Combined production and maintenance scheduling for a multiple-product, single-machine production system

Traditionally, the problems of equipment maintenance scheduling and product ion scheduling in a multi-product environment have been treated independent ly. In this paper, we develop a Markov decision process model that simultan eously determines maintenance and production schedules for a multiple-produ ct, single-machine production system, accounting for the fact that equipmen t condition can affect the yield of different product types differently. Th e problem was motivated by an application in semiconductor manufacturing. A fter examining structural properties of the optimal policy, we compare the combined method to an approach often used in practice. In the nearly 6,000 test problems studied, the reward from the combined method was an average o f more than 25 percent greater than the reward from the traditional method.