Regarding Cgk I have some info. But I am not really sure if its right.
5.4.3 The Gauge Capability (cgk):
The gauge capability study is applicable when measurements taken are not influenced by the operator. This is where measurements are taken / read by the measuring unit which is integrated in the machine. Also this method could be applicable when the measurement can not be repeated twice on one sample (destructive measurements).
A principle of this study is to measure the same feature at least 50 times using the measuring unit. The acceptable capability index of this study is cgk ≥ 1.33 unless otherwise specified by the customer or by any other means.
For calculating the capability values, the following can be used.
• Calculation sheet of GME Document ххххххх, Machine Capability Analysis • Mintab Software or any other appropriate software.
5.4.3.1 Evaluation criteria for Gauge Capability:
• cgk≥1.33 - the measurement method is acceptable • cgk<1.33 - the measurement system is not sufficient for measurement. The real process capability can be jeopardized by wrong measurement system. A deep analysis must be done in order to define and eliminate the root cause of the variability.
(Wrong measuring tool, accuracy, maintenance).
• After the root causes are defined and solved, the MSA study must be repeated again.