Buffer and cyclical product sequence aware assembly line balancing problem: Model and steady-state balancing case study

Mixed model flow-shops often operate cyclically and may have buffers to absorb differences between product models. Balancing task distributions in regard to such aspects is challenging and key to achieve steady-state efficiency (average production rate). Tests reported herein have shown that current balancing models for this problem lack the ability to properly represent steady-state. This paper presents a new MILP model to address this problem and balance the flow-shop for steady-state. The model was applied to data from a real world case study and solved to optimality with a universal solver. A simulation model validated the mathematical model’s exact steady-state prediction. The achieved optimal balancing was different for each considered buffer layout and product sequences, furthermore finite buffers allowed to achieve, in one case, maximum theoretical steady-state efficiency. Finally, the presented model allows steady-state optimization without requiring multiple replications of the product sequence, outperforming makespan minimization variants.