J
johnny xu
Suppose we get the result of % GR&R=11.8% when conducting MSA, and then calculate PPK=1.67.
Who tell me actual PPK value is above or below 1.67 ? and why?
THX
Who tell me actual PPK value is above or below 1.67 ? and why?
THX
Need help calculating actual Ppk - Result of % GR&R=11.8% when conducting MSA
The relationship is between the variances (s^2) and is shown by this equation:
S^2 (observed) = S^2 (actual) + S^2 (measurement)
This may be restated as:
S^2 (actual) = S^2 (observed) - S^2 (measurement)
Take S^2 (observed) from the capability study and S^2 (measurement) from the MSA to calculate S^2 (actual). Use this to calculate the actual Cpk/Ppk.
Note: if reporting this to a customer, be truthful about what you did.
S^2 (observed) = S^2 (actual) + S^2 (measurement)
This may be restated as:
S^2 (actual) = S^2 (observed) - S^2 (measurement)
Take S^2 (observed) from the capability study and S^2 (measurement) from the MSA to calculate S^2 (actual). Use this to calculate the actual Cpk/Ppk.
Note: if reporting this to a customer, be truthful about what you did.
J
johnny xu
Firstly I’d thanks for your help.
But I have two part question.
a. Regarding formulate you provided , which book illustrate it? AIAG MSA? Or others?
b. Take my question for example , as you mean, PPK calculated value 1.67( observed value) ----is right? If wrong, can you give me a detailed example or figure to explain this formulate---which is value observed ? value measured?
Thanks a million
But I have two part question.
a. Regarding formulate you provided , which book illustrate it? AIAG MSA? Or others?
b. Take my question for example , as you mean, PPK calculated value 1.67( observed value) ----is right? If wrong, can you give me a detailed example or figure to explain this formulate---which is value observed ? value measured?
Thanks a million
I do not have my copy of the MSA manual at hand, but I believe that the formula may be found in it. I know it may be found on page 5 of Dr. Wheeler's An Honest Gauge R&R Study.
The true Ppk will be greater than 1.67. The MSA manual has a chart that shows the effect of measurement variation on capability. Or you can use the equation that I provided and calculate it directly.
The true Ppk will be greater than 1.67. The MSA manual has a chart that shows the effect of measurement variation on capability. Or you can use the equation that I provided and calculate it directly.
Rameshwar25
Quite Involved in Discussions
The explanation is given in MSA IVth Ed (Pg 199-202).
regards
rameshwar
regards
rameshwar
J
johnny xu
Hi miner,
Thanks for attachment you provided , I read it carefully on page of 5 , but didn’t find it.
Thanks for attachment you provided , I read it carefully on page of 5 , but didn’t find it.
J
johnny xu
Last edited by a moderator:
Rameshwar25
Quite Involved in Discussions
it's here.
One thing to remember is that the formula is a mathematical truth and doesn't require the 'validation' that a 'standard' may confer. It can be proven with very simple mathematics. Just because something is published in a 'standard' doesn't mean it's true or even valuable.
J
johnny xu
Who can make any conclusion? THX
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