As a subject matter expert in statistical process control and quality management, I can provide a detailed explanation regarding the relationship between CPK and CP.

CPK, which stands for Process Capability Index, is a measure of how capable a manufacturing process is of producing output within specified limits. It takes into account both the process's ability to stay within the specification limits (Cp) and the centring of the process distribution relative to the target value (Cpk).

CP, or Process Capability (Cp), is a component of CPK and measures the process variability relative to the specification limits. It does not consider the location of the process mean.

Now, regarding the question of whether the value of CPK can exceed the value of CP: Theoretically, it is not possible for CPK to be greater than CP because CPK is always less than or equal to CP. This is because CPK includes an additional factor that accounts for the process's deviation from the target value, which can only reduce the overall index value when compared to CP.

To clarify with an example: If a process has a Cp value of 1.0, the CPK value can be at most 1.0, but it could be less if the process mean is not centered between the specification limits.

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Cpk is more widely used than Cp, since it takes into account the mean and the standard deviation in its calculation. ... When the average of the specification is equal to the target value, then Cpk is equal to Cp. Cpk can never exceed Cp.read more >>