Using Buffers and Work-sharing for Minimizing Makespan of Small Batches in Assembly Lines Under Learning Effects

The effect of workers’ learning curve on production rate in manual assembly lines is significant when producing relatively small batches of different products. This research analyzes this effect and suggests applying work-sharing among the workers in such an environment to improve the time to complete the batch, namely, the makespan. Work-sharing refers to a situation where adjacent workers help each other in order to reduce idle times caused by blockage and starvation. The effect of work-sharing and existence of buffers on the makespan is examined and compared to a baseline situation, with no work-sharing and buffers. We present mixedinteger linear-programing (MILP) formulations, which minimize the makespan and provides optimal work allocation. A numerical study is conducted and the results along with some operational insights are presented.