Susan Lacefield has been working for supply chain publications since 1999. Before joining DC VELOCITY, she was an associate editor for Supply Chain Management Review and wrote for Logistics Management magazine. She holds a master's degree in English.
To the untrained eye, it can be hard to distinguish between a raven and a crow. But birders know that ravens are bigger than crows, have a different call, and sport a wedge-shaped—instead of a fan-shaped—tail.
Similarly, to the untrained eye, one rack can look pretty much like another. But if you hang around distribution centers and warehouses long enough, you know there are many different types of racks and that each boasts unique characteristics.
Just as wildlife guides can help you identify which birds and animals you'd expect to find in which environments, the following field guide to racks can help you distinguish between some of the most common types of manual pallet racks. Ultimately, this information, coupled with a good understanding of your operation, should help you decide which racks are best for you.
SELECTIVE RACK
If you're mentally picturing a rack right now, chances are you're imagining a selective rack. Featuring the most basic of designs—two upright frames and shelf beams placed between them—selective racks are like the pigeons or sparrows of the rack world. Walk into just about any distribution center or warehouse, and you're likely to see selective racking somewhere in the facility.
Selective racking is only one pallet deep, and racks can be placed either against a wall or back to back. In a single bay of selective racking, you can have multiple beam levels, with forklift trucks generally used to place the pallets on the shelf beams.
Selective rack is the most common type, with a very basic designs—two upright frames and shelf beams placed between them.
This type of pallet rack is called "selective rack" because it has a high level of selectivity, meaning that you can access every pallet in the racking system. The drawback is that the system does not provide as high a degree of storage density as other racking systems do.
Selective racks can be either welded or bolted together. The welded (or boltless) design is most popular in the U.S. due to the high cost of labor required to assemble racks on site and concerns around liability if the rack manufacturer is not directly involved in assembly. Bolted designs, however, are preferred when racks are being shipped long distances, particularly overseas.
Benefits:
More economical than other types of rack systems, with the lowest cost per pallet position
Can be easily reconfigured
Provides more selectivity and flexibility than high-density rack systems because pallets are not stored in front of one another
Does not require the use of specialized lift trucks
Applications:
Can be installed in just about any setting/environment and can be adapted to handle products of almost any volume, weight, or size
Well suited to product lines with low turnover and high differentiation
Good for operations with a high stock-keeping unit (SKU) count but low volume
DOUBLE-DEEP RACK
Double-deep racking is created by placing one row of selective rack behind another. The result is racking that's twice as deep as selective racking. In most cases, two pallets with the same product are stored in a slot, and a deep-reach lift truck or a lift truck with a double-deep handling attachment is required to access loads in the rear position.
While double-deep racking looks like selective racking, it is actually considered a type of high-density racking. High-density racking helps users optimize warehouse cube use by allowing more pallets to be stored per cubic foot. However, it is not as flexible as selective racking, and pallets are not as accessible. For example, in a double-deep rack, workers cannot access the rear pallet unless the front pallet position is empty.
Double-deep racking is made up of two rows of selective rack, one behind the other. A deep-reach lift truck or a lift truck with a double-deep handling attachment is needed to access loads in the back rack.
Benefits:
Cost per pallet position is lower than with other high-density options
Increases the productive use of floor space by 60 to 65 percent over selective racking
Applications:
Facilities that require high-density storage
Last-in, first-out inventory operations. Double-deep racking is not as suitable for first-in, first-out inventory management, as that would require double handling of pallets (removing the front pallet in order to access the back pallet)
DRIVE-IN/DRIVE-THROUGH RACK
Drive-in and drive-through racks are a type of high-density racking. They're designed so that lift trucks can enter the rack structure to deposit and retrieve pallets.
Drive-in and drive-through racks represent another type of high-density racking. They are designed so that lift trucks can enter the rack structure to deposit and retrieve pallets. The pallets are stored on rails that run the length of the rack, as opposed to on a shelf beam that's placed between two upright frames. These racks can store pallets two, three, or more deep.
