Maximizing average efficiency of process time for pressure die casting in real foundries

Scheduling of casting processes is the problem of determining the number of products that will be manufactured in each casting shift so as to optimize a predetermined objective function. In this paper, we propose a linear programming (LP) model that maximizes the average efficiency of process time for casting in real foundries. The considered casting process is pressure die casting, the most prevalent permanent mold casting process, equipped with an automated die exchange device. In permanent mold casting, the use of a mold or die installed on a casting machine requires a significant process time for casting. The objective function of the proposed LP model is defined as the average ratio of the actual process time to the pre-assigned operating time in a shift. A solution that minimizes the objective function will provide the maximum surplus time, hence optimizing the efficiency of casting operations in terms of process time. Numerical examples are presented to illustrate the applicability and reliability of the proposed model. The results demonstrate that this model is an effective and conveniently implemented tool for solving real casting sequences in a simple and practical framework.