Hybrid flowshop scheduling with setup times for cold treating process in Baoshan Iron & Steel Complex

Seamless steel tube, including multi-variety and multi-specification products, requires variously complicated operations in the whole production process, especially in the cold treating process (CTP). This paper takes the seamless tube plant of Baoshan Iron and Steel Complex as the research background. Considering the practical production constraints, CTP scheduling problem can be viewed as a hybrid flowshop scheduling problem with sequence-dependent setup time. We formulate it as a non-linear mixed integer programming model(NMIP) with multi-objectives. Then a two-stage heuristic algorithm based on modified GA and local search method is proposed to get near-optimal solution of large-scale NMIP problem. Finally, computation experiments with real production instance are carried out to test the efficiency and performance of algorithm. The simulation results show that proposed model and algorithm can be implemented as an effective method to generate optimized scheduling scheme in the CTP scheduling system.