A Heuristic Algorithm for Solving Multi-crane Scheduling Problem in Batch Annealing Process

This paper investigates the scheduling of the multi-crane operations in batch annealing process in an iron and steel enterprise so that the completion time of the last annealed coil (makespan) is minimized. The annealing process of each coil consists of two-stage: heating and cooling. To start heating (cooling) for each coil, a special machine named furnace (cooler) must be loaded on. Once the heating (cooling) is completed, the furnace (cooler) must be unloaded immediately without any delay by crane (job no-wait constraint). The aim of our studied problem is to schedule finite machines (furnaces and coolers) by cranes to process jobs under the consideration for avoiding collision between two adjacent cranes and satisfying job no-wait constraint. For solving the problem, we present a heuristic algorithm combining earliest job requirement and closest crane first. Through the theoretical analysis, we show the absolute performance bound of the proposed heuristic algorithm.