A
alan1jones
Has anybody got any experience of this?
Thanks Jim,Have a look at this thread: P-diagram in FMEA preparation - What does the "P" stand for in "P-diagram"?.
Hope this helps.
It does seem to be a speedier and more logical way to pick up failure modes and causes, instead of moving down an FMEA line by line. I'm just not sure how to translate the p-diagram into an FMEA.Is it worth doing the P-diagram before an FMEA? What is the "value" that you would get out of it?
The value of any analytical process lies in the fact that it either causes you to think or not.
Functional blocks provide you with the overview of the big picture.
It answers the questions of :
What is the environment?
What are the interfaces?
How do they generically interface?
What are the regulatory requirements?
Who owns what?
Still there is a lot of room for needed improvement.
The P-Diagram attacks a subset of the elements in the Functional Block causing you to break these interfaces down and analyze them at a lower level.
For a particular interface ("System" in the pictures , Item in the FMEA),you may have a group of functions that are to be performed .These ideal functions are prompted by an input signal. In an FMEA the Input signal defines "Function". The "Ideal Function Output" is the function broken down into its constituent parts.
The anti-Function is the failure mode.
The "Error States" in the P-Diagram can either allude to the Failure Effect in the FMEA or causes/mechanisms.
The "Control Factors and Noise Factors" further define specific items to look at in defining failure causes/mechanisms.
See attached brief example (does not include everything provided on earlier attachment).
The benefit for me of using the P-Diagram,lies in the fact that it causes me to think before I act in filling out an FMEA. I use it specifically to help me develop System and Component DFMEA's. It could probably be used on PFMEA's,but I have not had an opportunity yet.
The FMEA has had a bad rep over the years because some people approach it and blindly fill it out ,offtimes leaving out important info. Because of this,we have product recalls or loss of business.
To me the P-Diagram in conjunction with the Design Functional Block (or Process Map) forces further discipline into the FMEA process.