Stowage decisions in multi-zone storage systems

The stowage decision determines how arriving products are distributed in a storage system or warehouse. In particular, we consider the zone-stowage decision for large warehouses that are organised into distinct storage zones. An example would be a multi-floor warehouse where each floor is a storage zone. Each storage zone has limited picking capacity; we want to stow the product inventory across the storage zones so as to be able to meet uncertain demand requirements with the limited picking capacity in each zone. Determining how to spread the inventory across the storage zones is the zone-stowage decision that we consider in this paper. With a simulation study, we identify two zone-stowage policies that are effective in balancing the picking workload across different storage zones. The first zone-stowage policy achieves a chaining-inspired allocation by splitting the received quantity for each product across two storage zones; the second zone-stowage policy explicitly tracks the expected workload for each storage zone, termed the velocity of the zone, and then stows arriving products to the storage zone with the smallest velocity. Key Words: Stowage Decision, Storage Systems, Flexibility, Warehousing System