Multi-period operator assignment considering skills, learning and forgetting in labour-intensive cells

Abstract

Abstract This paper deals with assigning operators to various operations in a labour-intensive cellular environment. The operator skill levels and skill-based operation times are used as opposed to the classical approach of using standard times. A three-phase approach is developed to tackle the entire problem: (1) finding alternative cell configurations; (2) loading cells and finding crew sizes; (3) assigning operators to operations. A multi-period analysis is performed to study the main issues in this paper. Mathematical models are used in all phases. Two heuristic approaches (Max, MaxMin) are developed for operator assignment in phase III. Both heuristics are compared and their impact on operator learning and forgetting is also investigated. Results show that the proposed approaches in operator assignment outperform the classical approach of using standard times. Heuristic Max resulted in lower makespan and higher idle times whereas heuristic MaxMin improved operator skills more uniformly. Keywords: Cellular manufacturingOperator assignmentMathematical modelingHeuristicsSkills