On the surface, pallet storage in your warehouse seems straightforward. Pallet loads come for placement into storage until the need requires you to prepare it for shipment. However, once you drill down based upon the many factors, you notice something far more complex.
Pallet loads contain a variety of products from bags of peanuts to transmissions and everything in between. Some are time sensitive while others can sit in storage for long periods. Each load requires special consideration for storage.
This is why the material handling industry offers so many storage variations. We will cover several from the very simple to the extremely complex. Then, we will also cover the varying types of lift equipment because racks and lift trucks must be compatible.
Just Stack It
Not every storage solution requires row after row of pallet racks. It is possible to create rows of product using nothing more than the pallet and the load on the pallet.
This is known as stacking. Stacking, where products are stacked on top of each other on the warehouse floor, is an option for some applications. Two key factors are required—rigid products able to cube out a load and pallets in very good condition.
Beverages or canned products typically benefit from stacking. The turnover of these products often is very quick so there isn’t a great need for elaborate racking.
Stacking has its limitations.
Available floor space is crucial for successful stacking operations and the depth of stacked lanes should not exceed four or five pallets deep. The number of pallets stacked typically is around three high because more weight could crush products on the bottom pallet.
This can be inefficient in many operations. Loads not having a cube shape are unstable and risk falling or making retrieving pallets difficult, adding labor to load and unload a pallet (if in poor condition).
A variation of stacking still uses pallets as the basis for stacking but also includes a wooden frame that connects to the pallets. A metal (steel) frame with decking is another variation. These are very portable units and work well in certain circumstances such as overflow or short-term storage.
The benefits of stacking frames are that it takes simple pallet stacking to the next level. These essentially create storage racks using the pallet as part of the rack structure.
This method of stacking can support several thousand pounds of weight and even provide some stabilization for unsecured loads. The frames assemble and disassemble quickly.
However, this is not a long-term storage solution and is better for settings where there is not enough floor space to accommodate all the pallets.
The frames allow for safe pallet stacking – about four high. Again, this is a viable short-term storage option, but not recommended for long-term for many reasons including safety.
Selective racks are by far the most common rack option, mainly because of the many variations available. However, these variations still are ruled by certain restrictions.
Most selective racks allow one, maybe two pallets deep. This is beneficial in providing easy access to products that turn over quickly and offers easy access to a variety of SKUs.
No special equipment is needed to load or unload from these racks.
Applications for using selective racking tend to work better in smaller operations that do not deal in high volume. Warehouses with high-density storage needs are not a good fit, as selective racking requires too much floor space to function properly.
Loading/unloading would also take more time and be less productive. These racks are not recommended for vertical storage needs. The maximum height for these racks should not exceed 40 feet.
Warehouses and distribution centers involved in high volume operations value the speed and flexibility offered by drive-in or drive-through racks.
These racks can be configured to accept last in, first out (LIFO) or first in, first out (FIFO) loading applications making it ideal working with high volumes of few SKUs. It provides exceptional control of product input and output.
Product may be loaded for storage on one side and retrieved for shipping on the other, reducing the amount of traffic in the aisles. And because the design of these racks use gravity, no additional maneuvering by forklift drivers is required to access each pallet.
This type of rack also reduces the potential for damage, keeping repair costs low.
Drive-in/drive-through racks are designed for vertical storage and are limited only by ceiling height and the equipment placing or retrieving it. The effectiveness of this type of rack is affected by the quality of pallets used.
Broken pallets or pallets in less than optimal condition can and will affect the ability to store and retrieve, causing delays and potentially affect the safety of workers.
These racking products offer improved pallet storage options. These racks work very well in warehouses that turn over product with medium to high levels of frequency.
Most applications can use these rack products as is, however, certain applications require modifications to fit the specific needs of products (including shelf life) and pallet type.
Pushback and pallet flow racks are two examples of dynamic racking systems. Both rack systems have the capabilities required for high volume warehouse applications.
Pushback rack uses a cart system on which the pallets rest. The carts are nested so as a new pallet is loaded, a new cart becomes available when the pallet being loaded pushes back the previous load. It works well in settings where product volume turns over quickly.
This pallet system generally functions in LIFO configurations however, FIFO operation is possible when configured correctly. Care is required when unloading pushback racks as forklift serves as the brake for the pallets in the rack.
Unloading too quickly can cause the remaining pallets to move forward quickly, creating the possibility of damage to pallets or injury to workers.
Pallet flow racks are a favorite of most forklift operators. Operators frequently rank these racks among the easiest to work with and maneuver around.
Warehouse owners also like pallet flow racks because of productivity gains these racks offer with a FIFO configuration. Pallet flow racks work very well in high volume operations and particularly in warehouses used for time-sensitive products such as food and frozen products.
These racks improve safety in the aisles as loading is done in the aisle behind the rack. This rack uses gravity to move pallets forward to the next aisle where unloading occurs. Many consider this rack system one of, if not the most efficient.
Cantilever rack is somewhat unique in material handling based on appearance and function. Its design features a main counterbalanced vertical beam in the back with arms extending from the main beam on which the products rest.
Products best suited for these racks are those that are long, non-palletized and non-standard shaped, such as pipe or furniture.
Automated Storage and Retrieval Systems (AS/RS)
One typically sees an AS/RS unit in very large distribution centers dealing with the highest volume of products. Most automated storage and retrieval systems are designed to maximize vertical storage and minimize the footprint required for the facility.
This automated type of system includes cranes, shuttles, carousels (horizontal and vertical), AS/RS rack-supported buildings and more. The software that controls this type of equipment is oftentimes just as important as the equipment itself.
While AS/RS systems are configurable, the high cost often makes using such a system for smaller applications too expensive.
Equipment to Load/Unload
When it comes to types of equipment for loading or unloading products in warehouses, most people think of the standard forklift. Also called a counterbalance lift truck, the forklift is a labor-saving device for moving product to and from storage and ultimately to the loading dock.
However, there are many more options ranging from very simple to extremely complex to handle this function.
The simplest piece of equipment is a pallet jack. The pallet jack has two forks that slide under a pallet and then lift the product from the floor using a hydraulic jack. Once lifted, a person guides it to the desired location.
You see pallet jacks used in facilities that store products on the warehouse floor, where stacking is used extensively.
A straddle truck or sideloading truck is used in warehouses having narrow aisles. These vehicles work exclusively in the aisle to load or unload pallets and deliver the pallets to the end of the aisle, where a standard forklift comes and takes the pallet to the desired location.
Turret trucks are found in very narrow aisle applications. The forks on these trucks can rotate 180 degrees, making it ideal for working in very narrow aisles. It has the capability of retrieving and storing products at a height of up to 40 feet.
These trucks depend on a wire guidance system on the aisle floor to keep the truck straight for safety.
Selecting the Correct Rack and Truck
What rack system works best for your application?
As you can see, the options are very diverse and making such a selection requires a total understanding of your needs and goals. Making such a selection without input from professionals who understand the gamut of options can result in costly mistakes.