What to Check - Set Up vs. In Process Inspections

Golfman25

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So we are debating reworking our inspection criteria. Trying to come up with something workable but robust. So here goes:

Assume each part we make starts off with a First Article Inspection - a complete dimensional layout, including notes. Usually done before production, when the tooling to make the part is made and approved. Very comprehensive. We are good with that.

Next is a setup inspection. Tooling is setup and the initial samples are approved to run. This is where we are struggling/debating. How comprehensive should our inspection be? Whole print, just the "important" dimensions we'll check during production, or something in between?

Then we have regular old in process inspection. We have this down reasonably well. We check those dimensions which are critical, important or otherwise subject to variation during the run.

And Final, mirrors the in process inspection.

Looking for any thoughts, approaches, etc. Thanks in advance.
 

Michael_M

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One of the problems we have during setup inspection and in-process inspection is not the critical dimensions or the tight tolerance dimensions, the operators check these frequently. We have problems with dimensions (such as chamfers and Radi) that are ±.010 because they are such open tolerances people do not check them. Typically when they are found, it turns out to be a full days productions or more.

To combat this, and yes, it seems like combat, we require in-process inspection on open tolerances as well tight tolerances, just not as frequent.
 

Bev D

Heretical Statistician
Leader
Super Moderator
It really depends on your Customer, how they feel about the dimensions, features and properties that are specified but are not noted as critical or important and how much risk you are willing to tolerate.

A very well characterized set of tooling and processes (operator, equipment and environment) and materials reduces the need for inspection...

Without understanding the above, the only I can offer is uninformed opinion.
 

Golfman25

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One of the problems we have during setup inspection and in-process inspection is not the critical dimensions or the tight tolerance dimensions, the operators check these frequently. We have problems with dimensions (such as chamfers and Radi) that are ±.010 because they are such open tolerances people do not check them. Typically when they are found, it turns out to be a full days productions or more.

To combat this, and yes, it seems like combat, we require in-process inspection on open tolerances as well tight tolerances, just not as frequent.

That's similar to the issue we face. Usually there are a few dimensions which aren't all that important and are difficult to check -- you may have to cut parts, etc. If we do that for every setup (especially for a few hundred parts), it can bog the whole process down. And even if they where "out" there may not be anything we can do anyway.

Some type of frequency check may work -- something to think about. Thanks.
 

Michael_M

Trusted Information Resource
That's similar to the issue we face. Usually there are a few dimensions which aren't all that important and are difficult to check -- you may have to cut parts, etc. If we do that for every setup (especially for a few hundred parts), it can bog the whole process down. And even if they where "out" there may not be anything we can do anyway.

Some type of frequency check may work -- something to think about. Thanks.

For (some) internal Dimensions we use flexbar repo rubber but this takes a bit to setup and does not work well for constant dimensional checks but it is better than cutting a part. If possible, we try to set up the machine so we can use one dimension to verify another dimension: one tool runs two diameters so if one diameter is good, the other (theoretically) should be good as well.
 

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