Workload Balancing for Stability Test Using a Mixed Integer Programming Model.

This research studies a monthly task assignment for staff and testing equipment of a stability testing process in a pharmaceutical company. A stability testing process begins with collecting drug to the system, preparing chemical, glassware and equipment, testing drugs on equipment and writing reports. There are three types of a stability test where each drug requires different type of stability test, and some drugs require multiple types. Each testing process requires different types of testing equipment, which requires different set-up time and processing time. Currently, task assignments are determined based upon division manager's experience which leads to unbalanced workload. To solve this problem, a mixed integer linear programming model (MILP) is proposed to find the optimal solution, which focuses on minimizing the difference between maximum and minimum workload of staff, overtime, and penalty cost of postponement. The result of this model shows that the unbalanced workload among staff is reduced. Moreover, by test postponement, overtime does not occur. [ABSTRACT FROM AUTHOR]