A comparative study of the performance of pure and hybrid group technology manufacturing systems using computer simulation techniques

Abstract

Problems of workload imbalance in Group Technology (GT) can be mitigated by transferring workloads from a congested machine centre in one cell to an alternative, less congested machine centre in another cell. Such inter-cell workload transfer results in a GT system which is a hybrid between pure GT (in which components are. completely processed within a cell) and functional layout (FL) (in which components are routed from one department of similar machines to another until completely processed) Though inter-cell workload transfer is often used in practice, its effects on system performance in GT have not been evaluated. This paper describes a general purpose GT simulator which has been developed and the evaluation of workload transfer which has been carried out (Aug 1981). Various job and cell attributes are employed as criteria for initiating workload transfers and the results of such transfers are examined in terms of job satisfaction, scheduling effort and material handling as well as overall shop performance. The interacting effects of job allocation rules, priority dispatching rules and batch overlapping are investigated under varying degrees of deviation from ‘pure’ GT. The effects of changes in job mix and of increases in demand are also examined. So are the effects of unbalanced capacity and cell size. The implications of the results for the practical design and operation of GT systems are also discussed