June 12, 2017 4:00 AM, EDT

Opinion: Optimizing Pallet Flow Performance

This Opinion appears in the June 12 print edition of Transport Topics. Click here to subscribe today.

Operating a warehouse requires management of forklifts, shelving and pallets to make work more efficient and help reduce wait times for truck drivers.

When it comes to pallet racking — a material-handling storage system designed to hold materials loaded on pallets, also known as “skids” — flow storage can help with managing perishable, time-sensitive products on a first-in, first-out basis.


Flow storage is a gravity-driven system by which the pallets sit within the racking on an angled surface, and when the front pallet is removed, the pallets behind it slide forward. This design eliminates the need for aisles and instead fills the space with more pallets. Additionally, forklift travel is greatly reduced because operators need only to place and retrieve loads from either end of the system. Better space utilization also minimizes the need to light, heat and cool the facility, which can decrease expenses.

Still, there are many considerations for those operations looking to implement a flow storage system. The following tips can help with the proper design, selection and operation of the system.

Understanding Flow Storage

• Consider flow storage when efficient storage is critical and space is limited. Flow storage is useful in many applications that include ambient, cooler and freezer environments, raw materials receiving and storage, work-in-process, buffer storage, finished goods and cross-docking. It also is often used to pick module and automatic storage and retrieval systems.

• Understand how flow storage works. Unlike traditional selective rack, a pallet flow storage system has two parts: a static rack structure and dynamic flow rails. The flow rails are set at an incline in the rack structure, which allows loads placed on one end of the rack to move by gravity down to the unloading end. Rollers let the loads move smoothly while self-energized speed controllers act as gentle brakes. As a load is removed, the loads behind it move forward automatically.

Pallet Flow Design Considerations

• Choose a design that can adapt to current and future needs. Because budget and inventory requirements change at both the facility and corporate levels, it is wise to select a flow system with a design that can grow with your business needs.

With flow systems, bays can be added to groups and the bay widths and depths can be expanded to hold additional inventory, which allows you to buy for your current needs and expand later.

• Ensure that the flow storage system has enough rack strength. To be even more accommodating of future needs, such as higher or heavier pallets, select a flow system that provides vertically adjustable beams and ample strength.

You always can reprofile your flow rack to handle higher, heavier pallets if you design for it. Let’s say you use a 48-inch-high pallet today but decide later that a 60-inch-high pallet is more efficient because you want to add two more levels of ice cream to each pallet. A system with vertically adjustable beams would allow you to do it, pro- vided you have the rack strength.

• Ensure that capacity matches capabilities. When you design your flow storage system, you have to know your warehouse’s capabilities and limitations. For example, know how low girders, trusses, warehouse lighting, HVAC ductwork, sprinklers and fire suppression lines hang, and determine how much clearance is required.

Also, before you begin loading the system, it is critical to consult with the local fire marshal and secure approval on the design and layout to ensure it meets fire code regulations.

Safety and Productivity

• Plan for expected flow system use. If your warehouse facility is heavily used, forklift drivers are more prone to hit racking. Because a flow system’s entry uprights tend to receive the most damage from forklift impact, consider working with a vendor that offers a range of reinforced upright options.

• Consider facility requirements and standards. For industries whose products require a high hygienic standard, such as for food, dairy, beverage or pharmaceutical products, it is important to avoid any racking with holes, open spaces or flat spots where food or liquid can accumulate, potentially leading to rot, mold or contamination.

In these cases, to better meet Food and Drug Administration or Department of Agriculture regulations, utilize flow systems that use a sanitary structural channel rack design.

Completing the System

• Seek single-source accountability and get a full pallet test before signing off on the system. Designing and installing a pallet flow system could involve a separate pallet flow manufacturer and a rack manufacturer, as well as a dealer and installer. However, this type of setup is not recommended by experts because of the significant coordination required from each of these independent parties to resolve any issues.

Finally, successful flow systems are the result of proper design and thorough testing of all the related components. The vendor should perform a full test of the system, including rail type, rail pitch and brake spacing, as well as a full pallet test to ensure it fits your pallet, product and workflow.

Steel King Industries, based in Stevens Point, Wis., designs and manufactures warehouse material handling, storage and safety products.