Process Capability

The results of most numerically measurable processes will vary around a central value and the 'capability' of the process is defined as the spread of results around this value, with high capability occurring when process results group closely around it. Thus a process that can produce parts to within 0.001mm of a target value is 'more capable' than one which can only produce them to within 0.015mm.

The most common measure of this spread is standard deviation, and 'Process Capability' may be defined as the range between three standard deviations either side of the average.

See also:

Toolbook chapter: Process Capability