Breaking down the unit load

Regardless of the type of product or the specific industry in question, putting together the perfect unit load is an ongoing quest for many warehouse and distribution center managers. The unit load is integral to the movement of products through the supply chain.

With the increasing emphasis on sustainability, more and more primary packaging designers are looking to eliminate weight and waste at the end of the line, once the materials handling is done. This focus ratchets up the pressure on shippers and handlers to find the magical methodology to protect the load from damage through its journey.

Here, we break down three integral components of the unit load—platform, load containment, and unitization—sharing the advice of experts about how to achieve the best combination of the three to meet the unique demands of your warehouse or distribution center.

The platform: Pallets provide a solid foundation

Nearly 1.2 billion pallets are in circulation in the United States on a daily basis, with wood representing the bulk of them. “For an efficient unit load it would not be economically feasible for this economy to survive without a pallet,” says Bruce Scholnick, president of the National Wooden Pallet and Container Association (NWPCA, 703-519-6104, [url=http://www.palletcentral.com]http://www.palletcentral.com[/url]).

“In countries like China, with an inexpensive and vast labor pool, it has been cost effective to floor load trucks and shipping containers,” Scholnick says. “But here, nearly everything that is boxed or bagged moves on a pallet, making it a critical component of the unit load from a logistics and a product safety perspective.”

In use for the better part of 70 years, wood pallet manufacturers have adapted their construction, repair and recycling processes to meet user demands, including applying methyl bromide or heat treatment—as mandated by the International Phytosanitary Measures (ISPM 15)—to pallets shipped between countries for the elimination of pests, Scholnick says.

Regarding sustainability, not only is wood a renewable resource, but wood pallets are manufactured from waste materials in timber production that would otherwise be destined for landfills, according to Derek Hannum, director of marketing for CHEP (888-243-7111, [url=http://www.chep.com]http://www.chep.com[/url]). Other pallet materials, including reusable plastic and steel pallets, offer environmental benefits from repeated use and recyclability at the end of their useful lives.

“It’s important to consider three things when evaluating your pallet material options,” says Mike Lochner, mid-west region sales manager for Rehrig Pacific (800-421-6244, [url=http://www.rehrigpacific.com]http://www.rehrigpacific.com[/url]). “These are: the characteristics of the load, the operational environment and the distribution channel.”

First, consider your load: its weight, size, stability, primary packaging integrity, and form (boxes, super sack, column load, fluid load). “We see a lot of primary packaging designers trying to design products that both maximize the Grocery Manufacturer’s Association (GMA) standard unit load footprint of 40 x 48 inches and remove weight from the product,” CHEPs’ Hannum says. “This means pallets must have good top deck coverage and good dimensional integrity because the unit load can’t be supported by its primary packaging anymore.”

Next, look at the load’s environment (wet, extreme temperatures, sanitization required, fire retardance requirements) and how it will be used (work-in-progress, rackable storage, transport). Finally, consider your supply chain. All things being equal, wood pallets traditionally cost substantially less than their plastic or steel counterparts, making them ideal for situations where the pallets’ owner is unlikely to get them back.

For plastic pallets, it’s essential to get a return or make sure they never leave your system, notes Norm Kukuk, ORBIS Corporation’s vice president of marketing and product management (800-890-7292, [url=http://www.orbiscorporation.com]http://www.orbiscorporation.com[/url]). “In a controlled loop, plastic pallets offer hygienic advantages over wood. For loads of 3,500 pounds or more, steel pallets in a fully automated handling system make sense.”

Containment beyond cardboard: Reusable containers provide dimensional integrity

In lieu of corrugated boxes, the considerations for using reusable plastic containers (RPCs) are nearly identical to the evaluation of pallet forms. For tightly controlled distribution chains, reusable plastic containers offer sustainability benefits and the dimensional integrity required by automated systems, says ORBIS’ Kukuk.

“Nestable totes with attached lids are perfect for shipping a mixed container load of product in a closed loop,” he says. “They’re returned nested empty inside of one another so you’re not shipping air.” For shipping eaches of multiple products that don’t conform neatly into a stackable, modular load, Kukuk has seen a trend toward placing items in collapsible bulk containers instead of pallets, allowing double- or triple-stacking to maximize trailer utilization.

Purchasing reusable plastic or steel pallets or containers is truly an investment. And the best way to maximize (and ensure) the return is to closely control the asset. A variety of processes to assist with this retrieval—ranging from manual tracking to bar code scanning to radio-frequency identification (RFID) technologies offered in the pooled plastic pallets from iGPS (800-884-0225, [url=http://www.igps.com]http://www.igps.com[/url]) —but it’s most essential for shippers and receivers to work together in partnership to ensure a return, says Rehrig Pacific’s Lochner.

“It’s a top-down commitment to taking a systematic approach to asset management in terms of retrieving and keeping the assets within the system,” he explains. “You also have to continually educate—both internally and with customers—the financial and environmental benefits of applying a reusable container or pallet system to your distribution channel.”

Keeping it all together: Unitization

Far and away, stretch wrap is the most implemented methodology of securing the unit load to its pallet, with 1 billion pallet loads stretch wrapped in the United States (and 2.5 billion worldwide) annually, says Pat Lancaster, chairman of Lantech (800-866-0322, [url=http://www.lantech.com]http://www.lantech.com[/url]).

While anyone can apply multiple layers of thin film around a pallet, the trick to ensuring proper use—that is, securing the load so that it arrives at its final destination intact—is understanding the principle of containment force.

“The total containment force that the film exerts on the load is what holds the load,” Lancaster says. The point is critical, says Lancaster, with ongoing reductions in primary packaging. “There’s a balance between the failure rate of product packaging and the solid waste it causes to the savings resulting from a reduction in the amount of packaging,” he explains.

As a general rule, the more unstable the load, the more containment force required. When the wall thickness of a water bottle is reduced, for example, the containment force needs to be increased dramatically, sometimes two- to three-times, and often with a supplementary technology to prevent that force from crushing the load, Lancaster notes.

“It would be a crying shame if we got 5% of the plastic out of the primary packaging but generated a half a truck of solid waste twice a year by virtue of package failure,” he says. “If you don’t understand containment force you could be shipping product directly to the landfill.”

For enhanced containment of extremely unstable loads, some shippers use plastic or steel strapping in addition to—or instead of—stretch wrap, says Matt Williamson, U.S. sales manager for Wulftec/M.J. Maillis (877-985-3832, [url=http://www.wulftec.com]http://www.wulftec.com[/url]). Determining the best method starts with close examination of the load.

“Is the load going to be on a pallet or not? For example, clay brick is often shipped as a cube with no pallet underneath—the strap alone holds it together,” he notes. Other criteria include how will the product be stacked, does it have sharp edges, what are its weight and dimensions, how will it be shipped, and how far will it travel.

Although both steel and plastic strapping are recyclable, the inherent properties of steel makes it a less ergonomic, and more expensive, choice. The best way to determine the best unitization method and material, says Williamson, is testing via manual application of each to the load in question. “Packaging companies want to earn your business, so they’ll go in and provide that type of testing for free,” he adds.

Educate yourself: Building a better unit load Sampling of seminars at NA 2010*