A scheme of supplementary production in linear programming scheduling of die casting processes

The linear programming model for die casting processes provides the optimal production plan that maximizes the average efficiency of melting furnaces. In this article, we address supplementary production in linear programming scheduling of die casting processes. Since a real die casting campaign is subject to a variety of potential malfunctions, there may exist defective items among final cast products, thus failing to match the quantities of customer orders. The objective of this study is to propose a novel scheme of preventing product shortage by manufacturing additional cast products associated with the result of the linear programming model. In particular, supplementary production is practicable by utilizing the residue of molten alloy and cast scraps or remnants available in each shift. The sequence of casting shifts is also adjusted for facilitating this supplementary production. The proposed scheme does not alter any part of the original scheduling result of the linear programming model. A numerical experiment is conducted using real foundry data to validate integrity and performance of the proposed scheme.