Corrugated: The Road Most Traveled

Corrugated has long been the material of choice for containers. It still leads (in amount used) all other material for product protection. According to information from the Pulp and Paper Products Council (PPPC), North American containerboard production increased by four percent in February, an overall increase of about three percent from the previous year.

The increase, says the PPPC, is nearly all attributed to virgin fiber grades. These grades account for about 70 percent of total containerboard. The association also reports that boxboard production was up seven percent over last year’s numbers.

At the same time, after some slow-growth years, carton sales are beginning to show some improvement as well. The National Paperbox Association (NPA) reports carton sales were up 2.57 percent while rigid box sales were down 3.2 percent for the first couple of months this year. Billed carton sales were $78.5 million in the January-February time frame.

According to the Paperboard Packaging Council’s (PPC) Trends 2002 Industry Outlook and Market Data Report, folding carton shipments in the U.S. are forecast to grow about 1.8 percent through 2004.

A wide variety of issues are forcing companies to explore alternate material and ways of transporting products, particularly if the shipments are headed overseas. Pallets and containers of engineered wood, plastic, metal and various configurations of all of the above are available. The corrugated box has been the preferred shipping container for a century with good reasons.

The plain, old cardboard box is anything but. The ubiquitous box is actually made from a high-tech, engineered material. The vast majority of corrugated products are designed and prototyped with advanced, computer-aided design and manufacturing systems. Corrugated cartons are reusable and recyclable.

Toward a common footprint

The Fibre Box Association (FBA), working with other associations such as the European Federation of Corrugated Board Manufacturers and the International Corrugated Case Association Inc., has created what it terms the common footprint standard.

Because the shipment of produce is international, the association developed this standard, which establishes length and width dimensions, and interlocking stacking features for corrugated containers to facilitate efficient loading, handling, storage and shipment on standardized pallets.

The common footprint standard applies to corrugated containers used to ship produce from the growing or initial packaging location to a retail location, usually through a distribution center, and includes containers that are designed to display produce at retail locations.

This voluntary standard establishes industry compatibility and provides a uniform platform for ongoing design creativity to satisfy individual customer marketing and distribution needs.

One area the footprint standard does not address is strength values. The wording of the standard informs manufacturers of their responsibility to incorporate container strength appropriate to the application and commodity. It does not give specific burst and compression stacking strength value recommendations. These are functions of the weight of the container contents and fiber content of the corrugated, in addition to container design features not necessarily covered by the standard.

The standard encourages container manufacturers to use corrugated’s inherent design flexibility to ensure that produce is packed in containers that suit each commodity’s need.

Containers designed using the standard can be stacked on GMA industry-standard pallets (48 in. x 40 in., or 1200 mm x 1000 mm) without overhang. The containers can be stacked in stable mixed loads with other shipper’s goods, also packed in standard footprint containers.

Optional things like handholds and covers are allowed within the design of containers. When designed by the standard, containers will not nest into the container below when stacked.

More information about the common footprint standard is available at FBA’s Web site, www.fibrebox.org.

Corrugated pallets

Two years ago, John W. Clarke, Marshall S. White and Ralph L. Rupert, at the Center for Unit Load Design, Virginia Tech, did a performance study on 48 x 40 in. corrugated pallets. The pallets tested were a patented design from Packaging Unlimited, Louisville, Kentucky.

The conclusions of the tests were that skid-designs with stringers that contained two hardboard strands were not stronger than samples with one hardboard strand. Designs with three hardboard strands were 30 percent to 33 percent stronger than the equivalent designs with one strand.

The three-stringer, three-strand skids were stronger than the four-stringer skids with one or two strands. Skids manufactured of stringers with a more recyclable hardboard grade were stronger than the regular hardboard grade for three of the four designs tested.

The type of load may govern rackability more than design. There was a 20 percent to 30 percent difference in strength between the four-stringer, three-strand skids and the three-stringer, three-strand skids when supporting the same load. There was an 85 percent to 100 percent difference between these same designs when supporting different loads.

Performance and functionality of these designs will vary depending on environmental conditions, load rigidity and equipment interfaces. The researchers recommend users field test samples of these pallet designs before full-scale implementation.

Improved Material Improves Performance

Distance Packaging is a business of F.X. Coughlin Company, an Exel Company, focusing on design and integration of highly customized supply chain packaging for the automotive sector. In the mid-1990s, the company was called to design a packaging system that could maximize cube use in ocean containers for delivering automotive parts just-in-time to a U.K. automotive assembly plant.

At the core of the packaging program is a pallet box that rests on blocks to facilitate handling. Recently, a new product from Pactiv Corporation — HexaBlok blocks was brought to Distance Packaging’s attention. When the pallet box was first designed, the company used built up, corrugated-wrapped pallet blocks. The second generation of blocks were C-flute corrugated, wrapped around Hexacomb honeycomb. The current variation is an all-honeycomb block construction.

Sean Kelly, director of technical sales and engineering service, Distance Packaging, says the pallet box consists of a honeycomb pallet from Pactiv and a sleeve of either double-wall (500-pound) or triple-wall (1,000-pound) corrugated, accompanied by top (275-pound single wall) and bottom corrugated trays (350-pound or 500-pound double wall).

In use, the pallet rests inside the bottom tray. (The tray has been die-cut to accept lift truck forks.) Two U-shaped corrugated pieces are used to construct the sleeve. The pieces slide into a channel created by the gap between the bottom tray and the pallet. A top tray friction-fits over the sleeve, holding the components together.

Five different pallet footprints, ranging from (outside dimensions) 44 x 38 x 22 inches to 88 x 58.5 x 44 inches, are used to accommodate more than 75 different part numbers.

“Our challenge,” says Kelly, “was to come with an all-paper based packaging structure that was 100 percent recyclable. Wood just wasn’t an option because of the recycling challenges — particularly in European countries.”

HexaBlok blocks are lighter, cleaner and more cost-effective than other block alternatives, he adds. Additionally, they provide adequate strength to transport containers which range from 200 pounds to 1,700 pounds fully loaded.

The entire assembly rests on nine blocks placed in three rows of three at the front, back and middle of the tray’s base. HexaBlok components are made from Pactiv’s Hexacomb honeycomb structure which, in turn, is made from kraft paper (linerboard) and water-based adhesives. The paper is sliced into strips glued together to form a pattern of nested hexagonal cells similar in appearance to a bee’s honeycomb.

Its vertical cell orientation enables the honeycomb to handle heavy loads without a loss of strength. The water-based adhesives used to join components enable the structure to be recycled with other paper and paperboard products.

To produce the block components, Hexacomb honeycomb is wrapped around a core of the same material. This creates a structure that is performance-oriented, puncture resistant, costs less and is more durable than the expanded polystyrene, built-up corrugated and corrugated-wrapped alternatives, typically used for these applications.

These new block components deliver side-impact strength, similar to wood, to help defend shipments against rough handling by lift trucks. Also, the components are extremely light, which facilitates handling and contributes to lower shipping costs.

“The blocks also make material handling easier,” says Kelly. “The structure is less likely to be punctured by a lift truck and therefore makes it easier for the drivers to maneuver the pallet box.”

Distance Packaging is a division of F.X. Coughlin Co., focused on design and integration of highly customized supply chain packaging to customers with demanding and specific requirements in the automotive, retail, technology and transportation industries. Based in Taylor, Michigan, Distance Packaging provides automotive OEMs and suppliers with a competitive economic advantage and expertise in export packaging design. For more information about Distance Packaging, visit the company's Web site at www.distancepackaging.com.

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