Suboptimal scheduling of injection molding process using fuzzy optimization technique

In this study, a fuzzy optimization based method is presented for scheduling, with possible machine failures, the jobs on an injection molding plant where the machine configuration and the routing of jobs are what the literature usually refers to as a flexible flow shop. Based on fuzzy optimization theory, the problem is first converted to a crisp optimization problem. To solve the problem efficiently, the Lagrangian relaxation technique is employed. The multipliers are then updated by means of a subgradient method. The performance of the fuzzy algorithm was also developed and its performance was evaluated by comparing the results of the scheduling by the fuzzy algorithm with those by the corresponding crisp and existing one