by: Dave Potty
Tolerance:
Misc:
Components of Variation By Sample
100 4.85
%Contribution
4.84
4.83
Percent
50 4.82
4.81
4.80
0 4.79
Gage R&R Repeat Reprod Part-to-Part Sample 1 2 3 4 5 6 7 8 9 10
R Chart by Operator By Operator
Greg Nick Roy 4.85
0.04
Sample Range
4.84
0.03 UCL=0.03183
4.83
0.02 4.82
R=0.01237 4.81
0.01
4.80
0.00 LCL=0
4.79
0 Operator Greg Nick Roy
Xbar Chart by Operator Operator*Sample Interaction
4.83 Greg Nick Roy Operator
Greg
UCL=4.825
ean
4.82 Nick
4.82
Average
Roy
Sample M
Mean=4.812
4.81 4.81
4.80 LCL=4.800 4.80
0 Sample 1 2 3 4 5 6 7 8 9 10
21. Example of a more complicated
Gage R&R
• We had a continuous measurement of
width of a flat wire
• We measure a standard 10 times and
compared the measurements
22. Calculation
T o ta l o f o b s e rv e d
W ith in p a r t V a r ia tio n V a r ia tio n
M e a s u r e m e n t V a r ia tio n
