Heuristic for Combined Line Balancing and Worker Allocation in High Variability Production Lines

The manufacturing systems are generally categorized into machine-intensive and labor-intensive manufacturing systems. Worker allocation plays an important role in determining the efficiency of a labor intensive manufacturing system. All the efforts in literature are to the address the worker allocation problem in a deterministic condition. However, in many real labor-intensive manufacturing systems such as aircraft companies, there is a high degree of variability in workers’ processing time and quality of performance. Thus, in this paper a method for line balancing with variability in processing time is studied and compared to the ranked positional-weight method. Then, the model is extended further for a simultaneous line balancing and worker allocation in which workers’ different processing time and quality level come to play in a multiple task per station production line. The aim of this paper is to fill the gap between the two problems of line balancing and worker allocation in an uncertain environment by balancing the risk among the stations. Case studies were simulated using QUEST software and the result indicates that risk based allocation has increased throughput and efficiency of the manufacturing line compared to deterministic worker allocation.