Task proximity index: a novel measure for assessing the work-efficiency of assembly line balancing configurations

Abstract

Assembly line balancing (ALB) aims at optimally partitioning the total work required to assemble a product to workstations. In this problem, precedence constraints must be observed on the sequence with which the distinct tasks of the assembly process may be carried out. In contrast to the strict mathematical posture employed in conventional ALB approaches, this paper provides a deep insight on the origin of precedence diagram which illustrates precedence constraints among the tasks. Our review on assembly planning methods reveals that these constraints are deduced from the geometry of the components to be attached, their position in the assembled product and even planner's expertise on the rational order with which the tasks are to be performed. Accordingly, it is explicitly shown through a case study of a real industrial product that the topology of tasks on the precedence diagram may be utilised to obtain more work-efficient ALB configurations. To this end, a metric system is developed to quantify the proximity of the tasks on the precedence diagram and a novel measure, namely the task proximity index, is proposed for assessing ALB solutions from a practical viewpoint.

Keywords:

• assembly line balancing
• precedence diagram
• index of work relatedness