Abstract
Due to the increase of a variety of demands from downstream customers, the enterprises are necessary to expand more capacity by way of adding more plants or outsourcing. Many companies encounter difficulties in production planning because manufacturing environments have changed from traditional single-plant to current multi-plants. Therefore, the production planners must develop an integrated multi-site planning approach to coordinate all production resources of multiple plants within the enterprise. Because a company may possess many manufacturing plants located in different places geographically, the production planners will face the demand allocation problem in multi-site production planning and scheduling environment. The decisions may involve the manufacturing routings of demand products and production amounts among multi-plants. As a result, a monolithic model of the multi-stage and multi-site production planning problem is proposed in this paper. The contribution of this planning model is to combine two different time scales, i.e., monthly and daily time buckets. In addition, we also consider other practical planning characteristics and constraints which are described by mathematical expressions. For example, production transformation functions, capacity consumption constraints, materials supplying constraints, inventory balancing equations and so on. Through optimization procedures, related production information among the multi-plant network is derived. Besides, an example from a real TFT-LCD (Thin Film Transistor- Liquid Crystal Display) manufacturer case in Taiwan is illustrated for the monolithic mathematical programming model.