Drive-in racks have one entry/exit point and therefore work well in operations that manage inventory on a last-in, first-out basis. Drive-through racks have an entry point on both sides of the bay and can be used in first-in, first-out inventory operations, as product can be loaded from one aisle and retrieved from the other.
It's important to note that because lift trucks are driven into these racking systems, these racks typically suffer more impacts than other types of racks do.
Benefits:
Requires fewer aisles than selective racking, increasing storage density
While the cost per pallet position is higher than with selective and double-deep racks, it is lower than with other high-density racking systems
Allows you to store up to 75 percent more pallets per square foot than with selective racking
Applications:
Works well for storing similar products on like-sized pallets
Suitable for high-volume SKU storage
Often used for freezer/cooler storage
Good for items that have a long storage life and don't require immediate access
Well suited to storing large quantities of relatively few product types
PUSHBACK RACKS
The rails of pushback pallet racks hold nesting carts that glide along the rails.
In pushback pallet rack systems, the pallet is placed on a series of nesting carts that glide on rails. New pallets are stored by pushing back the previously loaded pallets and placing the new load in the next cart position. Typically, pallets are stored two to six deep. When a pallet is retrieved, the next pallet drops forward into the ready position. As a result, pushback racks operate according to a "last-in, first-out" principle. Pushback racks do not require the use of any type of specialized lift trucks.
With a pushback rack, new pallets are stored by pushing back the pallets that are already there.
Benefits:
Provides similar storage density to drive-in racking's but with better selectivity and accessibility to a range of SKUs
Reduces picking time when a large number of pick faces are required
Provides higher utilization of available pallet positions than most storage systems do
Require fewer aisles than selective racking does
Faster to load or unload than drive-in racks are
Applications:
Operations that have a large number of SKUs and need a lot of pick faces
Bulk storage
Operations that store several products in quantities of more than five pallets per SKU
PALLET FLOW/GRAVITY FLOW
Pallet flow racks help make good use of space; they eliminate aisles.
Pallet flow racks usually feature a metal or nylon stop to keep the pallets in the bay.
In this type of high-density rack, pallet loads are placed at the end of a series of rollers or skate wheels and then flow down an incline to be picked at the opposite end. As a result, they are a first-in, first-out storage solution. Typically, there is a nylon or metal stop at the end to keep the pallets in the bay.
Benefits:
No limit to how deep you can go. Pallet flow racks that are equipped with a brake system have been known to go 20 pallets deep.
Maximizes space by eliminating aisles and storing pallets in lanes
Applications:
Works well in deeper systems
Can be used for pick modules and staging areas
Works well when you have a large volume per SKU
Good for high-throughput operations and for managing perishable and time-sensitive products
This guide has attempted to differentiate among some of the most common types of racking, but it is far from comprehensive. There are many other types of racks that we have not featured here. For example, cantilever racks store long or bulky items such as furniture, lumber, tubing, textiles, and piping. Carton flow racking operates like pallet flow racks but at the carton level. Mobile pallet racking mounts existing pallet racking or shelving on mobile carriages that move with the help of a mechanical-assist handle or an electric-powered system.
WHAT'S BEST FOR YOU?
Developing a basic understanding of the different types of pallet racks is not enough, however. Ultimately, companies need to determine the best rack or mix of rack for their particular operation, and that can be a complex undertaking.
According to Domenick Iellimo, vice president of sales for Frazier Industrial Co., it's important to consider three factors when selecting a pallet rack: the unit to be stored (product load), the method of handling equipment (type of lift truck that you're using), and the area available for storage.
In addition, Dave S. Olson, national sales and marketing manager for the rack maker Ridg-U-Rak, recommends taking at look at what your operation's constraints are. Are you space-constrained? Then you may want to consider a high-density racking solution. Does your operation require that your inventory be managed on a first-in, first-out basis? Then you should know that drive-in or pushback racks won't work for you. How much capital can you invest? If you're looking for the most economical solution, selective racking may be the best choice.
The more informed you are about the different equipment options and the needs of your own facility, the more likely it is that you'll select the right rack for your operation.
Want to know more?
