Abstract: Purchasing and production are important operations for enterprises. Also they have close interaction and it is better to consider them simultaneously. For this purpose, a mathematical model for integrated scheduling optimization is developed. The scheduling includes lotsizing, purchase scheduling, and production scheduling. With this model, a solution method is proposed by combining genetic algorithm with network optimization methods. In the method, chromosome of genetic algorithm provides a framework of lotsizing and production scheduling, while the network model presents purchase scheduling. Numerical results show an excellent performance of the proposed method and it outperforms the traditional hierarchical optimization strategy.

Key words:  lot-sizing, scheduling, genetic algorithm, network optimization