PFMEA Severity Ranking - 9 is with warning and a 10 is without warning

General Question - for ranking severity, the only difference between a 9 and a 10 is, a 9 is with warning and a 10 is without warning. Does warning include operator notification that the process he/she is performing may be "hazardous" or, does the process have to signal some type of warning that a failure is about to occurr, say a flashing light or horn sounding. Also, does process failure warning include a part that fails in steps? For example, an operator pressurizes a pipe, and the pipe starts to hiss (which warns the operator) before it explodes, versus, the pipe is pressurized and then explodes without any warning (no hissing)? Any clarification on this issue is greatly appreciated.

Mike,

You have valid questions but the value of the ratings are very subjective. There is no right or wrong ranking system, the supplier defines what the ranking system is based on the specific product or process.

The tables in the AIAG FMEA manual are only "suggested" evaluation criteria.

Hope this helps a bit.

ASD...

[Marc]

Is anyone aware of any 'standard' or guideline(s) on PFMEAs with respect to operator notification in cases of potential exposure to hazards? I've worked in several 'hazardous' industries and I don't remember ever seeing any links. I think that's addressed by the safety aspect (including givernmental regulations), yes?

[bpritts]

Marc,

The most recent (3d edition) automotive FMEA manual parallels the end user's
situation (failure without warning = 10, failure with warning = 9); they
also give a 10 if a component/material endangers a downstream manufacturing
process/operator (without warning = 10, with warning = 9).
P 43 of DX/Ford/GM manual). No real elaboration, though.

I would have to agree with the earlier comment in the thread, though ---
I don't anguish over 1 point differences in the inputs for occurrence, severity,
and detection figures. It's more important to anguish over how to achieve
improvements.

Regards,

Brad

[Bill Ryan]

Originally Posted by bpritts

I would have to agree with the earlier comment in the thread, though ---
I don't anguish over 1 point differences in the inputs for occurrence, severity,
and detection figures. It's more important to anguish over how to achieve
improvements.

Agreed!!!! I've seen much to much time wasted arguing whether it should be a 9 or 10 - or 5 or 6. Some customers have even come out with their own improved (??) rating tables - which haven't clarified much of anything.

One of the only things I harp at our teams about is to be consistent - no matter the rating value.

Bill

[howste]

I haven't seen anything in writing to clarify this. To me though, if I'm walking through a mine field it's a 10 regardless of whether posted warning signs exist.