On The Money
Two different processes.
- Initial process capability study; 100/125 pc sample size, run parts with no adjustments to set-up, measure oarts, plot on chart, evaluate, make adjustments and re-run study.
- on-going process control; evaluate charts periodically, make changes when process shows evidence of gion out of control.
Sam is right on the money. Are you being required for on-going SPC for the characteristic you've been discussing. On a CNC shooting for nominal is not a biggy. If you have tool compensation running you should be ok for the future SPC requirements, provided you have any.
We are a metal stamper. I continually have customers wanting Cpk numbers for holes and slots. In metal stamping punches (to put in the hole or slot) are always ground to the high side of the tolerance for wearability purposes, thus your Cpk numbers will always suck. I have done pretty well at convnincing most customeras to look at the Cp numbers and not the Cpk number.
Oh well......and they ask me why I drink!
:thedeal: