Authors: Gürsel Süer, Najat Almasarwah, Omar Alhawari, Casey Davis   Publication date: 2020/10/1   Journal: Journal of Manufacturing Systems

Abstract:

In a manufacturing facility, the decision maker considers customer satisfaction as an essential priority in which customer due dates should be met. The cell loading, scheduling and the total manpower are considered among the main decisions in a manufacturing system. Three performance measures are studied in this paper and they are the number of tardy jobs, total manpower, and average flow time. Two approaches are proposed to handle such performance measures. In the first approach, lexicographical analysis is proposed to achieve the objectives, when the performance measures are not equally important. A three-phase methodology is introduced. In the first phase, a mathematical model has been used to maximize the output rate by allocating manpower to operations for several manpower levels. In the second phase, another mathematical model is developed based on the results of the first phase to minimize total manpower such that no job is tardy (i.e., the number of tardy jobs (NT = 0)). In the third phase, a mathematical model is also proposed to minimize the average flow time based on the results obtained in the first and the second phases. The second approach allows varying weights for minimizing average flow time and total manpower subject to zero tardy jobs due to considerations for customer satisfaction. Thus, a two-phase methodology is followed, and a bi-objective fuzzy mathematical model is developed. Two-phase methodology produced similar results to three-phase methodology for certain values of weights assigned to performance measures. Three-phase methodology was efficient for lexicographical analysis. Furthermore, the number of cells in the system is affected by the nature of due dates. The number of cells and total manpower increase when the due dates are tight and decrease when the due dates are relaxed.