The Traditional Order Pick System is used by many distributors today. In this system, pallets of product are taken from the dock, where they have arrived from the producer, and are placed in racking slots. Selectors then remove a specified amount of product from the slots and place them on pallets so they can build loads of goods as per customer specification. The selector moves the pallet from slot to slot collecting the specified goods using some sort of lift and transport device. Generally, this device is a pallet jack but in some warehouse operations a fork lift may be used. The pallet jack is often capable of carrying two pallets at a time and the selector can sometimes ride on the device from slot to slot. After a palletized load is fully assembled, it is wrapped with a plastic material and loaded into a truck for delivery to the customer's facility.

The advantages of this type of system are that it allows tremendous amounts of product to be stored in reduced floor space since much of the product is stored in overhead slots. Product handling is minimized since it is lifted only once from the slot to the destination pallet. Product is moved using a pallet and mechanical means for most of the operation. Large orders can be filled as full pallets with little manual lifting. Employees are also provided frequent micro-breaks as they move from one slot to another.

The disadvantages of this system are that Selectors are exposed to a number of musculoskeletal stresses including heavy lifting, bending, reaching, twisting, etc. Because employees move about the warehouse, development of mechanical aids to assist with heavy lifting or reducing awkward postures is difficult.

In a flow through system, product is received at an in-bound dock, broken down, and placed on a conveyor system. The product is coded immediately after arrival and moved via conveyor to a sorting area where it is sent to the appropriate out-bound truck for shipping. Product is not stored or palletized during this process.

The advantage of this system is that there is reduced handling of product. This is especially true if a full pallet is requested but is also true when loads are broken down since this function can be done at a single specified site where the use of lifting aids and other mechanical equipment is more feasible.

The principle disadvantage of this system is that it is very floor space intensive and it involves an extreme degree of coordination to get all product to the right place at the right time.

In a belt pick system, pallets of product are taken from the dock and placed on a belt or in racking slots. Selectors then remove a specified amount of product, as per customer order, from the slots and place it on a conveyor belt that runs down the center of the slot aisle.

Product from each aisle comes to a central area where the product is removed from the belt and placed on a pallet. After a palletized load is fully assembled, it is usually wrapped with a plastic material and loaded into a truck for delivery to the customers facility.

Some advantages of this system are that sincethe employee works at a defined space the use of lift devices and assists is more practical. Hoistsor lift assists can be placed along the line to help employees. The height of the receiving conveyor can be maintained at a level which minimizes bending and elevated reaches. The final palletizing station can be designed in a manner to eliminate torso bending and elevated reaches by using platforms, turntables and lifts. Fixed workstation positions allow lift-assist devices to be mounted at these stations.

This system has its disadvantages in that all product must be handled at least twice instead of once. One employee pulls the product and places it on the belt, while another must lift it from the belt to the destination pallet. The frequency of lifting may be much higher since large orders must be placed on the belt one case at a time instead of moving them as a unit on the pallet with a mechanical device. Employees also miss out on the micro-breaks inherent in the traditional order pick system as there is no travel time between work areas.

In a cross-docking system, pallets of material are received on one dock, broken down into customer specified loads while still on the dock and transferred to outbound trucks. Items are not placed in slots for storage.

A cross-docking system offers the advantage that product is generally shipped in larger quantity which minimizes the lifting of single units of product.Larger quantities are usually moved via mechanical means such as forklifts with little individual manual handling. If pallets must be broken down into smaller units, this can be performed without the confines of storage racking. This facilitates the use of lifts and other mechanical means and increases the access of employees to product.

This type of system is not practical for many grocery distribution warehouses. Their customers generally do not deal in full pallet orders and the diversity of product requires more floor space than is practical. This system also requires a high level of coordination of incoming and outgoing product.