Optimization of flexible job-shop scheduling with weighted tardiness and setup-worker load balance in make-to-order manufacturing

This paper describes the optimization of a flexible job-shop scheduling problem (FJSP) in small and medium-sized enterprises (SMEs) with make-to-order (MTO) manufacturing of products of many kinds. Incorporating weighted tardiness and setup-worker load balance into the objective function of the problem, we have developed a genetic algorithm (GA) using the island model as an optimization method and conducted a study based on production data of actual MTO manufacturing SMEs. We compared the solutions of the GA developed with the values obtained from schedules for the earliest due dates (EDD) that prioritized only the due dates and confirmed the effectiveness of the proposed method Additionally, we conducted numerical experiments using this technique on the risks likely to arise in actual companies (resignation of setup-workers and excessive demands of a customer for moving the due date forward) and investment of countermeasures. We confirmed that it was possible to evaluate the effects of risks and countermeasures quantitatively. This method can contribute to the objective business judgment of SMEs providing MTO products and services by incorporating other objective functions.