Production Scheduling in Food Freezing Process Under the Effect of Freezer-Door Opening

Abstract

In this chapter, a scheduling problem of a freezing process in frozen food industry has been addressed. Freezing times of products are not uniform. Every time that the freezer is interrupted due to freezer-door open either for loading or unloading product trolleys, the freezer temperature will increase caused by the heat transfer. The freezing time of jobs being processed in the freezer need to be extended to cover the temperature loss. Therefore, the loading and unloading schedule of product trolleys in the freezing station affects to the production time and cost. A mathematical model and a heuristic algorithm were developed to determine the suitable production scheduling. The objective function was the minimization of the total cost, including cost of jobs waiting before freezing process, cost of extended processing time due to freezer-door opening, and cost of jobs that need to be delay in the freezer after freezing process has been done. The performance of the developed heuristic was assessed under various scenarios. The results were optimal for all small-size problems and outperformed the traditional First-In First-Out (FIFO) method in practical size problems.