Developing a Matheuristic for the Integrated Planning of a Cold Rolling Steel Plant

Steel-producing firms are confronted with the challenge of determining plans that coordinate production processes across a set of processing stages. While several approaches for integrated planning of hot rolling mills have been proposed, the cold rolling process is still poorly investigated. Therefore, we present a model formulation to simultaneously form campaigns of coils in cold rolling steel plants. The model considers multiple processing stages with unrelated parallel machines, sequence-dependent setup operations and order-specific due dates. To solve the model, we propose a matheuristic based on Fix-and-Relax and Fix-and-Optimize that utilizes a production line-based decomposition strategy. The results of a numerical study are presented that replicates the realistic production environment of a real cold rolling plant and a planning horizon of up to 10 days. The proposed matheuristic consistently outperforms a commercial solver in terms of solution quality and time.