Monolithic and hierarchical method of scheduling for assembly of multi-option products – comparison of two concepts

Abstract

The monolithic and the hierarchical method are compared in the paper. They are intended to build as short assembly schedules as possible. The methods are constructed for assembly lines with parallel machines and with intermediate buffers. A Fixed and an alternative assembly routes are regarded. The most important, distinctive feature of these methods, is that they are provided for multi-option products. Assembly of various products in different variants is the reply to the contemporary challenges faced by the manufacturers, who try to satisfy the demands of individual customers. The hierarchical method consists of two levels. The First level of the hierarchical method is connected with balancing machine workloads. The task scheduling is accomplished on the second level of the method. The mathematical models of integer programming tasks were built for its specific levels. The presented in the paper hierarchical method was compared with the monolithic method. The problems of balancing machine workloads and scheduling are solved simultaneously using the monolithic method. Using integer programming and the monolithic concept allowed to determine optimum solutions. The results of computational experiments with the proposed approaches for scheduling for assembly of multi-option products are presented.

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