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#124 - 04/18/05 10:55 AM Acceptance Tests - strips before & after peen
hwenzel Offline

Registered: 04/18/05
Posts: 1
Loc: Los Angeles, CA
We peen some aluminum parts (non-aerospace) that are peened 6-12N using AGB-18 glass bead. There are several parts, but for the sake of this story, let's say we have part A and part B.

For part A, the operator runs a set of Almen strips before processing, and a 2nd set after processing. He's now ready to run part B. He was trained by me to do the same thing, run a new set of strips before and after processing. However, someone decided that part A and B are "similar enough" and that they could be treated as one "lot" of parts and therefore one set of strips (before and after) would suffice for both parts. This saves them 10-15 minutes of time.

I don't agree with this thinking. We keep the strips for our customer should they ever want evidence of peening intensity, but now I've got no "after" set of strips for part A, and no "before" set of strips for part B. The paperwork is there, and it's all in the logbook, but I've got no hard evidence.

AMS2430 sect 4.2.1 states that "intensity verification shall be performed at the beginning and, for lot sizes greater than one, at the end of each lot or every 8 hours, whichever is less."

So I guess it's how you interpret the meaning of a "lot". Sect. 4.3 helps define this a little, and sort of supports their thinking, but I still don't like it. Can someone help me out here?

#125 - 04/18/05 03:57 PM Re: Acceptance Tests - strips before & after peen
Walter Offline

Registered: 05/03/99
Posts: 160
Loc: East Hartford, CT, USA
You state that you keep the test strips on file in the event your customer would like to review them. Are you aware that Test Strips overtime will relax? Depending on how close your are to .006N you may find your strips out of tolerance at some point in the future.

In AMS 2430 section 4.3 a lot of parts can be any group of different part numbers as long as the intensity is verified by the same fixture,set-up, machine, machine parameters and in increments of not more than 8 hours of machine operation.

My suggestion to you would be to design an Almen Test Fixture that represents all the intensity verification areas for the entire family of parts you process. Then record the beginning strips, ending and or 8 hour in your logs as you are doing now. Then send all the test strips to your customer with the parts when shipped.

#126 - 04/20/05 08:58 AM Re: Acceptance Tests - strips before & after peen
E.Vazquez Offline

Registered: 03/15/05
Posts: 6
I agree with Walter. The hard evidence, will not last forever.
However, you should ask your customer to confirm that you are allowed to treat A and B parts as a lot. If not, you will have to specify it in your shop.

Good luck.


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