iSixSigma

67 ppm

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  • #37428

    Leon
    Participant

    Dear all,
    I am a Quality executive!My company activities are stamping and sub-assembly metal parts for automotive industry!We have started Six Sigma project half year ago!My GM always said 67ppm is equal to sigma level six, how can i relate this two metrics?
    Thank you!
    Leon
     

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    #110171

    Mike Carnell
    Participant

    Leon,
    Look up 6 sigma – it is parts per billion. As him where he got the 67. See what he says. Maybe he has a method of getting there.
    Good luck

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    #110172

    Mikel
    Member

    The first metric is your GM does not know what he is talking about.
    The other thing that might be happening is if you buy into the 1.5 shift nonsense, some people think you count both tails of the distribution which would be 6.8 DPMO.
    What it should be:
    If you buy into the 1.5 shift – 6 sigma is 3.4 DPMO
    If you don’t – 6 sigma is 2 DPBO (that’s two defects per billion)

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    #110173

    Johnny Guilherme
    Participant

    Stan
    Can you help. I have never really understood why the six sigma. Does this mean 3 sigma to the left of the target anf 3 to the right equalling 6. You mentioned 1.5 sigma which then equates to 3 sigmain total. Why then is it called 6 sigma. Also how does one arrive at the 3.4 dpm once the six sigma is achieved.
    many thanks
    Johnny

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    #110175

    Mikel
    Member

    It is six to the left and six to the right. The movement of the entire distribution to the left or right will leave only 4.5 on the side that moved toward a limit. Look up a z value of -4.5 in normsdist in Excel and it will return the famed 3.4 DPMO.
    The 1.5? It was an observation of a good process engineer back in 1984 or 85. Many, many have tried to bring proof since then, most notably Dr. Mikel Harry, but its all nonsense. Processes move and processes also can get wider over time, but with a great understanding of the process and rational controls to detect changes at the source will prevent anything even close to 1.5. I have, and I know Mike Carnell has, always been able to do better. The self appointed pundit for the proof of the shift on this forum has also admited to have never done a six sigma implementation. You decide who to believe.

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    #110189

    Dog Sxxt
    Participant

    The boss is always right!

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