Cellular Scheduling for Batch Production

Abstract

Because multi-product schedules cause complexity in job assignments, the tendency has been to employ additional manpower to cope with the uneven workflow. The present work explores the problem of scheduling batch production in a manufacturing system designed on group ‘technology principles. Four manufacturing cells are designed, and with the aid of a computer, components were processed in batches, through machine cells. Comparison of performance (using the Economic Batch Quantity (EBQ), Rota Cycling of Mixed Products (RCMP) and the Period Batch Control (PBC) methods of batching) were obtained in order to determine the best production policy when components are manufactured for stock. An analysis of the performance of these batching methods led to a better understanding of their relationship and of the role of group technology in batch production management. Some insights are offered with respect to the effect of these batching variables on set-up times in cellular scheduling. Also, some other observations are offered concerning implementation and operational considerations. Data used in the analysis in this study was obtained from a medium sized engineering firm manufacturing various types and sizes of lathe chucks. The company is described and its manufacturing problems presented. Following a detailed analysis of the utilisation of machines in the company's machine shop, a new manufacturing technique, giving improved workflow, is proposed. The final analysis shows that the Period Batch Control batching method is not only superior to the other two methods in relation to the cost of holding stock in the face of fluctuating market demand, but also, in controlling the level of work-in-progress when this parameter is used as a secondary criterion. It is also shown that cells designed for single-line machine configuration are adaptable to multi-product batch production schedules. Within each cell, the daily work assignments of operators are balanced.