Aggregate line capacity design for PWB assembly systems

In a multi-product, flexible manufacturing environment, line capacity of pr inted wiring board (PWB) assembly systems may need to be adjusted at the be ginning of each aggregate planning period because of demand fluctuation ove r multiple periods. A model of production planning and equipment changeover scheduling at the aggregate level is developed. In the described model, th ree kinds of equipment changeover methods, i.e. adding machine, removing ma chine and transferring machine, are involved. Because the model is a large- scale integer programming problem, it cannot be solved directly. A solution approach is developed, which first solves a recursive linear programming p roblem to obtain a rough set of machines to be added and a rough set of mac hines to be removed for each machine line in each period, then applies a br anch and bound heuristic to the rough sets to obtain near-optimal solutions to the equipment changeover scheduling problem. Computational studies show the financial benefit both on capital cost and equipment changeover costs.