Audit finding for challenge parts

[jimmymustang06]

A recent finding was "The organization does not always ensure evidence of all Error-Proofing requirements." because we don't address the use of challenge parts in leak-decay test for our coiled aluminum tubing. I can't believe this has slipped passed us for over a decade, but here we are. I can easily add the challenge parts to our PFMEA and control plans, but I'm not sure exactly of the detail needed. 10.2.4 states "..... . Details of the method used shall be documented in the process risk analysis (such as PFMEA) and test frequencies shall be documented in the control plan. The process shall include the testing of error-proofing devices for failure or simulated failure. Records shall be maintained. Challenge parts, when used, shall be identified, controlled, verified, and calibrated where feasible. Error-proofing device failures shall have a reaction plan."

Our challenge parts are basically go/no go gages, consisting of 2 tubes, 1 with a very small hole (0.015") in it and 1 without a hole. The tubes are connected to the PLC controlled leak-decay system. Using the tube with the hole in it, the system should signify a "passed" test, as there is no leak. If the tube used has the hole in it, the system should "fail" the test, of course because there is a hole (leak).

We use these challenge parts to verify our leak-decay system every 6 months. I'm not sure how I would verify the verification tubes themselves? Or, do I even need to verify these gages (tubes)?

 

[Sidney Vianna]

These are test fixture standards, not production parts. And should be handled as such.

Unless I misunderstood you.

 

[Golfman25]

I am not understanding how this is "error-proofing" vs. testing/inspection? Does every tube get tested?

 

[jimmymustang06]

I am not understanding how this is "error-proofing" vs. testing/inspection? Does every tube get tested?

Every tubing coil (2,000 feet+) is tested through the leak-decay system. Every 6 months we attach these test tubes (15") to verify that the leak-decay system can still correctly identify a leak. We're not worried about the size of the hole, only that it detects a leak, which it does daily. The auditor considered these test tubes as challenge parts, which we never really have, hence not adding them to PFMEAs and Control Plans. But I can add them, I'm just not sure what I say about them in those documents.

 

[jimmymustang06]

I am not understanding how this is "error-proofing" vs. testing/inspection? Does every tube get tested?

I guess I shouldn't call it a leak-decay test, it's really a pressure-decay test. At any rate, with our tubes (1 with a hole, 1 without a hole), we are just verifying that the pressure-decay test is functioning correctly. The system MUST fail one tube and MUST pass the other.

 

[Sebastian]

Do you have specification for challenging parts?
How to discrim OK from NOK part?
Does exist scenario where time passes, OK sample become NOK and NOK becomes OK?
Any risk analysis in this case, resulting in setting verification in control plan?

P.S.
I love this "over decade" and requirement is 7 years old

 

[jimmymustang06]

Do you have specification for challenging parts?
How to discrim OK from NOK part?
Does exist scenario where time passes, OK sample become NOK and NOK becomes OK?
Any risk analysis in this case, resulting in setting verification in control plan?

P.S.
I love this "over decade" and requirement is 7 years old

The specification for the challenge parts is only that one has a hole and the other does not. And, that the one that does have the hole results in the pressure-decay system identifying it a a failure and the other as a passing test. Each test tube has its own Gage ID, as which tube it is listed on the tube itself as "Pass" or "Fail". We never considered these as challenge parts, but as a reference standard to verify the pressure-decay system. When I said it slipped past us for a decade, I thought that we didn't even address the leak test, but I did find where it is listed in the PFMEAs and Control Plans, we just didn't list the standards we used to verify the test. I'm still not real sure that these should be considered "challenge parts".

 

[Golfman25]

Every tubing coil (2,000 feet+) is tested through the leak-decay system. Every 6 months we attach these test tubes (15") to verify that the leak-decay system can still correctly identify a leak. We're not worried about the size of the hole, only that it detects a leak, which it does daily. The auditor considered these test tubes as challenge parts, which we never really have, hence not adding them to PFMEAs and Control Plans. But I can add them, I'm just not sure what I say about them in those documents.

My own opinion is that it's a stretch to call these "challenge" parts. You're basically verifying/calibrating your "leak down" test. Not sure how that is error proofing (per the IATF def -- process design to prevent manufacture of non-conforming products) vs error detection. Your tube is made, and I assume scrapped if it fails the test. If it was actual "error proofing" the leak would never happen, no? So I can see how this went "uncovered" for some time. You're bigger issue may be answering the "root cause" questions in your response to the auditor.

 

[jimmymustang06]

My own opinion is that it's a stretch to call these "challenge" parts. You're basically verifying/calibrating your "leak down" test. Not sure how that is error proofing (per the IATF def -- process design to prevent manufacture of non-conforming products) vs error detection. Your tube is made, and I assume scrapped if it fails the test. If it was actual "error proofing" the leak would never happen, no? So I can see how this went "uncovered" for some time. You're bigger issue may be answering the "root cause" questions in your response to the auditor.

Yes, you're understanding it exactly how we've understood it for the last 40 years under qs9000, TS, and now IATF. This is more of a process designed to prevent shipping a part with a leak. We built the system because the tubing has a very thin wall and there are a host of issues that can develop into a leak. Our processes utilizes methods where even a scratch may lead to a leak; and this is aluminum, it's scratched easily. The system works; we ship over 3 million lbs a month and a customer complaint of a leak is extremely rare because we catch all of them in house. I want to just appease this auditor and add the gages in as challenge parts, but like you say, this isn't error proofing, to try and make it into that causes a problem in the verbiage I would use in the documents.

 

[Sebastian]

Form-dependent position prevention control

The AIAG-VDA 1st ed. FMEA manual lists "form-dependent position" as a production process prevention control (p. 104). Can anyone explain what this is referring to?

elsmar.com

Diameter or dirt accumulating inside hole is not your point of interest I guess.
You rely on machine - when once test with NOK sample would end with OK result, then analysis will start.
"Details of the method used shall be documented in the process risk analysis (such as PFMEA) [...] Challenge parts, when used, shall be identified, controlled, verified, and calibrated where feasible. Error-proofing device failures shall have a reaction plan"
So how it is defined in your PFMEA?
Leakage tested with test machine. Process start is preceded by verification of test machine reliability, using challenge parts where NOK has ANY quantity of holes and hole(s) have ANY diameter. I guess not, so how challenge part is verified before used for test machine verification?

Reverse PFMEA was established to confront PFMEA team imaginations related to process control methods with reality.

I was working for company where challenge parts had "best before" dates defined, because after some time spent on production, NOK samples transformed into OK ones. Rubber specifics.

"Decade" was not meant to offend you.
It was comment to 3rd party auditors' performance.