%GRR tolerance analysis [GRR/(tolerance/6)]


Hope all has been keeping well! :)

I need some help to interpret an example of GRR results below.
I have always refer to the %GRR under the total variation analysis, and that result here shows 9.88% which is acceptable (< 10%).

How about the %GRR under the tolerance analysis [GRR/(tolerance/6)], which shows 15.83%? Does this need to fulfill the acceptance criteria of <10%?
How to interpret this result?
Any help or guidance is greatly appreciated.

Many thanks!

(I am unable to insert an image here, so I have manually type the formula & result into a table.)

Measurement Unit Analysis
% Total Variation Analysis
% Tolerance Analysis
Repeatability - Equipment Variation (EV)
EV = 0.00154
%EVv = 100 x [EV/TV]
= 8.22%
%EVt = 100 x [EV/(Tolerance/6)]
= 13.17%
Reproducibility - Appraiser Variation (AV)
AV = 0.00103
%AVv = 100 x [AV/TV]
= 5.49%
%AVt = 100 x [AV/(Tolerance/6)]
= 8.79%
Repeatability & Reproducibility (GRR)
GRR = 0.00185
%GRRv = 100 x [GRR/TV]
= 9.88%
%GRRt = 100 x [GRR/(Tolerance/6)]
= 15.83%
Part Variation (PV)
PV = 0.01860
%PVv = 100 x [PV/TV]
= 99.51%
%Pvt = 100 x [PV/(Tolerance/6)]
= 159.40%
Total Variation (TV)
TV = 0.01869
ndc = 1.41 x [PV/GRR]
= 14


Forum Moderator
It depends on the intended use for the measurement device. If you intend to use it for inspection to a tolerance, % Tolerance is the appropriate metric and the other metrics can be ignored. Whether 15.83% is acceptable or not depends on your situation. The MSA manual clearly states that results between 10% and 30% might be accepted given certain circumstances. If the measurement device will be used for SPC then %Total Variation should be used, and %Tolerance can be ignored. The only time when you should consider both metrics is when the measurement device will be used for both inspection and for SPC.
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