DFMEA/PFMEA mitigation of high severity (9-10) in low volume products

[Rahmberg]

Hi

From time to time I encounter having very high severity ratings in both DFMEA and PFMEA (9-10), which of course needs to be mitigated as much as entirely possible, but how to determine when enough is enough in a low volume business where safety is of absolute highest focus.

According to our internal special characteristic procedure, mitigation and Special characteristic classification is required sev.>8 and occurrence > 1 (completely error-proofed), so whatever we do, it will never be enough if the risk cannot be entirely removed.

How do any of you handle this ?
For these high severity risks, do you distinguish between how to mitigated based on occurrence (e.g. occ.=2 --> communicate risk, occ.>3 --> design/process change) ?

Thanks.

 

[Bev D]

I deal with high severity risk all of the time. The key point here is that occurence cannot be a guess - you must know what hate occurence is by testing your mitigation’s and controls. This is the entire point of FMEA - to drive action and knowledge. You test the system to know what characteristics are critical and what the tolerances need to be to guarantee a result that meets requirements. You add controls to both inputs and outputs to ensure those tolerances are met. You add error proofing and inspections - and perform the MSAs necessary to understand the effectiveness of these controls. Then you KNOW how low your occurence is.