Re: What is Cgk? (Index of Testing Means Capability)
There is not much information available on this topic, which means that it never really took off.
The short story is:
Cg = 0.2 * StDev(Process) / StDev(Gage)
Cgk = [3 * StDev(Process) - |Bias|] / [3 * StDev(Gage)]
Cg is really rendundant if you have %GRR. It adds no new information, just packages it differently. Cgk is only of use if you did not establish credible calibration acceptance limits. If that was done, Cgk adds little value.