Performance of Class-Based Storage in a Unit-Load Warehouse

Abstract

Storage policy performance in a warehouse is usually evaluated through average one-way travel distance or time. By considering the realistic required storage space (RSS) measured in number of locations, this chapter examines the performance of random, full turnover-based, and class-based storage policies for a unit-load warehouse operated by a forklift in single-command mode with a given annual demand volume. A generalized travel distance model with consideration of realistic RSS is developed to describe the performance problem of these policies. According to this model, the results show that on the one hand, the performance of random policy does not keep flat but increases with the skewness of the demand curve because of the effect of realistic RSS. On the other hand, not turnover-based but class-based policy is recommended to warehouse managers because with the consideration of the tradeoff between turnover ranking and space sharing among items, class-based policy performs better than full turnover-based policy. In addition, warehouse managers should adopt a wide-shallow warehouse layout for items with nonsignificantly different annual demands and a narrow-deep layout for items with significant differences because the optimal warehouse shape factor (ratio of width to depth) decreases with the skewness of the demand curve.