Low00Ranger
Registered
I should start by saying I have very little experience with Six Sigma. This forum has helped me greatly in recent weeks. Thank you all for that.
Onto the root of my issue... I have an engineering manager asking for Cpk data for injection molding processes. At first I thought he wanted samples run and measured to validate our current processes. I was wrong.
He's asking for continuous Cpk data as way to validate individual process parameters; cushion, fill time, recovery, etc... I already track those. So, applying the formulas is simple enough. The issue is the calculated Cpk is insanely high. As an example, my fill time spec is 3.00 +/-0.25, mean is 2.95, standard deviation is 0.002. Cpk calculates out to 66.667.
Is Cpk even applicable to in this situation? Is there a better SPC that I should be using. I've always just done basic trend monitoring, to show the repeatability of a process. Any time I've been involved with was pre-production; run a series of samples, measure critical dimensions, and calculate the reliability of the process. This just has me confused.
Onto the root of my issue... I have an engineering manager asking for Cpk data for injection molding processes. At first I thought he wanted samples run and measured to validate our current processes. I was wrong.
He's asking for continuous Cpk data as way to validate individual process parameters; cushion, fill time, recovery, etc... I already track those. So, applying the formulas is simple enough. The issue is the calculated Cpk is insanely high. As an example, my fill time spec is 3.00 +/-0.25, mean is 2.95, standard deviation is 0.002. Cpk calculates out to 66.667.
Is Cpk even applicable to in this situation? Is there a better SPC that I should be using. I've always just done basic trend monitoring, to show the repeatability of a process. Any time I've been involved with was pre-production; run a series of samples, measure critical dimensions, and calculate the reliability of the process. This just has me confused.
