Storage Equipment (I) - Pallet Racking

Basically, racking is one of the equipments that contributes to the storage system of the distribution centre, ensuring it to be well-designed by making use of the volume available, providing proper access to the stored goods through facilitating the throughput of goods as well as minimizing the distance traveled. Furthermore, the use of this equipment will also minimize the risk of insecurities towards damage and deterioration of goods.

There are several choices of racking medium depending on the physical characteristics; risks of hazard, deterioration and hazard; values of the goods. Furthermore, the capital availability of users, characteristics of the available storage methods and equipment as well as the stock and throughput levels must be taken into consideration.

Below are elaborations of several types of racking used by most warehouses and distribution centres throughout the world.

Selective Pallet Racking
This pallet racking is most generally used. This is due to it easy access to every load and flexible choice providing 100% selectivity to every load. This equipment is mainly for the best access and high-demand product. Although it delivers maximum access to stored pallets, it requires numerous aisles and aisle space, resulting in lower storage density than other form of racking.

A type of a selective pallet racking is the boltless selective pallet, which in-demand due to its tool-free assembly, fast and affordable price. However, initial savings can be offset by high replacement and maintenance costs as it is found that the open-back roll formed columns don’t withstand the impacts of fork truck.

Drive-through Pallet Racking
This type of pallet racking is used for storing pallets of a similar stock-keeping unit (SKU) or goods. In this racking, loads are supported by rails attached to vertical frames, and lift trucks are driven between the frames to enter the rack from either side to pick up or pull out pallets as pallets can slide backwards on a continuous rail, open at both ends, which thus, allowing ‘first-in, first-out’ storage.

Drive-through pallet racking is used when there are seasonal items moving quickly out of the inventory and when there are large amount of similar items that can be stored in a single pallet position. It is not encouraged using this equipment when storing a wide variety of loads in the rack. Although selectivity is forgone, storage density is improved due to the ability to store a large amount of similar loads in a smaller area.

Push-back Pallet Racking
The objective of the push-back pallet racking is to minimize empty pick faces or honeycombing. The ideal appliance of the racking will be where all loads in a row are alike and not critically in a ‘first-in, first-out’ stock rotation.

This racking has the same storage density as the drive-through racks and up to 90% more product storage than selective pallet racking systems, but with greater selectivity of 4 times more than the drive-in pallet racking. Due to these factors, it improves the speed of pick rates. Besides offering a large target for loading and unloading, it also maximizes space through storing a range of SKUs on different levels of lanes for convenient access of goods.

Here’s how it operates:

Loads in each row lie on a cart by forklift on an inclined rail sloping gently toward the front. When a new load is deposited into a lane, it ‘pushes back’ the loads already at the face and those behind. When the load is picked, the forklift takes out the front pallet, allowing the pallets on carts behind it to roll gently to the front of the rack, showing a "push back" momentum. The nested carts of the racking make position and retrieval of loads convenient.