Re: I have two doubts about PFMEA failure modes - How should I describe a "failure mo
Quote Bill Ryan
<snip> As I mentioned, this is how we tackle PFMEAs (that are submitted with PPAPs) at our company - there are others that list failures of the process as Failure Modes.
My "issue" with that methodology is that you can get into a "circle" where a Failure Cause turns into a Failure Mode or vice versa.
Bill, I believe your ‘circle issue’ is due to not separating different ‘levels’ of
FMEA’s (see attachment). If you have the same phrase repeating in different columns within the same FMEA,
then your thoughts are "bouncing around" and the team needs to clarify its FMEA scope.
With your Failure Cause of "Temperature setting - set too high", you may enter one of these loops based upon your Potential Controls description. Setting of the temperature is in another and separate Process Step and FMEA, such as “Machine XYZ’s control parameters.” The Failure Mode of this new FMEA line is "Temperature setting - set too high" from the original FMEA’s Cause. This separation provides for improved Failure Mode identification, such as “Temperature setting – out of calibration”, “Temperature setting – improper control response”, “Temperature setting – no control response”, and/or even “Temperature setting – intermittent control response”. This leads to the preventive / predictive maintenance program and recommendations to the calibration group of the plant.
[Note: Doesn’t the ‘New FMEA’ sound a lot like an equipment or machine FMEA?]
As to the your “Potential
Prevention Controls description” in the original (higher level) FMEA, you could enter something to the effect, “Setup of machine XYZ per standard work procedure A1234.” And for the Potential
Detection Controls description” something like “Record machine temperature on inspection form 3X2345 every 24 hours.”
Whether you document this lower level FMEA in the original FMEA or in a separate FMEA, just keep them separated (physically and mentally).
