We often perform capability studies for our customers on dimensions, but now we are faced with a dilema. One of our customers is asking for a capability study on a measurement that is defined as a range on the print. The print says that any measurement between .33 & .80 is good, without defining a target. We have completed the Gage R&R and the XBAR, R charts succesfully. The problem is we don't know how to do a capability study when there is no set target value. Is this possible.

Sorry Marc, but I have been away for awhile, for reasons you know. My on-line time has also been reduced, but I will still try to help with some topics when I can. Will be back as soon as I can. Anyway, on with the show.

As far as capability goes, I would suggest precabcorp download and read the cpk.pdf paper I have written and posted. You can find it at Marc's pdf zone.

Remember that Cpk or Ppk only cares about how close you are to one tolerance end or the other, not how close you are to the target - that's Cpm. Your tolerance is .33 and .80. What's your capability?