Batch scheduling in a two-stage flow shop with parallel and bottleneck machines

Abstract

In this paper we consider a scheduling problem where a set of jobs are simultaneously available for processing in a two-stage flow shop with parallel and bottleneck machines. The first stage has a number of identical parallel machines, while the second stage comprises a bottleneck machine operating according to a round-robin discipline. All jobs are processed on both machines in batches, subject to side constraints. The objective is to minimize the makespan, i.e. the maximum completion time of the jobs. We model the problem as an Integer Linear Program. We then exploit some properties in order to devise approximate algorithms. These procedures have been tested on a set of real-world instances provided by an Italian leather firm. Computational results show that our heuristics are able to provide high quality solutions in a reasonable amount of time.