A heuristic method for batch scheduling in the pharmaceutical industry with sequence-dependent setup times

Abstract

The batch scheduling with sequence-dependent setup times is an operational problem of great importance for the pharmaceutical industry as it affects the shop performance and the provided service level. Exact solutions are a time consuming task with increased functional complexity, which calls for heuristic methods while dealing with the sequencing and scheduling of drug batches on a daily, weekly or monthly basis. This paper proposes a modified beam search method which employs dispatching rules for selecting the next batch in the sequence, and evaluates the schedule performance in terms of flow-times and due-date-based measures. The efficiency of the method is justified by using data from a pharmaceutical firm as a real-world test case. Extensive simulation experimentation reveals solutions for the firm which minimise the total setup times responding satisfactory to due-date objectives as well. In addition, it reveals insights for the sequencing and scheduling problem in the pharmaceutical industry.