Abstract: Existing studies on workers and task assignment in a Seru system usually focus on improving production efficiency, which may cause workload imbalance among workers. To cope with this issue, with the aim of mitigating workload imbalance among workers, this paper jointly optimizes multi-skilled workers and task assignment in a Seru production system with the consideration of lot-splitting. A mixed-integer nonlinear programming model is proposed to minimize the maximum workload of workers. To verify the effectiveness of the proposed model, comparison models without lot-splitting and with lot-splitting but optimizing production efficiency are built. By introducing continuous variables and inequalities, these models are linearized and solved by optimization solver CPLEX based on different-scales instances. Numerical experiments show that compared with the model without lot-splitting, our model has better performance in improving the fair distribution of workers’ workload, with an average reduction of 5.40% in maximum workload of each worker, while maintaining a high level of production efficiency. The studied results can not only supplement the existing optimization theory of a Seru production system, but also provide more valuable guidance for actual production decision-making of enterprises from the perspective of workload equity.

Key words: Seru production system, lot-splitting, multi-skilled worker assignment, mixed integer nonlinear programming