There's a wealth of information available on different types of pallet racks. This article provides only a starting point. Here are a few other resources on racks:
The Rack Manufacturers Institute—one of MHI's industry groups—is always a good place to start for information. The institute's website includes specifications and guidelines as well as a glossary and frequently asked questions.
Many manufacturers offer excellent guides to the different types of pallet racks on their websites. A few used to create this article include "A Guide to Pallet Rack" by Cisco-Eagle, "Storage Rack Selection Guide" by Ridg-U-Rak, and Frazier Industrial Co.'s "Rack 101."
The website of the Australian forklift company Adaptalift Hyster features a Warehouse Racking Guide, a series of blog posts that look at the issue from a forklift user's perspective.
A coalition of truckers is applauding the latest round of $30 million in federal funding to address what they call a “national truck parking crisis,” created when drivers face an imperative to pull over and stop when they cap out their hours of service, yet can seldom find a safe spot for their vehicle.
According to the White House, a total of 44 projects were selected in this round of funding, including projects that improve safety, mobility, and economic competitiveness, constructing major bridges, expanding port capacity, and redesigning interchanges. The money is the latest in a series of large infrastructure investments that have included nearly $12.8 billion in funding through the INFRA and Mega programs for 140 projects across 42 states, Washington D.C., and Puerto Rico. The money funds: 35 bridge projects, 18 port projects, 20 rail projects, and 85 highway improvement projects.
In a statement, the Owner-Operator Independent Drivers Association (OOIDA) said the federal funds would make a big difference in driver safety and transportation networks.
"Lack of safe truck parking has been a top concern of truckers for decades and as a truck driver, I can tell you firsthand that when truckers don’t have a safe place to park, we are put in a no-win situation. We must either continue to drive while fatigued or out of legal driving time, or park in an undesignated and unsafe location like the side of the road or abandoned lot,” OOIDA President Todd Spencer said in a release. “It forces truck drivers to make a choice between safety and following federal Hours-of-Service rules. OOIDA and the 150,000 small business truckers we represent thank Secretary Buttigieg and the Department for their increased focus on resolving an issue that has plagued our industry for decades.”
“While there have been some signs of tightening in consumer spending, September’s numbers show consumers are willing to spend where they see value,” NRF Chief Economist Jack Kleinhenz said in a release. “September sales come amid the recent trend of payroll gains and other positive economic signs. Clearly, consumers continue to carry the economy, and conditions for the retail sector remain favorable as we move into the holiday season.”
The Census Bureau said overall retail sales in September were up 0.4% seasonally adjusted month over month and up 1.7% unadjusted year over year. That compared with increases of 0.1% month over month and 2.2% year over year in August.
Likewise, September’s core retail sales as defined by NRF — based on the Census data but excluding automobile dealers, gasoline stations and restaurants — were up 0.7% seasonally adjusted month over month and up 2.4% unadjusted year over year. NRF is now forecasting that 2024 holiday sales will increase between 2.5% and 3.5% over the same time last year.
Despite those upward trends, consumer resilience isn’t a free pass for retailers to underinvest in their stores by overlooking labor, customer experience tech, or digital transformation, several analysts warned.
"The 2024 holiday season offers more ‘normalcy’ for retailers with inflation cooling. Still, there is no doubt that consumers continue to seek value. Promotions in general will play a larger role in the 2024 holiday season. Retailers are dealing with shrinking shopper loyalties, a larger number of competitors across more channels – and, of course, a more dynamic landscape where prices are shifting more frequently to win over consumers who are looking for great deals,” Matt Pavich, senior director of strategy & innovation at pricing optimization solutions provider Revionics, said in an email.
Nikki Baird, VP of strategy & product at retail technology company Aptos, likewise said that retailers need to keep their focus on improving their value proposition and customer experience. “Retailers aren’t just competing with other retailers when it comes to consumers’ discretionary spending. If consumers feel like the shopping experience isn’t worth their time and effort, they are going to spend their money elsewhere. A trip to Italy, a dinner out, catching the latest Blake Lively and Ryan Reynolds films — there is no shortage of ways that consumers can spend their discretionary dollars,” she said.
Editor's note:This article was revised on October 18 to correct the attribution for a quote to Matt Pavich instead of Nikki Baird.
