MSA 3rd Attribute GR&R (Gage R&R), no operators - Air decay test systems

[Karen Beth]

We have air decay test systems where the casting is fixtured automatically (no operator variation) and we are trying to screen 6cc max leaks. We are trying to determine the best, most straight forward, method for GR&R. We plug in calibrated orifices to introduce known leaks to test the equipment rather than having known leaking reference pieces. I thought the Analytic Method on pg 135 of MSA 3rd would be the correct approach but the the discrimination required to achieve the number of accepts is too fine for our process. Short study from old 2nd ed. MSA is no longer acceptable in 3rd ed and Attribute Study in 3rd has 3 appraisers x 3 trials x 50 samples. Can someone help us determine the best study? We have several stations which is why I say best but most expedient. Thank You!!!

 

[Rob Nix]

Since you have several stations, use the stations as different "Appraisers", and then do an attribute 3 x 3 x 50 study, i.e. 3 stations, 3 repeats, 50 parts.

This will give you your repeatability, but also an indication of the differences between the stations (ergo "reproducibility").

I hope that helps.

 

[Howard Atkins]

See these links we have had similar discussions

https://elsmar.com/elsmarqualityforum/threads/7637/

https://elsmar.com/elsmarqualityforum/threads/7838/

 

[Karen Beth]

Thanks. I need to clarify that the stations are not checking the same cavity therefore (I would think) need independent evaluation. I shyed away from the 3 X 3 X 50 due to the number of trials required (hoping for a shorter route) but also according to the MSA, the known reference values of the 50 parts are required. In our case, that would be one 6cc leak orifice not 50 individual readings. Am I off track? Thanks again.....