As that I have neither the MSA manual or the book mentioned in my library, perhaps I am completely off the mark here, so if I am, please, someone let me know.

As you can see, in the MSA manual issued by the Big Three, calculation of gage R&R uses total variation instead of tolerance.

The R&R studies I have done include variation as:

SIGMA(ev) = Equipment Variation (Repeatability)

SIGMA(ov) = Operator Variation (Reproducibility)

SIGMA(r&r) = Total Variation (Repeatability & Reproducibility)

This is the variation within the study itself. From that, it should be determined how this variation affects measurement uncertainty, usually by Percent Tolerance Consumed, as follows:

Percent Tolerance Consumed by Repeatability (PTCR)

Percent Tolerance Consumed by Measurements (PTCM)

Percent Tolerance Consumed by inspection Capability (PTCC)

The criteria for PTCC is normally:

< 10% Acceptable

> 10% and < 25 % Marginal

> 25% Not Acceptable

Of course, the above is from using the range method. The ANOVA method is a bit more difficult. Somewhere, I have a paper I did in the past that explains these concepts in more detail. I will try to find, dust off and forward. Marc’s MSA presentation in the pdf zone also does a good job of presenting this information.

Regards,

Don