Models for cell loading and product sequencing in labor-intensive cells

This paper focuses on cell loading issues and product sequencing in labor-intensive cells. In labor-intensive cells, there are usually more operators than number of operations and cells usually consists of simple and light-weight machines and equipment. A three-phase methodology is proposed to deal with this problem. The objectives considered are minimizing makespan, total machine requirements, and intra-cell manpower transfers. In the first phase, optimal manpower allocation to operations is determined for each product. Then, similarity among products is established based on the similarity of operator/machine levels. The second phase involves cell loading to minimize makespan and machine requirements. Two mathematical models are developed to accomplish these tasks. One mathematical model (model A) does not allow product splitting whereas model B allows product splitting. Finally, third phase treats the product sequencing problems as traveling salesman problem (TSP) where the objective is to minimize intra-cell manpower transfers. Experimentation is performed and the results are compared with those of a heuristic procedure developed earlier. The results show that model A or model B can be chosen over the heuristic procedure.