Process capability

The ability to produce products or provide services that meet specifications defined by the customer's needs. For example, a manufacturer of photocopiers requires that the width of a rubber roller must be between 32.523 cm and 32.527 cm to avoid paper jams. Capability analysis reveals how well the manufacturing process meets these specifications, and provides insight into how to improve the process and sustain your improvements.

Before assessing processing capability, you must ensure your process is stable. An unstable process is unpredictable. If your process is stable, you can predict future performance and improve its capability.

The capability of a process should be constantly measured and analyzed. Capability analysis can help you answer following questions:

·    Is the process meeting customer specifications?

·    How will the process perform in the future?

·    Are improvements needed in the process?

·    Have you sustained these improvements, or has the process regressed to its previous unimproved state?

Analyze process capability with capability indices such as Cp, Pp, Cpk, and Ppk.