Process capability is a quality management term and describes the measure of the quality of a machine or process, based on specification limits.
There are two types of process capability studies, PFU for short, to determine the metric.
The preliminary PFU examines a process before series start-up and is used to determine the upper and lower intervention limits for the process. The preliminary PFU examines a process before series start-up and is used to determine the upper and lower intervention limits for the process. The basic prerequisite is the stability of the process.
The process capability is described with a key figure or the index cpk (process capability index).
For evaluation, the customer’s requirements are compared with the results of the process. Here, using a model of the probability of the normal distribution, one calculates the excess proportion.
Both investigations analyze to what extent the manufacturing process fulfills the planned task within the quality requirements. Statements about process capability as well as process controllability (index cp: tolerance / process variation) are needed to eliminate systematic process influences and ultimately to minimize testing and defect costs.