A measure of process capability, calculated as a ratio of tolerance or specification limits (upper limit – lower limit) divided by the process variation (6 standard deviations).

USL = Upper Specification Limit

LSL = Lower Specification Limit

= Standard deviation (short term, within subgroup)

Example:

If a coating process is sampled with USL = 0.10, and LSL = 0.05, and the standard deviation = 0.01, then the Cp is calculated as:

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