SCHEDULING IN CELLULAR MANUFACTURING SYSTEM

Abstract

In the 1970s and 1980s, mass production and mass consumption has been the dominant manufacturing activity in a free economic society. But In order to meet the requirements of diversified market, unpredictable demand, customized products and short product life cycle, individual manufacturing firms must adopt multi-product, small-lot-sized production in order to adapt to changing requirements. Recently, multi-product, small-lot-sized production, which generates a great deal of industrial output, has become the dominant manufacturing activity in the world. In order to cope with difficulties inherent in the multi-product, small-lot-sized production, several effective approaches to the batch type manufacturing systems have been developed. Group Technology (GT) is one of such methodologies. Cellular Manufacturing (CM) is one of the most important applications of GT to production. Although cellular manufacturing provides great benefits, the scheduling task of cellular manufacturing systems is complex for real-life problems. In general Scheduling problem in a cellular manufacturing environment is treated as group scheduling problem, which assumes that all parts in a part family are processed in the same cell and no inter-cellular transfer is needed. But in real life of Cellular manufacturing environment, however, there could be some exceptional parts, which need to visit machines in the other cells. This fact limits the applicability of group scheduling approaches. This work addresses the scheduling of manufacturing cells in which parts may need to visit different cells. A two-stage heuristic algorithm is proposed to solve this problem. These stages are intra-cell scheduling and inter-cell scheduling. Through intra-cell scheduling, the sequence of parts within manufacturing cells is determined. However, in inter-cell scheduling, the sequence of cells is obtained. In this work, various production factors are considered. These production factors include parts processing time, set up time of each machine in each cell where it is used. Using these factors make-span-time of a batch has been calculated. The performance of proposed algorithm is evaluated which appears to perform well regardless of problem size.