FMEA Question

This topic contains 6 replies, has 5 voices, and was last updated by  James Heidt 9 months ago.

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    Karpagam Manivannan

    Interview question:
    We all know Severity, occurrence and detection are the key to identify the risk while designing or establishing a process. If given a chance to work and modify only one among severity, occurrence or detection to reduce RPN, what that would be and why?


    Chris Seider

    homework question?

    Basically many of us know severity doesn’t change with changes in the process unless the defect itself changes….for example, too high of pH material would hurt someone was the old severity and unless something like buffering of solution or something would prevent the defect from being such high pH (then the defect would need to be reworded or added as another one)–then the severity could change.


    Karpagam Manivannan

    Well, this is just a failytale question asked to me. I answered as detection thinking that detecting the failure would enable us to work on severity or occurrence but now rethinking and curious to know what could have been the right answer.



    I’d agree that you should choose detection with the caveat that if the probability of detecting the defect is high it’s of little concern. Severity, as @cseider noted, is not influenced by the other two. You can’t be confident about occurrence without detection.



    There is no question here ! Severity is defined as a defect which would result in human injury or death. (Read the literature) Since all three categories are multiplicative addressing any of the three will reduce your RPN value however defining the defect that will result in human injury and eliminating it will always be the correct choice.
    As an example is if stepping on the brakes stops your vehicle and prevent injury even if you have a light which alerts you to the brake system failure wont help you if it lights up while driving down a steep grade in a 18 wheeler fully loaded. Therefore showing detection is not the solution. Also having a backup system like and emergency brake will help you only in certain circumstances this also would not be your preference. In this case a redundant backup system would be the correct solution.
    So Eliminating the potential defect reducing or eliminating t he severity is the correct approach.


    James F Giguere

    I’d choose Occurrence. Taking an electric appliance as an example… you cannot reduce the severity of a shock from a 110 volt outlet, but with an unlimited budget you can use double wall construction and other design ideas to reduce the occurrence so low that you don’t even need the end-of-line hipot test to detect. This is why there is a push for doing Hazard analysis, where you can take into account both the probability that the hazard will occur and the probability that the occurrence will lead to harm.


    James Heidt

    This also seems like a homework question to me. My first thought was detection, because if you can’t detect a problem (as Strayer says) you can’t be sure of the occurrence. Maybe you could do an FMEA to decide which is a bigger risk – detection or occurrence.

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