Capability Study for Tapped Hole

I have a PPAP I'm working to get approval on. The part has a HIC on an M6 tapped hole. They are requesting a Capability study on the Tapped hole. I'm not really sure how to do this. Any suggestions? We ran a 300 pc run with no rejections for the tap.


Stop X-bar/R Madness!!
I would provide an attribute capability study.....which you already have the results for. (Minitab: binomial % defective)

Bev D

Heretical Statistician
Staff member
Super Moderator
You can use the exact binomial or exact poisson to calculate the upper confidence limit for zero defects... the standard formulas are use the Normal approximation and require that you have a moderate defect rate to be useful - or even to complete the calculation. I am away from work right now so I don’t have the formula at my finger tips. But there is an excel approach to calculating this - a simple google search should find it.

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