Pallet Racking – Stacking the Benefits

Global commerce today moves at the speed of light – or more aptly, at the speed of need.  Manufacturers produce goods in large quantities that are routed to storage and distribution centers, sitting until a need arises that moves those goods downstream to end users. Balancing this speed of need becomes the daily business of these distribution centers, as they provide the necessary buffer space within the supply chain for the forces of supply and demand to equalize.  One of the that supply chain companies fulfill this role is by utilizing storage systems and workflows that are precisely designed for their exact needs, providing just the right degree of storage volume, inventory accessibility and material velocities for products they’re handling.  For moderate to high-volume distribution, most often this takes the form of engineered pallet racking systems.

In this article, we’ll introduce the most common types of fabricated structural pallet racking designs, their benefits and several key considerations for each type.  To help visualize each design, we encourage readers to check out our photo gallery while you read, found here.

Pallet Racking Types Explained

Below we’ll describe the most common pallet racking types found in material handling, distribution and warehouse applications, along with their primary benefits.

Selective Pallet  

When most folks use the phrase “standard pallet racking,” chances are that they’re referring to single-deep selective racking. As the typical entry point for racked pallet storage, selective racking stores pallets on a modular, stick member frame structure consisting of appropriately sized truss frames, shelf beams and bracing components. These components make up the building blocks for most of the pallet racking solutions mentioned in this article, customized to the geographic location and the desired pallet dimensions, weights and quantities at hand.

There are two variants of Selective Pallet Racking:

• Single Selective – which supports individual pallets per bay, with all pallets being immediately available to pick or ‘select’ by a forklift.  This design best serves high SKU quantities where any pallet must be accessible at any time and offers the lowest initial price point of all pallet racking.
• Double Deep (aka Two-Deep Reach) Selective – which supports one pallet behind the other, with the front pallet being immediately available to pick from the forklift aisle, and the back pallet being accessible only after removing the front pallet. This design better utilizes warehouse space by reducing the number of forklift aisles needed to access inventory, in exchange for slightly higher upfront costs and potentially slower pick times shuffling pallets.  Also, a reach-type forklift is needed to pick the rear pallet position.

Pallet Racking

Building upon the concept of double-deep racking mentioned above; uses deeper lanes to store multiple pallets in a row with only the front pallet being accessible to the forklift aisle. In addition, push back racking uses movable carts to carry pallets back into their rows. In an empty row, a forklift places the first pallet into the rack right at the aisle face, setting it on a cart instead of static rails (like with selective racking).  A second pallet is brought over, and as it’s set into the rack; same as the first pallet, it ‘pushes back’ the first pallet on its cart.  This process repeats up to the depth of the pallet lane, which can be between 2 and 7 pallets deep. When a pallet is removed from the front position, the pallets and carts behind will roll forward by gravity, bringing the next pallet to the aisle or front position automatically.

The concept of ‘deep lane’ storage is imperative in high-volume warehouse design, as we see introduced with push back racking. This concept applies to all the below racking options as well.  Overall, this design maximizes floor space utilization while keeping the forklift interface at the aisle, allowing for more pallet area and less forklift aisle area for a given warehouse.

We’ll introduce one more term related to push back racking – FILO LIFO inventory access, meaning First-In, Last-Out Last In, First Out. With push-back racking, the first pallet set into a row is pushed all the way to the back of the lane, making it the ‘last out’ when the lane is picked.

Drive-In Pallet Racking 

Where the above push back racking design utilizes carts to nest pallets behind each other into deep lanes, Drive-In Pallet Racking uses the forklift itself to place pallets into position. On the upside, drive-in racking is less complicated and less expensive upfront than push back racking, consisting simply of pallet rails and structural frames. On the downside, drive-in racking tends to cost more to maintain over time and is often not configured as deep as other deep lane solutions; due to driving a forklift physically into deep lanes results in more damage from impacts and wear and tear.

When considering drive-in racking, imagine the operating conditions in play. Operators must drive in and then back out of a potentially 25-foot-long lane, with a load up at high elevation based on stack height, in a very straight line without hitting the rack structure.  Pallet movement must generally start top to bottom, such that you need the bottom lane filled last so that the forklift has space to drive. In addition, managing SKU distribution in drive-in racking can be challenging if you have too many mixed lanes. This requires multiple pallet shuffles to gain access to buried SKUs. Lastly, forklift compatibility is very important – narrow-aisle reach lifts with minimal outrigger lengths tend to be great selections, as you can use the reach accessory to reduce how deep the lift itself must go into a lane.  For these reasons, drive-in racking tends to be ideal for lower SKU count, lower-velocity, smaller module scale (such as 4 pallets deep by 3 layers high), FILO inventory warehouses.

Drive-Thru Pallet Racking  

In short, Drive-Thru Pallet Racking is a variant of the above drive-in pallet racking that allows for access on both aisle faces of the pallet lanes, not just one. This feature allows for FIFO inventory management, or First-In, First-Out. As with drive-in racking, a forklift will enter one side of the rack and place the first pallet all the way at the far end, followed by subsequent pallets until the lane is full (again filling top level to bottom). Here now, another forklift can approach the opposite face of the rack and concurrently pick the first pallet put in by the first forklift, continuing to unload while filling continues by the first lift. Drive-thru racking opens many opportunities for simultaneous loading and unloading, both FIFO and FILO LIFO inventory schemes, safer traffic separation, and faster overall inventory turns all in a single racking system.

With the added activity comes added risk of impact-driven issues, of course. Drive-thru systems should be heavily evaluated for structural reinforcement, secondary protection, and more frequent maintenance to offer a long and safe working lifespan.

Pallet Flow Racking

Pallet Flow Racking utilizes  deep lanes equipped with gravity roller rails that mechanically convey a pallet from one end of the lane to the other.  Forklifts will set incoming pallets on one end of the rack, which will roll down to the opposite end ready for pick-up by another forklift immediately. Since forklifts do not have to drive into the racks here, impact risks are minimized and flexibility maximized by keeping forklift interactions to the aisle faces while the racking itself handles rolling pallets into position.

Pallet flow racking provides FIFO inventory management exclusively and may take moderate maintenance over time to keep rollers in good condition. But, when properly designed to the pallet weights and configurations expected and when pallet quality is well controlled, pallet flow racking can provide beneficial and high velocity storage solution short of introducing warehouse automation.

Rack Builders, Inc is the United States’ premiere industrial Storage Racking Engineering and Manufacturing company, driven by our core values of Ingenuity, Quality, Integrity and People.  With Turn-Key capabilities from concept design through installation, our Quincy, IL based team directly serves domestic and international contractors, builders, integrators, distributors, and end-users alike. Our 200,000 sq ft manufacturing facility and certified fabricators produce custom racking solutions that have earned us accolades including MHEDA Most Valuable Supplier award and MHI’s prestigious R-Mark.  We look forward to hearing about your next racking project!  Reach us at (847)-330-1724 or online at https://www.rackbuildersinc.com/.