Cpk Study on New Machine

Six Sigma – iSixSigma Forums General Forums Tools & Templates Cpk Study on New Machine

This topic contains 2 replies, has 3 voices, and was last updated by  Chuck White 1 year, 1 month ago.

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    Rory Schnacky

    Looking for input to do a Cpk study on a new bending machine just installed.
    My form is set up for a 30 to 90 pc study and will calculate the Cpk (looking for 1.67 or higher) and other information. This machine will be used to produce parts for O.E. customers.
    Thank you.


    Chris Seider

    I’d advise you to consider getting samples from each lane, cell, etc if you gather up to 90 samples so you can see if capability is impacted by these demographics.

    90 is a LOT but if sampling is easy and low cost to measure–just do it.


    Chuck White

    I agree with Chris — you want to capture as many of the possible variation sources as you can. For a snap shot capability study as you described, you should also use Pp/Ppk instead of Cp/Cpk. Cp and Cpk are only valid after you have established stability over time as evidenced by control charts.

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