Heuristic Procedure for Two-Criterion Assembly Line Balancing Problem

Abstract. A heuristic procedure for solving the two-criterion assembly line balancing (2CALB) problem is presented in this paper. Its objective is to assign assembly tasks to workstations so as to concurrently balance the workstation processing time and the postural and physical loads (PPL) among assembly line workers. The procedure consists of two stages. Firstly, the classic Kilbridge and Wester’s algorithm is utilized to develop an initial task–workstation assignment solution based on the workstation processing time. Secondly, the task reassignment algorithm is applied to rearrange assembly tasks assigned in the first stage in order to balance the PPL among workers. A composite index of variation is developed as a weighted measure of the normalized variance of the workstation processing time and that of the PPL. Using a clothes assembling example, four assembly line designs (based on the number of workstations) and nine criterion weight pairs are investigated. A sensitivity analysis of the composite index of variation and changes in the line throughput and efficiency are also discussed