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 r esults. We often overlook the fact that not only the production process, wi th its external and internal influences, is subject to variation, but the m easurement process is as well. The real process situation is falsified thro ugh the "eyes of the measuring instrument" because the uncertainty of measu rement by the measuring instrument overlaps the deviation of the production process. This paper discusses in detail those boundary conditions that mus t be considered and which characteristics of the measuring instrument are i mportant for obtaining sound characteristic values. (C) 2000 Elsevier Scien ce Inc. All rights reserved.