Minimising throughput loss in assembly lines due to absenteeism and turnover via work-sharing

In this paper we analyse the loss of throughput rate of assembly line caused by slow pace of substitute workers (replacing absentees) having no prior experience in the required tasks. We proposed work-sharing mechanisms that improve the balance of the workload during the learning period. The proposed mechanisms add to the experienced neighbouring workers some of the workload of the inexperienced worker substituting an absentee. We call this workload shared work'. After the performance of the substitute workers improves due to learning, the shared work is re-assigned to them (relieving their experienced neighbours). We provide analytic expressions for the line throughput rate, which is determined by sets of bottleneck workstations. These sets of consecutive workstations consist of the inexperienced workers replacing the absentees and the experienced workers assisting them during the learning periods. The decision variables of this model are: (1) the amount of shared work, and (2) the time in which the shared work is re-assigned to the substitute worker. Unique optimal values of these two variables are found via numerical study, for buffered and non-buffered lines. Experiments show that the proposed work-sharing mechanisms can significantly improve the line's throughput, compared to the original system without work-sharing.