A production planning model for reconfigurable lines

Abstract

A key indicator of the efficiency of a production line is cyclic idle time. Manufacturers use heuristic line balancing techniques to determine the allocation of elemental tasks to workers so as to minimize labor costs. The productive, i.e. non-idle, portion of each cycle then reflects the efficiency of the line. Line balancing techniques determine the allocation of tasks based on a prespecified throughput. When demand changes however, the line may have to be reconfigured to reflect the new desired flow rate, resulting possibly in a lower efficiency and a higher per-unit labor cost. This raises an interesting question: should one use a flow rate that corresponds to the higher efficiency, handling any mismatch with demand through the use of inventory or backordering, or should the aim be to match flow rate precisely with demand rate even though the resulting efficiency might be lower? This paper proposes an answer to this question by embedding line balance and efficiency into the framework of a well-known production planning model. A heuristic method for solving the extended model is developed, and its application demonstrated using numerical examples.