A Study on Hybrid Flow-shop Scheduling with Assembly Operations

Abstract

Hybrid scheduling for the production system including both of parts machining and assembly operations is studied. Several products of different kind are ordered to make and parts for the products are manufactured in the flow-shop consisting of multiple machines. Each product is produced by hierarchical assembly operations from the parts, that is, some parts are assembled into the first sub-assembly and some other parts and the first sub-assembly are assembled into the second sub-assembly, and so forth. In this paper, the problem to obtain a schedule having minimum weighted sum of completion time of each product is introduced. A technique to gain better lower bound and a calculation procedure using branch and bound method are developed to get an optimum or near-optimum schedule. Meaning and validity of the model are clarified by a numerical example and effectiveness of the proposed calculation procedure is shown by several computational experiments.