Safety Stock versus Safety Time in MRP Controlled Production Systems
通过随机模型分析MRP系统中安全库存和安全时间两个参数受预测精度、加工时间波动和拥堵程度的影响，发现安全时间仅在能准确预测未来需求时更优，否则安全库存更稳健。
The two management set parameters which determine the performance of a material requirements planning (MRP) system are the lead time and the safety stock. The appropriate values of these parameters are influenced by the accuracy of forecasts over the lead time, the variability of processing time and the degree of congestion, together with the costs of inventory and shortages. These influences are explored using stochastic models of a single stage manufacturing system for which work release is controlled using MRP. The major conclusion is that safety time is usually only preferable to safety stock when it is possible to make accurate forecasts of future required shipments over the lead time, otherwise safety stock is more robust in coping with changes in customer requirements in the lead time or with fluctuations in forecasts of lead time demand.