Optimization-based scheduling of flexible manufacturing systems for apparel production

In the mid to high volume apparel production, garments are typically grouped into production lots, and each lot is processed in its own manufacturing cell. A flexible manufacturing system used in this environment enables quick cell configuration, and the efficient operation of cells. The scheduling problem is to decide when to set up a cell and consequently begin garment production in the cell, and to decide the quantity of machines to allocate to each cell. In this paper, an integer programming model is developed which integrates scheduling and resource allocation. The model is solved by using the Lagrangian relaxation technique, and a new bundle method is used to optimize the Lagrangian dual function. Testing is performed using data from a real factory, and numerical results show that high quality schedules are efficiently generated on personal computers