Production-ratio oriented optimization for multi-recipe material handling via simultaneous hoist scheduling and production line arrangement

In multi-recipe and multi-stage material handling (M3H) processes, such as electroplating and polymeric coating, the productivity maximization under a customized production ratio of different types of jobs is an ultimate goal. Cyclic hoist scheduling (CHS) is certainly the most concerned aspect to improve the productivity. However, the production-ratio oriented productivity not only depends on the hoist scheduling, but also substantially relies on the production line arrangement (PLA), i.e., the spatial allocation of various processing units. This is because PLA determines the traveling time for the hoist to perform loaded and free moves among different processing units, which in turn inevitably affects the cyclic scheduling time and thus the total productivity. Therefore, CHS and PLA should be simultaneously optimized for the production-ratio oriented productivity maximization for M3H processes.In this paper, an integrated modeling methodology for productivity maximization of M3H processes has been developed with simultaneous consideration of CHS, PLA, and the customized production ratio. It introduces an MILP model that can successfully address all the major concerned issues for M3H processes, such as multiple recipes, multiple jobs, multi-capacity processing units, diverse processing time requirements, production line arrangement, and the customized production ratio in each cycle production. The efficacy of the proposed methodology is demonstrated by various case studies with in-depth analysis.

► A new MILP model is developed for productivity maximization of multi-recipe and multi-stage material handling processes. ► Hoist scheduling and production line arrangement are simultaneously optimized for the M3H processes. ► The methodology can be applied to any production-ratio oriented productivity maximization problems.