Relationship Between Process Variability & Specification Width.
Three possible ranges for Cp:
Cp = 1, as in Fig. (a), process
variability just meets specifications.
Cp ≤ 1, as in Fig. (b), process not capable of producing within specifications.
Cp ≥ 1, as in Fig. (c), process
exceeds minimal specifications.
One shortcoming, Cp assumes that the process is centered on the specification range.
Cp=Cpk when process is centered.
Provide a numerical summary of the data being analyzed.
Factual information organized for analysis.
Numerical or other information represented in a form suitable for processing by
computer.
Values from scientific experiments.
Provide the basis for making inferences about the future.
Provide the foundation for assessing process capability.
Provide a common language to be used throughout an organization to describe a process
What is the process capability ratio CP?
Capability ratios (Cp/Pp) describe the variability of a process relative to the specification limits. A capability ratio is a unit-less value describing the ratio of process distribution spread to specification limits spread.
What is a good Cp process capability?
In general, the higher the Cpk, the better. A Cpk value less than 1.0 is considered poor and the process is not capable. A value between 1.0 and 1.33 is considered barely capable, and a value greater than 1.33 is considered capable. But, you should aim for a Cpk value of 2.00 or higher where possible.
How is Cp process capability calculated?
To calculate Cp, subtract the lower specification limit from the upper specification limit, then divide by six standard deviations.
What is process capability CP and process capability indices Cpk )? Explain with examples?
Cp and Cpk measure how consistent you are to around your average performance. The 'k' stands for 'centralizing factor. ' The index takes into consideration the fact that your data is maybe not centered. Cpk tells us what a process is capable of doing in future, assuming it remains in a state of statistical control.