Calibration of "Master Parts" Used as Gauges

Greetings,

Our plant uses several Master Parts to check production. These are "known" good parts used for simple fit tests against the production parts. In most cases, the production parts will mate with other parts that are the same type as the Master Part out in the field. There is a dimensional criteria to these. Additionally, the production parts are checked regularly using micrometers and other more formal measuring devices. The Master parts exist as a "Quick Check" that can be used by an operator. I am in the process of writing a procedure to document calibration (verification may be a better term) of these Master parts. What are your thoughts on what to verify? Also, the parts being made are about as low-tech as you can get. No moving parts, no circuits.

Thank you in advance.

G

I'd suggest that you would do the same dimensional checks on the "master part" as you would have done prior to having a master part. There is a hazard however. If the master part is made of the same material as the parts being mated to it, eventually the master part will be worn away and no longer functional as a check. May need to consider having a master part made of a tougher material than the production version - as long as that does not cause problems with the mating, or cause damage to the part being tested.

I would think about having the master parts sent out to a CMM service to verify the dimensions against wear.

There's nothing intrinsically wrong with using mating parts as a "quick check," but what you need to be concerned with is risk. What is the likelihood that using a mating part will result in erroneous information? How does wear affect the verification integrity? What happens when parts don't mate properly, and how is "properly" defined?

Steve Prevette said:

I'd suggest that you would do the same dimensional checks on the "master part" as you would have done prior to having a master part. There is a hazard however. If the master part is made of the same material as the parts being mated to it, eventually the master part will be worn away and no longer functional as a check. May need to consider having a master part made of a tougher material than the production version - as long as that does not cause problems with the mating, or cause damage to the part being tested.

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Good advice. Thank you.

outdoorsNW said:

I would think about having the master parts sent out to a CMM service to verify the dimensions against wear.

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Thank you.