Re-palletizing
The most efficient method of distribution would be to ship a full truckload or railcar directly from the manufacturer to the retailer. The next most efficient method would be to ship a full truckload to a distribution center, unload full pallets of products, and immediately load the pallets onto trucks destined for individual stores.
Both of these methods can only be used on very high-volume items. Most products cannot be delivered in this manner, and pallets or even individual boxes must be broken down and divided. Once a full pallet must be broken apart, the costs of handling the product can increase quickly.
Many distribution centers use large sortation systems with miles of conveyor to move products through the facility and into a truck. They may also have automated equipment for de-palletizing and re-palletizing product.
Some of the most sophisticated systems can convey product directly into storage racks and then convey out of the racks to trucks, all automatically.
With a wide variety of product sizes and weights, these systems are designed to handle a specific range of products. Very large, small, heavy, or light products require varying degrees of manual handling.