Cubic Inventory Storage and NWC

July 21st, 2009

How many rack bays are needed to satisfy the cubic inventory storage requirements, on average and at a peak? What height of building is required to efficiently store the required inventory?The necessary storage volume is often expressed in terms of cube (square footage).  The ability of a distribution center to efficiently store cube is defined as net working capacity (NWC).  Once pick-slot requirements have been determined and converted into rack bays, the cubic inventory on hand will determine the required height of the bays, and thus the entire building size.  The NWC is then calculated at varying building heights to ensure that inventory will fit overhead of the pick slots. In some designs, where inventory levels are very high, special dense storage sections may be added to the DC layout in order to minimize stacking height requirements.

It is always vital to hold inventory for a given item as close as possible to its designated pick location(s).  This minimizes the amount of put-away and replenishment labor required to stock the pick slot.

The travel aisle spacing between rack bays is dictated by the mobile equipment meant to operate within a given aisle. Generally, fork lift equipment outrigger dimensions will vary with the required lift height at which product is placed in overhead reserve locations.  The allowance for operators to pass easily in an aisle will determine the final aisle width. Passing is a requirement for efficiency as it prevents an operator being impeded by another from performing their function. A typical, conventional facility with a clear height range from 28′ to 35′ will have a minimum 10′6″ aisle width for single-deep pallet racking.

Entry Filed under: Design & Layout, Distribution Operations