A
Atul Khandekar
komlossy said:....
This is clear to me. But what if we have no tolerance range, because there is only one tolerance limit? Maybe I go and check the SPC topics, they should face the same problem when calculating CPK...
I've seen two views about this. One says that %Tolerance cannot be defined in case of single-sided tolerance (like Cp) and that you should compare GRR with Process variation that you get from ongoing SPC syudies.
The other view is that you can calculate the value of tolerance from process mean to the available specification and use the constant 3 instead of 6 (or 2.575 if you are using the 'traditional' 5.15 to represent the full spread of error)
Comments anyone?