I was hoping to get feedback on how other facilities conduct r&r studies on surface finish gages. what I am really interested in is if you use a series of controlled patches with a known surface finish that covers the range of your surface finish spec, or if you use actual production parts.
When we conduct r&r studies on our hardness testers we use hardness test blocks that cover the range of our hardness spec. My goal is to convince our quality manager that we should use surface finish patches with a known surface finish that covers our surface finish spec as well. As opposed, to using production parts with unknown surface finish variability within the parts.
I agree with using production parts for our dimensional type gage r&r studies.
However, I think that a known surface finish patch should be used for r&r studies on surface finish.
Just intertested in how other people may do it, and any suggestions as to how to argue my point to our quality manager.
Hope I :thanx: didn't ramble on too much. I work nights and i just got in..... so I'm all hyped up on caffeine!!!!!!!!!!!!!!!!!!!!!!

Welcome to the Cove :bigwave:

I have always considered using a profilometer as a destructive type of test (because you can't retest the same spot) and have used standards, or patches, as you described to perform Gage R&Rs. I'm not sure how my logic applies to harder metals as we produce aluminum (fairly soft) die castings. Right or wrong I've not had any issues with customers or auditors.

Welcome to the Cove :bigwave:

I have always considered using a profilometer as a destructive type of test (because you can't retest the same spot) and have used standards, or patches, as you described to perform Gage R&Rs. I'm not sure how my logic applies to harder metals as we produce aluminum (fairly soft) die castings. Right or wrong I've not had any issues with customers or auditors.
I agree. The only way that using production parts would be truly useful is if you could know the true value and carefully control the location of testing. Neither is practical, or even possible in some cases. Because the primary source of error in this sort of inspection is relative to the gage and/or operator, it makes good sense to use controlled standards for the analysis.

I have no experience with a profilometer, hence a few questions:

How expensive (or not) is it to obtain controlled surface finish patches with a known surface finish that covers your spec?

If you suspect too much within-part variation, has a study been conducted on your production parts just to ascertain if there is a significant variation. If there isn't too much 'within-part' variation, the re-testing can possibly be done by taking the next trial very close to the first one. This could work even with softer materials where there would be scratches/trenching.

Inspite of within-part variation if the GRR is OK, you should not have any issues.