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Big Picture: A new take on unit-load storage

As end users optimize their facilities, high-density dynamic storage is getting a fresh look.
By Bob Trebilcock, Executive Editor
December 01, 2012

If you attended the Modex show last February, you may have seen demonstrations of new unit-load storage technologies at booths sponsored by Power Automation Systems (PAS) and the Italian company Smoov.

Both companies were highlighting solutions that combine deep-lane storage rack with automatic carts or shuttles that move pallets to and from storage. They weren’t alone. Frazier Industrial was also exhibiting its semi-automated shuttle technology for pallet storage.

If you missed them, you’re not alone. For the last couple of years, automatic guided vehicles (AGVs) and mobile robots have been getting a tremendous amount of attention. Less noticed have been the innovations around pallet-handling storage technologies.

Look closely, however, and you’ll find technologies that fill the gap between conventional deep-lane pallet storage and a fully automated unit-load automated storage and retrieval system (AS/RS). Within the industry, these solutions are referred to as high-density dynamic storage. These solutions aren’t right for every application, or even every pallet handling and storage application; however, for facilities that have already gathered the low-hanging fruit, they may be the next level of improvement. 

These solutions also illustrate a way to think about storage. In many instances, storage is no longer simply a process unto itself. In fact, conventional reserve storage is set apart from modern supply chains designed to keep product in motion as much as possible.

Instead, as the term “dynamic” suggests, storage is becoming an integral component of other processes, such as manufacturing work-in-process, order fulfillment and shipping. Applied dynamically, storage becomes a tool that facilitates even faster movement of product through a facility. The best solutions minimize the space and labor devoted to storage as well as reduce the length of time a product remains at rest.

In this Big Picture, we’ll look at what’s behind this emerging area of unit-load storage and how the technologies are being applied.

What’s in a name?
The concept behind high-density dynamic storage isn’t new. Rack companies such as Interlake Mecalux, Frazier Industrial, Konstant and LoadBank— a solution now marketed by SafeFlo Technologies—have offered some type of high-density dynamic storage for years.

What differentiated these early solutions from conventional deep-lane pallet rack was the movement of the pallets within the rack—the dynamic part—so that a lift truck didn’t have to enter the rack system to store or retrieve a load. The idea was to improve productivity and reduce damage to the racks because a lift truck operator wouldn’t have to slow down to safely handle pallets deep in a lane.

What differentiated them from an AS/RS was the degree of automation: Regardless of the solution, they were designed to interface with a lift truck rather than operate autonomously like an AS/RS.
These largely niche solutions were used by manufacturers that needed to store a large number of pallets of a limited number of SKUs. More importantly, they didn’t need to go 60 or more feet high to justify the cost of implementation as is the case with a full-blown AS/RS. For those reasons, the primary competition was conventional rack. 

If the technology has been around so long, what’s changed? And, why are end users taking a harder look now? The simple answer is the increasing complexity of the supply chain: As end users push more and more requirements upstream, manufacturers and distributors need to meet those demands while still controlling costs.

“The analytics that our customers are deploying to understand their product mix and velocity is allowing them to be more refined about how they manage their SKUs,” says Dan Garside, general manager of Frazier Industrial’s Canadian operations. “That’s bringing a better appreciation for these unique systems.”

The systems allow shippers to isolate the ideal mix of SKUs and improve selectivity in a high-density environment. “A dynamic storage system allows you to get between 80% and 90% occupancy compared to about 60% occupancy in a conventional drive-in rack system,” says Garside. “That basically means you can reduce the amount of space you need for storage by about 30% for the same number of pallet positions and possibly use fewer lift trucks.” At the same time, he adds, productivity is improved because a pallet is always at an aisle and ready for pickup.

These solutions work especially well in operating environments where manufacturers are managing smaller levels of inventory per SKU, managing an increasing number of SKUs or making smaller and more frequent shipments, says Elisabet Fasano, brand marketing manager for Smoov ASRV S.r.l. “AS/RS technology can achieve high throughput and fast response times when the throughput is high and stable,” Fasano says. “But the design is rigid and cannot easily adapt to rapid changes in demand. Shuttle-based systems can be quickly and easily expanded to add more vehicles to support rapid growth or peak seasonal fluctuations.”

In addition to complexity, at least four other factors are influencing the interest in high-density storage.

  • The next level of optimization: Manufacturers have historically focused on building higher speed production lines to bring down their manufacturing costs. Now, they are being asked to do more with their distribution systems. “They can no longer rely on bulk storage on the floor,” says Fred Grafe, president of operations and sales for PAS Americas. “They have to reduce their supply chain costs.”

  • New packaging that won’t stack: The beverage industry, in particular, is looking at high-density storage as an alternative to floor stacking. “With new packaging designs, you can’t stack a pallet of PET bottles on top of another pallet of PET bottles,” says Tom Coyne, CEO of System Logistics. “Coming off the production line, you need an efficient way to store product.”

  • Retrofitting an existing building: Most end users would rather retrofit an existing building than build a new site, says Dan Quinn, president of SafeFlo Technologies. Some of that is being driven by green initiatives. Some is simple economics: High-density dynamic storage allows an end user to make use of the total cube in an existing building. Quinn adds that these solutions can also be configured to conform to the shape of the building or to work around structural supports. “If you need to make it L-shaped, you can make it L-shaped,” says Quinn.

  • Remove employees from a hostile operating environment: No one wants to work in a freezer or refrigerated warehouse space. What’s more, those spaces are expensive to operate. “The fuller you can fill a freezer, the lower the utility cost,” says Steven Beyer, director of business development for Retrotech. “With a high-density dynamic solution, you increase the storage density and there is no more need for a labor force that constantly requires warm up breaks.”

Regardless of the product or industry, the applications where high-density dynamic storage works best are manufacturing or distribution environments where product turns are measured by days or weeks instead of months.

“For many of the users we’re talking to, storage is taking on dimensions beyond just putting things away and then retrieving them when they’re needed,” says Beyer. “It’s a more active, dynamic and multi-faceted component of the supply chain.”


HD/DS definition

More than a decade ago, the Material Handling Industry of America (MHIA) created a definition for the space:
“We define HD/DS (high-density dynamic storage) as a concept where multiple unit loads of the same SKU are sequentially stored in the same location or lane, (one in front of the other), with a minimum distance between loads, thus the item high density. The term dynamic storage implies moving storage, because a HD/DS system also has the ability to automatically or semi-automatically index or convey the loads from the load point to the unload point of the system. More realistically, [high-density dynamic storage] is a flow through rack, where loads pass through the rack toward their next point of use, as preceding loads are used or retrieved.”

About the Author

Bob Trebilcock
Executive Editor

Bob Trebilcock, executive editor, has covered materials handling, technology and supply chain topics for Modern Materials Handling since 1984. More recently, Trebilcock became editorial director of Supply Chain Management Review. A graduate of Bowling Green State University, Trebilcock lives in Keene, NH. He can be reached at 603-357-0484.


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