Abstract
A hybrid scheduling model for production systems including both parts machining and assembly operations is studied. Several products of the same kind are ordered to be produced and parts for the products are manufactured in a flow-shop consisting of multiple machines and assembled into products in a single assembly station. Setup operation and setup time are needed when a machine changes from production of one item to another. Operations are divided into several blocks. Each block consists of parts machining operations and assembly operations(s) for one or several products. Machining of parts of the same item in each block is executed successively. In this paper, the objective function or the measure of performance is the mean completion time of the products, and the problem to decide the block size and permutation of parts machining operations to minimize the objective function is considered. A technique to get better lower bound, and the procedure of branch and bound with it, are developed and a new approach using pseudo-dynamic programming named by the author is proposed in order to obtain a near optimum schedule. The meaning of the model is demonstarted by numerical examples and the effectiveness of the proposed calculation procedure is shown by several computational experiments.
