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FMEA/Sigma Level

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Viewing 9 posts - 1 through 9 (of 9 total)
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  • May 18, 2002 at 4:48 pm #29473

    Robson
    ★ 20 Years ★
    Member

    Hello people!
    Have you ever used the FMEA (occurency classification) to calculate sigma level? I’d like to compare my Potential Risk and Sigma Level……

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    May 19, 2002 at 4:42 am #75584

    Mike Carnell
    ★ 20 Years ★
    Participant

    Robson,
    At the risk of pissing you off I think you have this backwards. The selection of the value fot the Occurance value should be derived from some data. If you do a capability study and establish the PPM level you will have data to select the value using the scale in the AIAG manual.
    If you do the FMEA first where do you get the ppm level?

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    May 20, 2002 at 2:00 am #75592

    Jay Fleischmann
    ★ 20 Years ★
    Participant

    To actually give you an answer, yeah, I think you could calculate sigma level from occurence.  I’ve never seen or heard of it being done that way though. 
    Most companies, unless your a startup outfit, develop no interest in sigma level until they become educated in Six Sigma.  Six Sigma, as you all know, uses sigma level as a basis for establishing a reference point.  Then, company A suddenly has an interest in this index.  They take a quick glance at their FMEA and Blammo, get an estimated sigma level.
     

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    May 20, 2002 at 11:27 am #75597

    Robson
    ★ 20 Years ★
    Member

    Mike, in fact, I began the FMEA study, but didn’t finish yet. Afterwards, we are going to compare the original ocurrence value with the new occurence. It must be less than the original, so the original sigma level will be different too.
    Jay, thank you.

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    May 20, 2002 at 3:35 pm #75605

    RR Kunes
    ★ 20 Years ★
    Member

    I sounds as if you are misusing two tools. 1) FMEA 2) Sigma calculation.
     
    Best go back to ground zero and start over.
     

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    May 20, 2002 at 3:38 pm #75607

    RR Kunes
    ★ 20 Years ★
    Member

    Sigma calculaton is based on defect per million opportunities. However, this is based on a process, not on a symptom of a defect.
    If you have data on the frequency of occurrence of a specific defect or failure mode that is what you use to calculate or estimate occurrence.
    DO NOT CONFUSE THIS WITH A SIGMA CALCULATION!!!!!

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    May 21, 2002 at 12:09 pm #75626

    Edwards
    ★ 10 Years ★
    Participant

    Six Sigma is all about change (fast).  Why anyone would want to spend days conducting a precess FMEA is beyond me.  There are better and much faster tools available…brainstorming, NGT & C&E Matrix.  These 3 tools can all be used in a 2 hour team session, gets straight to a basis for an action plan…time to move on? I use this in every 6s project that I conduct, works for me every time.
    David

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    May 21, 2002 at 12:47 pm #75627

    Robson
    ★ 20 Years ★
    Member

    Hello David, thank you!
    I’m conducting a Super-FMEA to many utilities equipments (compressors, subestations, dries, chillers, etc.) and I ‘d like to do a kind of link between FMEA and Sigma Level, but you have reason: there are many faster tools to do this.

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    May 21, 2002 at 2:12 pm #75630

    TCJ
    ★ 20 Years ★
    Member

    As David mentioned there are faster ways to understand some of the root causes of your problem (NGT, C&E Matrix), but they fail to weigh the risk and document improvement actions.  I suggest you continue with the FMEA because you will amass more information about your process.   I’m not sure why you want to calculate the sigma value of individual failure modes.  Calculate the Sigma value of the response variable that you want to impact with your FMEA (throughtput, downtime, safety, quality, etc.) it should be robust enough to encompass the individual failure modes.

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