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Capability Index.

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  • #52903

    S
    Participant

    Why Cp=1 when specification spread is taken as 6s  which is equivalant to 0.27 % out of spec. Is it not wise to take 5.15 s as this is equivalent to 1 %? Generally for R&R measurement it is equivalant to 5.15.      This will definately more logical and ease out situation.
    Regards
    Pradeep Joshi

    0
    #186719

    Mikel
    Member

    Why not 3.290? 5% is definitely easier and god knows we just want something easier.BTW 5.15 has not been used for GR&R for over a decade.

    0
    #186720

    Ang
    Participant

    just taking a guess from not really knowing =)
    Capability Index 1 (3/3) were found to be at the time (1930 something) a good process and +/- 3 StDve were stated as sort of norm en lived ever since.
    Probably if the index were to be “invented” today it would be 6/6=1?
     

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    #186721

    Mikel
    Member

    Actually goes back only to the 60’s.It has been fairly well demonstrated that if Cpm can be maintained >
    1.33, it’s all you need.

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