Difference between cpkppk
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June 2, 2007 at 12:03 pm #47148
JIJU JOSEPHParticipant@JIJU-JOSEPHInclude @JIJU-JOSEPH in your post and this person will
be notified via email.As per the def. in this site ppk is long term process capability & cpk is short term capability. But in the second edition of SPC( AIAG Manual) cpk is the limit of natural variation and ppk is total variation(cpk+special cuase variation). Anybody canclear my doubt?
0June 2, 2007 at 1:45 pm #156855Both definition are same. Actually, short term capability of a process is due to natural variation or common cause variation whereas Long term capability includes both common cause and special cause variation.
0June 2, 2007 at 2:36 pm #156856
Fake Gary AlertParticipant@Fake-Gary-AlertInclude @Fake-Gary-Alert in your post and this person will
be notified via email.Cp & Cpk are used for short-term capability and Pp,Ppk are used for long-term capability.
0June 2, 2007 at 5:46 pm #156859Cp = Process Capability.
Cpk = Process Capability Index. Adjust for Non-Centered Distribution
Pp = Process Performance.
Ppk = Process Performance Index. Adjust for Non-Centered Distribution
Ppk produces an index number (like 1.33) for the process variation. Cpk references the variation to your specification limits. If you want to know how much variation is in a process, use a Ppk measurement. If you want to know how that variation will affect the ability of your process to meet customer requirements, you should use Cpk.
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