Operating Curves of Manufacturing Systems: A Theoretical Discourse

To assess the performance of a manufacturing system is not as easy as it seems at first. Besides common key performance indicators (KPI) mainly so called operating curves are used to this end. The advantage of the operating curves is that one can study the system behavior under varying conditions. However, the systems cannot be compared with each other so easily. To ensure the comparability of the system behavior the operating curves must therefore be normalized. In this paper a method will be developed for defining normalized operating curves, which is also suitable for complex manufacturing system structures. These methods are based on Little’s law as well as a special kind of flow graphs, with which it is possible to find the limiting bottlenecks in the system under special conditions. An example will explain that the method works.