An effective heuristic algorithm for the optimal turned-out slab pile problem

Slab yards can be used to store slabs produced in steel making-continuous casting process and required to form strips and plates in the hot rolling mill. A slab yard can be divided into a large number of logical sections each containing many pile locations. Slabs are identified in the slab yard according to the pile location. The optimal turn-out slab pile (TOSP) problem is to determine N slabs from M related pile locations so that the total turned-out slab pile number can be minimized while the corresponding slab sequence requirements of the rolling mill are satisfied. This paper first gives the definition of the optimal TOSP problem. Then, a new multiple loop heuristic algorithm is constructed and implemented. The computational experiments with 200 selected problem instances produced randomly show that the new proposed heuristic algorithm performs better than the old one. The average optimality of the algorithm is enhanced by 20% and the computation time is reduced by about 50%. The new algorithm not only increases the shop floor productivity, but also cuts down greatly the workload.