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FMEA – RPN Threshold

Six Sigma – iSixSigma Forums General Forums Methodology FMEA – RPN Threshold

  • This topic has 5 replies, 3 voices, and was last updated 4 years ago by Rich B.
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  • #54174

    Hi all,

    I was having difficulty in calculating the Threshold RPN for a program. I am looking at the approach that I should be taking to do so. Is there any industry best practice / thumbrule that I can use…?

    Pls Assist.

    Thanks
    Bhargav

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    #194043

    Prabhu V
    Participant

    Hi Bhargav,

    As per FMEA guidelines based on the fourth edition, pls find the following regarding the RPN.

    i) Threshold values for RPN are not recommended.

    However,

    ii) Action can be taken prioritized based on Severity and RPN.

    iii) Severity ranking of 9 or 10 requires special attention irrespective of RPN.

    Hoping this will help you!!!

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    #200003

    Jasmine
    Participant

    I have tried ranking all risks as per their RPNs and then picking the top x% (usually 20%) as high risks. Not a bad approach if you’re looking for only a two-way categorization.

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    #201854

    Rich B
    Guest

    For a slightly different FMEA tool, google EFMEA (Expanded FMEA).
    Here’s a link to one version
    https://www.researchgate.net/publication/4067985_Expanded_FMEA_EFMEA

    Beat regards,

    RB

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    #201855

    Strayer
    Participant

    It’s about ranking, not thresholds. What are you going to do when RPN is below threshold, nothing? Also keep in mind that the item with the highest RPN might not be the one you should address first. If improvement is obvious, cheap, and quick why let it wait until after you’ve dealt with higher RPN’s?

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    #201857

    Rich B
    Guest

    Regarding thresholds & rankings, I commonly think of them as artificial targets that some folks pencil-whip into lower RPNs so they can game-the-system to ease their responsibilities. So a company’s rule of thumb to address any RPN > 150 (or whatever # will impress a customer) is a bogus bogey, because there are likely RPNs that have been “talked down” to somewhere under the rule-of-thumb target. As silly as that sounds, I’ve been literally ordered to reduce RPN values at two former employers… both of which are no longer open for business.
    I generally (from past experience) look into the top few RPNs, as in the Vital Few that are discernably elevated above the Trivial Many. The Scree Plot noted in the EFMEA is nice visual aid and I’ve used it as a communications tool so team members, managers and other viewers can get a sense of the ‘why’ behind the choice/s of higher RPNs being targeted.
    Quick/obvious and cheap improvements are Just-Do-Its that I’ll occasionally forward to an intern or engineering technician so they can get their hands into a problem. With the added instruction that if they have any problems, discuss with me so their efforts are heading in the best possible vector. When I was ‘coming-up’ it was big fun to let the intern and eventually engr tech learn the hard way… and I have two permanent injuries to show for callus jerks’ so-called training methods. (sorry, venting)

    Best to All,
    RB

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