Does the Detection rating have anything to do with Prevention?

[Andrews]

If a particular problem of oversize is caused by tool becoming blunt and if periodic tool resharpening is the current prevention control for this particular cause and hourly monitoring is the current detection control for detecting the failure then what is the rating we should give for occurence?Doess the detection rating have anything to do with prevention?

[Marc]

If detection is likely, your RPN will drop. Since you pretty well have it pegged to tool wear and are predicting the tool wear, I would expect a low RPN for that line item.

I can't give you an exact number for detection, but I would expect it to be low - 1 or 2 if it's that obvious.

Since it's going to happen, occurance rating would be high - say 9 or 10. The key will be your severity rating and your control.

[Obi-Wan]

If oversize (the Failure Mode) is caused by tool wear and periodic tool resharpening is the current
prevention control for the particular cause, then hourly monitoring is the current detection control for the cause. There may be also be controls in place which detect the failure mode (oversize hole). You asked, "what is the rating we should give for occurence?" Base Occurrence on production volumme between tooling checks coupled with how good the checks really are. (I'd wager it is not a 1.)You also asked "Does the detection rating have anything to do with prevention? No, it does not. Prevention controls reduce Occurrence.

Occurance, prevention, and detection have no direct bearing on each other when "initiating" a FMEA.


During the process you might increase detection, big hairy deal, the part is already defective.

Prevention is the sole key in reducing occurance, but at what price??

Does the detection method offset the cost of the prevention method??

I would hazard a guess that prevention would win over detection in any process, therefore the FMEA.