Cpu & Cpk can be calculated the same?

O

Omeil

#1
I have been wondering about the calculation of CPK and CPU, can they be calculated the same?

CPU=(USL-Mean)/(3*Stdv)

Can CPK be calculated the same we thus having CPK = CPU, its just a something i heard around my workplace which confused me.

Thanks for your clarification

Omeil
 
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reynald

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#2
I have been wondering about the calculation of CPK and CPU, can they be calculated the same?

CPU=(USL-Mean)/(3*Stdv)

Can CPK be calculated the same we thus having CPK = CPU, its just a something i heard around my workplace which confused me.

Thanks for your clarification

Omeil
Cpk is defined as the mininum between
{CPU=(USL-Mean)/(3*Stdv)
and
CPL=(Mean-LSL)/(3*Stdv)}
where sigma is defined as the sigma within subgroups.

So to answer you question, yes it can be calculated by the same formula given that your process is shifted to the USL side. If it is otherwise shited on the LSL side, you may use CPL=(Mean-LSL)/(3*Stdv). That is basically what in means by the taking the minimum between the Cpu and Cpl.

Hope it clears your confusion.
Regards,
Reynald
 
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