Gage R&R (Repeatability and Reproducibility) Study with one appraiser

[MSAFAI]

R&R study with one appraiser

Hi everybody,

Consider the actual situation (such as in a small company), where there is always ONE inspector performing some specific measurement with some specific instrument everyday. In other words, usually, there is no one else to perform that measurement.

Is it still necessary to perform a (hypothetical) 2 or 3 apprasier R&R study, or a Repeatability study would be sufficient?

Regards & Thanks on beforehand.

MSAFAI

 

[Atul Khandekar]

MSAFAI,

My question is: is there REALLY only one operator? I am sure you will have a contingency plan for a situation where s/he does not report to work for a week. You should include these alternative operators (may be the supervisors) in the R&R study.

Assuming that this is not possible, I think there are two ways you can address the issue:

1. Refer MSA manual: Appendix D; Gage R Study:
Take 1 part, 1 operator, measure multiple (> 10) times. Plot I/MR charts to assess stability. If data is stable, 100* (6 * sigma)/Tolerance gives you the P/T ratio or %repeatability. Note that this is only a preliminary determination of short-term repeatability. This method cannot be used for final gage acceptance without a more cpmplete MSA study.

2. If you are doing Stability Study, and if the measurement data is stable ( Xbar-R chart), the standard deviation of measurements can be used (in the above equation) as an approximation of repeatability of the measurement system.

 

[MSAFAI]

Re: R&R study with one appraiser

Atul,

You are absolutely right. There must be someone to cover for illness, etc, although occasionally.

As you suggested, we will include him in the R&R study.

Thanks for your help,
MSAFAI