Risk based worker allocation and line balancing

Abstract

In general, manufacturing systems could be classified into machine intensive manufacturing and labor intensive manufacturing. From the previous studies, we can infer that worker allocation plays an important role in determining efficiency of a labor intensive manufacturing system. Most of the research works in the previous literature is performed in a deterministic bed. But from the time study data that was obtained from a local aircraft company shows a high degree of variability in worker processing times. Thus this research presents a worker allocation approach which also considers the uncertainty in worker processing times into account. Risk based worker allocation approach is developed for three different scenarios. First scenario is the single task per station balanced production line scenario, where workers are allocated to processes by minimizing the overall risk of delay due to workers. In the second scenario, in addition to worker allocation by minimizing the overall risk, multiple workers are allocated to processes to make the flow of products uniform in a single task per station unbalanced production line. Prior to implementing the final approach, a method for line balancing when variability is involved is studied and compared to the ranked positional-weight method. The final scenario developed is a simultaneous approach to balance and allocate workers in a multiple task per station production line. Case studies were simulated using QUEST software and the result indicates that risk based allocation has increased throughput and efficiency compared to deterministic worker allocation.