Maintenance scheduling for flexible multistage manufacturing systems with uncertain demands

This paper proposes a maintenance scheduling method for the flexible multistage manufacturing system in multi-specification and small-batch production. The bi-directional interactions between the production and the deterioration of the station, and the uncertainty of the future production demands are mainly involved. The workload of each station changes with the dynamic production schedule, which will have a marked impact on the deterioration of the station. Meanwhile, the deterioration state of the station will in turn influence the selection of the station to complete the production tasks. Based on this interaction, a load integrated deterioration model is established, and then a cost-effective maintenance scheduling model is proposed for the system. Because of the uncertainty of the future production demands, the optimal preventive maintenance scheme for the system is obtained by minimizing the expected total maintenance cost per unit time within the next uncertain production period. To simplify the solving process, a greedy constraint algorithm is developed, with the duration of preventive maintenance being as the constraint. Numerical comparisons show that the expected total maintenance cost under the proposed maintenance scheduling model is always lower than the one under the full load model and the average load model.