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Justifications for not performing MSA (Measurement System Analysis)

nhoJ

Registered
#1
Has anyone specified in their companies MSA procedures that certain devices such as rulers, micrometers, etc. were low risk due to all inspectors being certified quality technicians and therefore GR&R's would not be required for measurements made using said devices? Or specified GR&R's where not required on already established processes that had an established Cpk > 2.0?
 

hngrad1977

Starting to get Involved
#4
One question, you state you have an established process above. How do you know that with certainty? The old saying is "how do you know how good the part is if you don't know how good the gauge is being used to check it?" Old school
 

GRP

Involved In Discussions
#5
"how do you know how good the part is if you don't know how good the gauge is being used to check it?" Old school
Without studying the measurement system (MS) I would challenge the notion of having a Cpk > 2.0. Without checking the bias the Cpk could be off by an X amount, which could or not be significant.

But the Cp relates to process or tolerance alone. If that is > 2.0 and then you could infere that the MS is not too bad because the variation of the process + the variation of the MS gives a good Cp. You would not know if your parts are superb and your MS so so (or vice-versa), but you would know that what you end up observing (the combination of the both) yields and acceptable result.
 
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