Batching and production planning – A project planning problem with sequence-dependent setup costs

In discrete production as well as in the process industry machines or plants are often arranged in a certain operating or setup state. In both areas of production planning the expressions “batch” and “batching” are used if single material quantities or jobs require the same setup state and are grouped in order to reduce the number of changeovers. However, the use of these expressions is not always consistent. In this paper both areas of production planning are analysed. Based on the derivation of synonymic expressions consistencies and differences are determined. For a specific problem that occurs both in discrete production and in the process industry a mathematical model is formulated adapted from the well-known resource-constrained project scheduling problem while sequence-dependent setup costs are included. A priority rule based heuristic is described and applied to a real-world planning problem in the steel industry.