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AIAG FMEA PFMEA Severity Scoring

Discussion in 'FMEA - Failure Modes and Effects Analysis' started by Englishman Abroad, Jun 20, 2016.

  1. Englishman Abroad

    Englishman Abroad Member

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    All,

    I am a little confused, in the AIAG Process FMEA severity ranking table, why do the criteria include comments regarding the occurence of the failure; e.g. 7 = "...Or a portion of the production run (less than 100%) scrapped..."

    e.g. 5 = "...Or a portion of product may have to be reworked, or repaired off-line."


    I would have thought this would be better handled in the Occurence rating. (Or is it trying to communicate that a percentage of the next level assembly, (sub assembly or vehicle) may be scrapped.)

    Thanks for you feedback.
     
  2. Golfman25

    Golfman25 Well-Known Member

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    To me it indicates whether the issues is a total failure of the part or that it can be "fixed" after the fact.
     
  3. ncwalker

    ncwalker Well-Known Member

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    Methinks you are looking at the wrong table or the wrong revision. I am looking at 4th Edition. My number 7 in the severity table is "High - Vehicle/item operable but at a reduced level of performance. Customer very dissatisfied."
     
  4. ncwalker

    ncwalker Well-Known Member

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    Methinks I did not read the question carefully and I quoted you the DFMEA severity. You asked about the PFMEA severity.

    The reason they talk occurrences is because the severity to a process is how it affects the process. "Customer very dissatisfied" does not really apply well when talking about a process. Who is the customer? The plant manager? So they took the original ranking, because the DFMEA as the first thing they did, and said "How can we translate this to a process?"

    Severity in the PFMEA sense is how it affects the process and not the part the process produces. In this case, a severity of 7 (high) means if the item in question goes out of control, it will result in the process producing significant rework that takes a significant amount of time to perform.
     
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  5. Englishman Abroad

    Englishman Abroad Member

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    NC,

    Thanks - I think I understand; The major differences are on the inconveinience to the manufacturing process;

    To compare the ratings 7 = Scrapped, 6 = reworked off line, 5 = reworked off line, 4= rework in station, 3 = rework in station.

    I still think that they should not have put the percentages in the severity rating as this mixes occurence and severity.

    Thanks
     
  6. ncwalker

    ncwalker Well-Known Member

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    They shouldn't do a lot of things. ;-) All the AIAG stuff is done by committee. Because of this, there is a "one size fits most" sort of sense to it. The problem with that is we are ALSO all supposed to be JIT and zero defect. By nature, this means that YOU need to tailor your operation for what works best at YOUR location. Because if you copy what I do, it won't work as well as if you. In fact, if you are in a large organization with several sites, even site to site the same thing doesn't always work.

    What we need to be doing is meeting the intent of what AIAG says tailored to be efficient in our own facilities. Once the auditors get involved, however, it frequently turns into an exercise of matching exactly what AIAG says because that is easier on them to demonstrate compliance. There are some stellar auditors and SQs out there who "get it." And totally understand if you make an adjustment because it is better suited to your facility with obvious benefits. And there are those who say "that doesn't look like the example in the blue books."

    Don't get me started on Process Flow Diagrams....

    And good luck on Thrusday with the vote.
     
  7. Golfman25

    Golfman25 Well-Known Member

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    Excellent post. Even the AIAG books talk about guidelines and recommendations. Unfortunately, these days if it doesn't match exactly you're in a world of hurt. Went down that road with our last auditor. Absolutely ridiculous.

    The thing is, building a car is a complex endeavor. So these processes and forms may make sense to them. It makes less sense to a job shop just trying to make a part or two. These requirements need adjustability.
     
  8. ncwalker

    ncwalker Well-Known Member

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    You are right in that building a car is a complex endeavor. However, that does not mean we should willy-nilly push all the complexity onto the individual components. I'm in the tier 1 world, so my components I sell are, in fact, complex. But that's not the case in MY supply base. My bolt manufacturer does not need a control plan for every bolt he makes. I'd rather he have a good system on making bolts, whatever the size, that is structured in such a way that when he has an issue, he leverages it onto ALL his parts seamlessly. So his control plan isn't up to par with all t's and i's.... so what. I'll take the less than perfect by the book control plan in exchange for him having a real good handle on his capacity any day. I'll take a canned PFMEA if I know he understands how to do Gage R&Rs. You go down into the tiers and a lot of places do not have the staff to support everything. In my supply base, a guys first PPAP usually sucks and wouldn't pass muster - we still go into production because we do the legwork to make sure the PARTS are OK. Next PPAP is better, and the next better. We keep gentle, guiding pressure on them. After they launch about 5 parts, I honestly don't have to check their PPAPs anymore. They have it. In my organization they look at me and tell me I spend too much time training them and that "these suppliers" are all automotive suppliers and they should "know all this stuff already." I agree that statement should be true, but that doesn't mean it is. So what? We only deal with suppliers who are experts in this? Good luck finding them for the niche parts ....

    (I need to get a seat on the AIAG. :-( )
     

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