Pallet racking was first widely used during and immediately following World War II to meet demands for greater storage density. The shelving used in warehouses prior to the war could not accommodate the massive industrial activity and supply chain needs of the war effort. Since that time, pallet racking has been used by businesses as a key part of their warehouse storage operations, and its use has expanded greatly. It’s now a staple of almost any businesses that store large volumes of physical inventory. Pallet racks can also be used in non-warehouse applications for miscellaneous storage needs.
Pallet racks offer several storage advantages. The most significant of these is that racking offers greater storage density, which translates into overall better use of available space. In warehousing, space is money. While warehouse storage racks require an investment on the front end, they usually offer a positive return on investment by allowing the storage and throughput of more product. Pallet racking can also be considered an organizational tool for warehouses, directing the flow of traffic and inventory in a way that’s efficient and keeps errors to a minimum. Not every aspect of every type of pallet rack system is advantageous. For example, some types of racking may lack density compared to other types, and some may be denser than others. In the aggregate, however, having pallet racks in your warehouse means having greater storage density and selectivity than if there were no racks at all.
Selective Pallet Rack – Manufacturing
There are two types of steel used in the manufacturing of pallet rack components: roll formed steel and structural steel. Roll formed steel is manufactured by feeding a strip of steel through mounted wheels that bend the steel into the shape desired. In the case of pallet racking, the strips of steel are bent into the shape of the upright frame column or lacing channels, or the rectangular shape of the cross beam. Roll formed steel is ideal for the manufacture of pallet rack because it is well suited for producing large quantities of lengthy products. Roll forming also allows for flexibility, as the only limit to the length of product manufactured is the length of the steel being fed into the steel roller. Roll formed steel becomes stronger as more bends are added to the structure of the product.
Unlike roll formed steel, which is manufactured in a cold state, structural steel is cast in a mold while in a molten state. Once the beam is cooled, it will be passed through rollers that tweak the shape of the beam to its exact desired state. Structural steel forms the “I-Beams” many are familiar with, and is a staple in the construction of many commercial buildings. Structural steel is considerably stronger and more durable than roll formed steel, but also more expensive. When used in pallet racks, it is ideal for heavy-duty applications where the required capacities are stronger than average.
In addition to the difference in steel manufacturing, pallet shelving is also made with a variety of different punch hole types. In an upright frame, the punch hole is the slot in which the pin located on the end (or “ear”) of the cross beam locks into. The punch hole and beam ear form the beam-to-frame connection. Over the decades, a wide variety of beam-to-frame connections have been manufactured, often used by rack manufacturers as proprietary designs. Today, the most widely used design is the “teardrop” punch hole, which features a wide opening at the top that tapers smaller at the bottom, holding the beam pin in place with the help of gravity. There are large number of teardrop-style pallet racking manufacturers, and the majority of their products are compatible with one another. Thus, teardrop rack has become the industry norm. However, while teardrop is by far the most popular, there are still several other punch-hole types manufactured. Many of these styles are proprietary but some, like teardrop, are generic.
Warehouse Shelving Dimensions
Before obtaining new pallet rack, users must determine the dimensions needed. Each pallet shelving component — upright frame, beam, and wire deck — has its own specific means of measurement.
Upright frames are measured in terms of depth, height and column dimensions. Frame depth is calculated by measuring the distance from the outside of one upright column to the outside of the other upright column. The depth needed for a given application is figured by taking the depth of the pallets that will be used and subtracting 8”. The 8” is subtracted in order to allow the pallet edge to overhang the pallet rack beams by 4” on either side. This provides optimal support for the pallet, while simultaneously allowing for a bit of room for error when loading and unloading.
Another important pallet rack dimension to consider is the beam face height. Beam face height is a predictor of beam capacity, i.e. the lower the beam face height, the lower the capacity — and vice-versa. Beam face height measurement is taken by measuring the vertical distance between the top edge of the beam and the bottom edge when the beam is sitting in a horizontal position.
Wire decks are simply measured in a depth x width measurement. The depth of wire decks is measured the same way as the depth of upright frames — from one outside edge to the other. If a wire deck is waterfall-style, meaning it drapes over the top of the beams when in place, the depth measurements of the frame and wire deck should be the same. If a wire deck is drop-in style, meaning it sits flush with the top of the beam level and sits atop the beam step, then the beam depth should be equal to the depth of the frame minus the width of the top of the beam. Wire deck width is the remaining measurement, and is dependent upon the length of the beam. When calculating the ideal wire deck depth, the aim should be to use whichever number of decks and combination of wire deck widths will come closest to covering the entirety of the beam level. Often, 2 or 3 decks of the same dimensions will be used to cover a beam level, but instances of needing to use two decks of differing dimensions or a single deck with the correct dimensions to cover a beam level are not uncommon.