PFMEA

Milas

Involved In Discussions
Hi

Some questions on PFMEA, which I would be grateful if someone got back to me on:

Q1) When there is more than one Potential cause /mechanism of failure, for a given failure mode, should they be listed in the same cell in order of severity or, should they be listed in separate cells?

Q2) How long should be allowed to complete the recommended actions including the effectiveness of those actions ?

Q3) Once the effectiveness of the recommended action has been verified and the RPN score re-evaluated. Does the recommended action and re-evaluated RPN Score, overwrite the original RPN Score and Control prevention ?

Thanks
 

Miner

Forum Moderator
Leader
Admin
Q1) If multiple causes, each occurring by itself, can result in the failure mode occurring in an OR relationship, list each in its own cell. If multiple causes must act together in an AND relationship for the failure mode to occur, list them in the same cell.
Q2) The time allowed needs to be realistic according to the recommended action. Ideally it should be completed prior to the start of production but this will not always be possible. In that case, you may need to consider some type of interim actions until it can be completed.
Q3) Not immediately. The new scores are entered into the second set of SOD columns to the right of the recommended actions. The next time a PFMEA is done for a new product, these scores can be transferred to the center SOD columns.
 

Bev D

Heretical Statistician
Leader
Super Moderator
Q1: each failure has a single severity (this is regardless of occurence); each cause has may have a separate probability or frequency of occurence (MIner is spot on regarding the AND/OR relationship) and should be in separate cells if they are independent (oOr relationship).

Q3: it is always best to retain the historical status of a PFMEA. This can be done by revision level or by by moving each RPN put to the right. As Miner stated…
 
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