Introduction
Many companies store their products on pallets in the warehouse, and there are some pallet storage methods that allow the warehouse staff to store pallets efficiently. Common pallet storage systems include:
Block stacking
Stacking Frames
Single-deep pallet rack
Double deep rack
Drive-in rack
Pallet flow rack
Push back rack
Block Stacking
Block stacking refers to unit loads stacked on top of each other and stored on the warehouse floor in lanes or blocks. The pallets are stacked to a specific height based on some criteria such as pallet condition, the weight of the load, height clearance and the capability of the warehouse forklifts.
The pallets are retrieved from the block in a last in, first out (LIFO) manner. This does not allow for removing stock based on date basis or first in (FIFO). Removal of stock can cause honeycombing to occur where empty spaces occur that cannot be filled until the whole lane is empty. This method is cheap to implement as it involves no racking and can be operated in any warehouse with open floor space.
Stacking Frames
Pallet stacking frames are made up from decks and posts that can be erected and moved if necessary. The stacking frame allows pallets to be stored several high and is particularly useful when the pallets to be stored are not stackable.
Many companies will use stacking frames in the warehouse when they need temporary racking during busy period periods. With stacking frames, the issue of honeycombing exists similar to block stocking.
Single-Deep Pallet Rack
Single-deep pallet racking provides access to each pallet stored in the rack. This gets around the honeycombing issues of stacking frames and block stacking. When a pallet is removed, the space is immediately available for a new pallet to be placed in that space. This type of racking can be configured in any number of ways with various heights. Most warehouses today have this type of racking in use. The major disadvantage is that the racks require significant floor space for suitable aisles.
Double-Deep Pallet Rack
The double-deep pallet rack is a variant on the single-deep rack that incorporates two single racks that are placed together. This reduces the number of aisles required but this type of racking is susceptible to honeycombing, so may not be as efficient as single-deep racking. Also, a double reach forklift is required to place and remove pallets from the racking.
Drive-In Rack
Drive-In racks provide five- to 10-pallet load spaces similar to the double-deep racking. The drive-in lanes provide access for the forklift to place and remove stock. However, the forklift has a limited space to maneuver, and this increases the time required to place and remove pallets. The drive-in rack is similar to block stacking as the LIFO principle is used for pallet retrieval.
Pallet Flow Rack
The pallet flow rack operates whereby the load is moved from one end of the rack on a conveyor that allows the pallets to be removed in a FIFO manner. Once a pallet is removed the next pallet moves into the position of the pallet that was removed. This racking solution is suitable for warehouses that have high throughput but is an expensive option. But is an expensive option.
Push Back Rack
The pushback rack is a LIFO solution where the load is placed into storage using a rail-guided carrier. When a load is placed into storage, the load pushes the other loads back into the storage area. When a load is removed the next load in the lane moved to the position where the other load was removed. This means that each lane with stock has a load in the optimum position for removal. This racking method may not be suitable for warehouses that require FIFO.