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How to accurately evaluate "OCC" ranking ?

Discussion in 'FMEA - Failure Modes and Effects Analysis' started by Pongsakorn, Mar 22, 2023.

  1. Pongsakorn

    Pongsakorn Active Member

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    With reference to AIAG FMEA Manual 4th edition, the OCC ranking will be based on "Occurrence of cause" not "Occurrence of Failure". Therefore, each potential cause of failure will have different OCC ranking.
    However, I believe that most of manufacturing company only track the % or ppm of each failure mode but does not track the % or ppm of failure mode by each cause. As such, there is no data that can be used to evaluate OCC ranking accurately.
    Please advise what should be the proper way to evaluate OCC ranking without such data.

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    Pongsakorn, Mar 22, 2023
    #1
  2. Andy Nichols

    Andy Nichols Moderator Staff Member

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    As with all ratings for FMEA, the organization should derive their own data. As they say, the FMEA is "a living document". Draw a line in the sand and begin to compile your own data on occurrences.
     
    Andy Nichols, Mar 22, 2023
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  3. Pongsakorn

    Pongsakorn Active Member

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    Andy, thanks.
    I am not sure if it is usual to track the occurrence of failure by each cause of failure. I guess that most of organization just "estimate" the occurrence of cause not from the actual data.
    What do you think?
     
    Pongsakorn, Mar 23, 2023
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  4. Andy Nichols

    Andy Nichols Moderator Staff Member

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    It’s true, what you say, since the book is a “purest” viewpoint, so as long as your data is accurate, why not? The FMEA can always be improved. I’d say that doing it, putting in place the control plan etc will still give benefit. Please be sure to get the first few columns accurate and the rest will be fine!
     
    Andy Nichols, Mar 23, 2023
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  5. Pongsakorn

    Pongsakorn Active Member

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    Really thanks for the comment, Andy.
     
    Pongsakorn, Mar 26, 2023
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