A two-stage heuristic for the sequence-dependent job sequencing and tool switching problem

The job sequencing and tool switching problem is a combinatorial optimization problem that commonly happens in a flexible manufacturing system environment. In this type of environment, a set of flexible manufacturing machines can be configured with various tools to process different jobs and the requirement to switch tools may correspond to a reduction of productivity. Consequently, research on the job sequencing and tool switching problem has been concentrated on minimizing the number of tools switches. This paper discusses the sequencedependent job sequencing and tool switching problem. The sequence-dependent job sequencing and tool switching problem extends the standard model by considering non-uniform setup times since industrial applications indicate that a tool setup time might be influenced by the previously installed tool at the same magazine slot. A two-stage heuristic procedure is developed here. In the first stage, an adaptive large neighborhood search is deployed for finding the near-optimal job sequence. Then, in the second stage, a combination of the Keep Tool Needed Soonest policy and simulated annealing is proposed for the tooling sub-problem. Comprehensive computational experiments are carried out to demonstrate the efficacy and robustness of the proposed method for solving the sequence-dependent job sequencing and tool switching problem.