A comparison of scheduling philosophies for manufacturing cells

In this paper the authors compare three approaches for assigning workers to tasks and controlling the movement of jobs through cellular manufacturing systems. The objective is to minimize throughput time for part batches. The scheduling approaches considered include 1) individual machine loading with batches being sequenced on a first come, first served basis; 2) a cell dedication strategy wherein the cell is devoted to a single product type at a time; and 3) a job enrichment strategy where each batch is assigned to a single, cross-trained operator who must perfrom all batch operations. The approaches are compared by queueing approximations and simulation over a variety of conditions. Dedicated cells are shown to perform best when cells are large, with balanced workloads and large lot sizes. Assigning batches to cross-trained workers may produce quality and morale advantages without adversely affecting throughput times as compared to traditional batch handling techniques, particularly if machines are not heavily utilized.