Process Capability - How much percentage of tolerance?

[JAI GANESH]

In a automotive manufacturing process, to achieve 1.67 Cp, how much percentage of tolerance i must have to use. Can any one help me out??

 

[KnoKsuKaO]

Re: Process Capability

Hello,
it's approx. 99,73%

 

[Bev D]

It's 60%. The inverse of the index gives the proportion of the tolerance 'consumed' by the process. If you look at the formula you will see that it is a measure of the tolerance divided by a measure of the process spread. So 1/1.67 = .6. Which is 60%

But remember the Xpk indices include the SD of the process AND the location of the process average in relation to the tolerances.

 

[Golfman25]

Basically what be said. You can set your working limits at 60%. But it could be better or worse depending on your SD.