There is little doubt that warehouse racking is an effective means to make maximum use of available storage space. However, it is also a product that comes in a variety of forms, each with its own purpose. Before making a choice, therefore, it will be necessary to consider a number of points. The height of the premises and how much floorspace is available should probably be one of the first considerations, together with the number, sizes, and types of pallets in use and how often they will need to be accessed.
Equally important will be the number of different stock-keeping units held and whether they have a shelf life, as this will affect the choice between FIFO and LIFO systems. In addition, the appropriate choice of warehouse racking will be influenced by the type and lift height of the forklifts to be used. Inevitably, of course, any choice must also be based on the available budget.
Where a company’s finances may be limited, selective pallet racks could be the most economical choice. In addition to its low cost, this type of installation offers easy access to all pallets and is also suitable for either FIFO or LIFO systems. On the downside, however, the use of selective pallet racks tends to limit storage density due to the need for aisles between the rows.
The size and shape of items to be stored can also have an influence on the choice of warehouse racking. For example, if it is required to store long items such as plastic or metal tubing, lengths of timber, rolls of carpeting, or bolts of fabric, the use of cantilever racks with their long arms and absence of shelving provides easy access for a forklift to pick or place stored items directly.
Where it is necessary to maintain a high storage density, either due to heavy demand or limited floorspace, drive-in and drive-through installations can be viable options. Rather than using crossbeams to store pallets, this type of warehouse racking consists of side rails supported by rigid uprights. This arrangement allows a forklift to drive directly into a bay. The drive-in version has an entrance at one end only and is designed for LIFO operation while an entrance at each end of the drive-through installation renders it suitable for FIFO operation.
While a depth of six to eight pallets per bay is fairly typical of these systems, and might be sufficient in many cases, pallet-flow racks are designed to accommodate a depth of up to 20 pallets or more and thus provide even greater storage density where needed. In these FIFO units, a built-in roller conveyor is pitched sufficiently to allow the action of gravity to propel pallets loaded from the back to the front of the system for picking.
For a LIFO operation, pushback racks operate on a similar principle, except that both loading and unloading are performed at the lower or exit end of the system. To operate with this type of warehouse racking, an incoming pallet must be used to push back any pallet that is occupying the exit position in order to take its place. While flow racks only require one aisle, their limit is four to five lanes deep.