An integrative model for automatic warehousing systems

Automatic warehouses, for the most part, have been studied in isolation. This paper departs from this approach by proposing an integrative model in which warehouse activities interact with other functions of the total system. The model has been simulated under three modes of operation: single command, dual command (DC), and hybrid. Simulation results confirm that the length of stay of unit loads outside the warehouse affects performance and also suggests that, under the DC mode, the warehouse may lose stability. Hence, the hybrid mode is proposed as an alternative. The hybrid mode outperforms the DC mode on most performance measures, except that the length of the storage queue at high throughput levels is longer. Finally, saving opportunities, via a reduction in the number of storage/retrieval machines, are discussed.