Acceptance of processes: do we need decision rules?

As processes become more complex, the need for improved methods of process optimization increases. To meet this goal, quality management (QM) with its methods, procedures and tools requires repeatable quantitative metrology results. We often overlook the fact that not only the production process, with its external and internal influences, is subject to variation, but the measurement process is as well. The real process situation is falsified through the “eyes of the measuring instrument,” because the uncertainty of measurement by the measuring instrument overlaps the deviation of the production process. This paper discusses in detail those boundary conditions that must be considered and which characteristics of the measuring instrument are important for obtaining sound characteristic values.