Types of Flexible Job Shop Scheduling: A Constraint Programming Experiment

The scheduling of jobs is a crucial task in every production company and becomes more and more important in the light of the fourth industrial revolution (Industry 4.0) that aims at fully automated processes. One such problem formulation with big practical relevance is the flexible job shop scheduling problem (FJSSP). Since the classic problem formulation is more general than what can be found in most of nowadays industrial environments, this paper introduces different types of flexibility and investigates how the flexibility type, the amount of allowed flexibility and the presence of machine dependent processing times influence the solution quality that can be achieved by a state-of-the-art constraint solver within limited time. Results show that certain forms of flexibility, higher flexibility factors and the absence of machine dependent processing times can ease the problem.