Production Scheduling Optimization Algorithm for the Steel-Making Continuous Casting Processes

This paper investigates the steel-making continuous casting (SCC) scheduling problem. SCC is a high temperature and large-scale process with batch production at the last stage that was identified as the key process of modern iron and steel enterprises. This paper presents a mathematical model for scheduling the SCC process. The model is developed as a Mixed Zero-One Linear programming (MZOLP) according to actual situations of SCC. The objective is scheduling a set of charges (jobs) to minimize the earliness and tardiness penalty costs as well as the charge waiting time cost. The solution methodology is developed based on a Branch and Bound (B B) algorithm. A heuristic method presented at the beginning of the search to compute an initial upper bound. A lower bound and an upper bound are developed and a method for reducing branches is established based on the batch production in the continuous casting (CC) stage. Moreover, branching schemes are proposed. The B B algorithm presenting the initial upper bound, the lower and upper bound, the method for reducing branches, and branching schemes is tested on a set of instances. The analysis shows the efficiency of the proposed features of the algorithm.