| The lot size/scheduling situation can be described as determining how many of each product to produce, the lot size, and when to produce each product, the schedule. When more than one product is produced at one resource sequencing or determining the order in which the products will be produced becomes an additional factor.; Today, most lot size/scheduling techniques proposed in the literature have as their objective to minimize the sum of setup and inventory holding costs. However, in the short term, setup costs are often fixed expenses and holding costs are not calculated consistently between firms and often are not an accurate measure of the costs of holding inventory. The suggested problem solutions result in infrequent setups for most products and underutilization of capacity leading to long lead times and large lot sizes.; In this research a lot size/scheduling model is created which minimizes the planning period setup time and average inventory holding time rather than economic measures. A heuristic algorithm is created to reduce the computation time necessary to solve the model. Extensive testing has shown the heuristic algorithm consistently provides feasible, close to optimal solutions. The resulting cycle time and lot sizes for the products is considerably less than those found in the results of the economic models and production closely matches immediate demand. This is consistent with the objectives in manufacturing today where Group Technology, Cellular Manufacturing Systems and Just-in-Time concepts all seek to produce just the products that are needed when they are needed. |
