A hybrid algorithm to solve the problem of re-entrant manufacturing system scheduling

Manufacturing system scheduling is an important field in both of production management and optimization. This system involves many facilities which execute jobs operations. In this paper, the problem of re-entrant manufacturing system scheduling is considered. A scheduling method is elucidated for the re-entrant manufacturing systems, where the process route of a job passes through production facilities one or more times. The maximization of the production rate in order to maximize the output of the system is considered as a main objective of the scheduling problem and the minimization of the work in process is considered as the second objective. Since this problem is well known as NP-Hard class, a bi-objective algorithm which uses the simulated annealing algorithm is developed to solve medium and large size problems. Moreover, a mixed integer linear programming method is presented which can solve the small size problems. The proposed method makes a cyclic schedule, where an adequate number of jobs are treated as a lot and the lot is cyclically released into the system. To evaluate the validity of the proposed algorithm, results are compared with the optimal solution and some presented methods. The computational results validate the efficiency and effectiveness of the proposed algorithm. So, the proposed algorithm can be applied easily in real factory conditions and for the large size problems. So, it should be useful to both practitioners and researchers. (C) 2011 CIRP.