>1 there are subgroups and the Cp and Cpk are calculated with the estimated STDEV within. ![]() With a higher Cpk value the data set is better within tolerance.Ġ is no subgroups the overall STDEV will be used and the Pp and Ppk will be calculated.ġ is no subgroups the STDEV within will be estimated and the Cp and Cpk will be calculated. ![]() Violet the process is probably not in control the difference between Cpk and Ppk is bigger as 15%. Therefore the Cp is always lower of equal compared to the Cpk value. To get this quality (Cpk) the process needs to be tuned so that mean is moved to center of the tolerance borders. The Cp does not include the drift between the subgroups! If you want to included the drift use the Pp. The Cp indicates if a process is capable to produce within the specification limits, if the process is centered between the specification limits. For not production environment (testing, new process or setting) use the Pp and Ppk! The Cp and Cpk is used when a process is under statistical control. When this value is 0 the Pp and Ppk are calculated. The Cp and Cpk is calculated when the subgroup is set 1 or higher. The Cp Cpk Pp and Ppk are used together with Control charts in Statistical process control (SPC) ![]() To check if the production process is capable to produce within specification limits. ![]() Full version of DevelveFor commercial use 75 EURO
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