posted 30 July 1999 01:47 PM               

From: [email protected] (Kevin Johnson)
Subject: RE: MSA /Staples/Templeton/Johnson

Patricia,

Regarding your message below,

> From: Patricia Staples
> Subject: Q: MSA /Staples
>
> Has anyone heard of a requirement within the MSA that the 10 pieces checked
> for R&R have to be within spec?
> My customer said that my R&R was incorrect because I was checking parts
> that were out of spec.
> I told him that I needed to know that my gage was repeatable throughout
> the spec and below the spec. Any comments?
>

The important range to test across is not spec, but rather the range of product variation the instrument will see. You will want to know the components of variability across all "pieces" you will be measuring with this device. If all you product is always in spec, then maybe spec range is meaningful, but only beacause this is the range of the product, not just because of the spec range itself.

However, having said that, it is possible that, for a particular device and product, that the variability could more (or less) outside the spec than within it. So, the R&R numbers could look better or worse, depending on this range. And, this could concern the customer.

I understand your position clearly. I do not really understand the customer's. Do they understand the funamentals behind MSA?