How can I improve Cpk value, when it is less than 1.0?
First, compare Cpk to Cp. If Cpk is less than Cp and Cp is greater than one, center the process in the specification. This should make Cpk comparable to Cp. If Cp and Cpk are less than one, there are two actions you can take. The first (an unadvisable one) is to widen the specification particularly on the side that has the spec limit closest to the center of the process (). The second and more advisable answer is to improve the process by reducing variation in the process. If the process is off-center, it would be advisable to try to center it as you try to improve it. Gordon Constable Ph.
