YS Class in DFMEA & Process Control Measures



Hi All

I am a little stumped!

In my DFMEA I have a Sev 8, Occ 3, Det 3 that relates to leakage of an air valve. This does not call for a YS / YC.

The reason for occurrence 3 is that we have robustly captured the specification for leakage.
We are not design responsible for the valve. We specify our requirements as leak rate targets.
The suppliers focus would be bore size, bore depth, surface finish etc for the seal.

My concern is that I can imagine the suppliers machining process used to make the part, and if not performed with the correct controls I can see leakage occurring.

So my DFMEA has no YS for leakage - My design spec is good.
But the process could get it wrong, and the DFMEA doesn't drive the suppliers PFMEA / Control plan without the YS.

I feel that leakage should be cascaded to the supplier as a YS, but I only say this because I have knowledge of the process risks which will not always be the case across a team of engineers.

Any help for clarity here would be appreciated.



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A quick "Bump". My Thanks in advance to anyone who can help with this unanswered question. And, should you be browsing threads and it still has no reply, if you can help we will all appreciate it.
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