A real-time business is one that uses trusted, real-time data to enable people and systems to make real-time decisions, Peter Weill, the chairman of MIT’s Center for Information Systems Research (CISR), said at the “IFS Unleashed” show in Orlando.
By adopting that strategy, they gain three major capabilities, he said in a session titled “Becoming a Real-Time Business: Unlocking the Transformative Power of Digital, Data, and AI.” They are:
business model agility without needing a change management program to implement it
seamless digital customer journeys via self-service, automated, or assisted multi-product, multichannel experiences
thoughtful employee experiences enabled by technology empowered teams
And according to Weill, MIT’s studies show that adopting that real-time data stance is not restricted just to digital or tech-native businesses. Rather, it can produce successful results for companies in any sector that are able to apply the approach better than their immediate competitors.
While many companies are launching artificial intelligence (AI) products for use as generic “co-pilots” or consumer-focused gadgets, the Swedish enterprise resource planning (ERP) software vendor IFS says its “Industrial AI” version supports industry-specific processes in “hardcore” sectors based on assets such as power grids, cell phone networks, aircraft maintenance, elevator operation, and construction management.
“Industrial AI is at the very core the solutions we are powering for customers. They are pushing us for ready-to-use AI that they can adopt quickly to solve real industrial challenges like labor shortages, supply chain disruption, [and] stagnated productivity," IFS's Chief Customer Officer, Cathie Hall, said in a release.
In presentations at its user conference in Orlando today, known as "IFS Unleashed," the company said that its latest IFS Cloud 24R2 release supports more than 60 in-depth Industrial AI scenarios. They span generative AI examples like: content generation for training and reports; recommendations for sourcing and suppliers; and contextual knowledge for assembly instruction. The tools also include predictive AI applications like event forecasting; optimization of resources and capacity; and anomaly detection for proactive quality control.
In remarks from the keynote stage, new IFS CEO Mark Moffat—who was appointed to the top office in January—said the company may be less well known than ERP vendors such as SAP, IBM, Oracle, and Infor, but it benefits from a tighter focus on its core users. Instead of selling software across dozens of industries, IFS serves just six industries: aerospace and defense, construction and engineering, energy and utilities, manufacturing, service, and telecommunications.
Thanks to that tight approach, he said the company has earned top Gartner rankings for its software products in field service management (FSM), enterprise asset management (EAM), enterprise resource planning (ERP), and enterprise service management (ESM). And to compound that advantage, Moffat said IFS continues to grow swiftly through acquisition, having bought up a handful of companies in recent months: Assyst, Ultimo, Boka, empowermx, Bolo, Tobin, Merrick, and Copperleaf.
“You need an AI business plan” Moffat told the room. “If you have an AI business plan, that’s terrific, but you can improve it. This area is just moving so fast.”
“ExxonMobil is uniquely placed to understand the biggest opportunities in improving energy supply chains, from more accurate sales and operations planning, increased agility in field operations, effective management of enormous transportation networks and adapting quickly to complex regulatory environments,” John Sicard, Kinaxis CEO, said in a release.
Specifically, Kinaxis and ExxonMobil said they will focus on a supply and demand planning solution for the complicated fuel commodities market which has no industry-wide standard and which relies heavily on spreadsheets and other manual methods. The solution will enable integrated refinery-to-customer planning with timely data for the most accurate supply/demand planning, balancing and signaling.
The benefits of that approach could include automated data visibility, improved inventory management and terminal replenishment, and enhanced supply scenario planning that are expected to enable arbitrage opportunities and decrease supply costs.
And in the chemicals and lubricants space, the companies are developing an advanced planning solution that provides manufacturing and logistics constraints management coupled with scenario modelling and evaluation.
“Last year, we brought together all ExxonMobil supply chain activities and expertise into one centralized organization, creating one of the largest supply chain operations in the world, and through this identified critical solution gaps to enable our businesses to capture additional value,” said Staale Gjervik, supply chain president, ExxonMobil Global Services Company. “Collaborating with Kinaxis, a leading supply chain technology provider, is instrumental in providing solutions for a large and complex business like ours.”