PPK value extremely high

[#1]

Hi everyone,

I have a process that has a very high Ppk (> 4 ) - can this value be considered correct and what's its interpretation? or doesn't make any sense and there might be an issue with my data/calculations?

Thanks in advance.

[#2]

Assuming the measurements are valid, I would interpret this as specs potentially being too loose.

[#3]

If you have check the data & distribution are all valid data;

- The centering & spread is far from spec limits.

Especially for some electrical tests, I've seen Ppk > 6.

Spec limit is based on 3F (Form, Fit & Function). So, the process is good & I will put more focus on lower Ppk process.

[#4]

Count your blessings and move on...

[#5]

Impossible to give advice as you haven't described the situation well enough.  How did you collect samples used to estimate the descriptive statistics? How representative are your samples?  Over what changing conditions (what is the inference space)?  Have you investigated the measurement systems?  If your measurement system has poor discrimination, then you can under estimate the variation.  Do you have an evidence the process is stable?

A disclaimer, I am not a fan of capability indices.  There are multiple statistics estimated via sampling, therefore there are confidence intervals around each statistic (and, of course, you are reporting one number...there must at least be an interval) and then you have specifications that are independently derived and potentially pulled from thin air...