Re: Major change of FMEA 4th Edition???
A couple quick notes on the 4th Edition-
RPN levels- They don't want a 'set rpn level' to drive improvement [ex.: everything over 100 rpn requires improvement]. But RPN still matters. RPN = Sev X Occ x Det. They've also stated to try to use other methods to drive improvement. Other methods are Sev x Occ, or Sev x Det. Some automotives already have "rpn" levels for these SO-SD ratings in their specific requirements.
Occurrence ratings- In light of this AIAG 'bumped up' all the occurrence requirements at least one level: 7 to 10 is still the same; but, 1 to 6 is changed. Before #6 Occ was 5pcs. in 1000; now, in the 4thEd. it is 2pcs. in 1000 (this is a change from 5000ppm to 2000ppm). This rate killing continues through the rest of the levels to #1, where failure is eliminated, not even 1ppm. I don't think they want 1's to mean anything.
Aside- In every new edition of the fmea manual they have altered the ratings tables, supposedly for clarity??? The 4th Edition is no exception. Ratings continue to be re-defined so they are harder to meet. We'll spend months re-defining our ratings and figuring out how to update our 200+ older version active fmea's to meet the living document clause.
DFMEA linkage- 4th Ed. Linkage to the dfmea may mean that severity from the dfmea has to carry over to that item on the
pfmea. We've seen too many customer dfmea's where every single item had severity of 7 or 8; now, we'll have to carry their severity over to the pfmea even though the rating is way out of line. Customer SQE's and SRE's will have a field day auditing the 4th Edition fmea's.
enjoy. AIAG has to stay in business....