Precise control of air pressure and innovative dunnage air bag design better stabilize truck freight
North American supply chains for manufactured goods depend heavily on trucking. In fact, 72% of all shipments in the United States travel on truck trailers. And according to statistics from the U.S. Bureau of Transportation, trucking was the #1 mode of transport for shipments of freight between the U.S. and Canada and Mexico in 2017 valued at over $721 billion.
The cause is often the “start and stop”, bouncing and turning of trucks during transit. When double-stacked in truck trailers, palletized goods can have a relatively high center of gravity. In most cases, the pallets do not fit snugly together, leaving plenty of space for the pallets to shift in transit. Even low-density products, like empty aluminum cans, can be affected by vertical movement that can create enough energy to damage the product if not stabilized.
When this occurs, both the product or the packaging can become damaged. Damaged freight impacts all layers of the supply chain. The costs of damaged product or packaging impacts the manufacture, the distributor and ultimately the end consumer.
Even when product or packaging is not damaged after it tips over, warehouse employees or customers must spend time re-stacking them in order to unload. That work is not only inconvenient, but time consuming. It can take up to an hour to re-stack one pallet. To re-stack a complete load could take as much as an entire day – a very significant expense. Safety risk is also a concern when re-stacking, both for employers and the Department of Transportation.
To address these concerns, the industry has typically turned to a variety of dunnage materials and methods including plywood, matting, strapping and load bars to stabilize and secure truck loads during transportation. However, some of these options can be problematic for shippers, and billions of dollars are still lost annually due to products damaged as a result of inadequate dunnage.
This is causing the industry to consider ‘out-of-the-box’ dunnage solutions to fill the empty spaces. At the top of this list are more advanced inflatable truck dunnage bags that can be inflated to precise pressure levels during the loading process. These solutions provide a host of benefits and are fully recyclable, making them one of the lowest cost dunnage solutions on the market.
Inflatable dunnage air bags
Estimated at a $420 million market in 2017 and projected to reach $740 million by 2026, dunnage air bags are one of the most popular solutions today for freight stabilization and protection.
Historically inflatable air bags have either used woven polypropylene, Kraft paper, vinyl or other combinations of materials to cover an air bladder. With the exception of Kraft paper, most are manufactured overseas. Designed for single trip use, air bags offer the advantage of being configurable and effective freight stabilizers for voids of up to 24 inches between pallets.
However, air bag design has continued to advance with improvements that lowers overall costs and improves performance for freight loaders and haulers.
“The material used to make the bag, the valve, inflation gun and other subtle – yet important - design features can add considerable value to this type of dunnage,” says Mitch Tschantz, owner of Inflatable Packaging Incorporated (IPI), a Connecticut-based inflatable packaging and dunnage solutions provider founded in 1993.
Inflatable Packaging, for example, has developed a transparent air bag solution for their Air-Lock™ truck dunnage bags that is made of a fully recyclable polyethylene material. Unlike woven, paper or vinyl materials, the dunnage bags are made of a transparent film, which gives the bags lower weight and handling advantages. Because the film is extensible, which means it can stretch and expand (unlike inflatable air bladders with covers), which is a valuable feature at varying altitudes.
Because the material is clear and not opaque like other dunnage solutions, inspections are expedited. This is ideal for international shipments from OEMs with manufacturing centers in Mexico or suppliers from Canada. “With a bright light, inspectors can see through the material all the way to the bulkhead of the trailer to ensure there is no smuggled contraband or illegal border crossers,” explains Tschantz.
The polyethylene bags can be pre-positioned in the warehouse prior to loading, or in the trailer, using double-sided adhesive labels. The inflation valve can be either at pallet top or bottom for easiest inflation process. For forklift operators, pre-attaching bags to pallets in the warehouse can expedite the loading process by 25-30%.
The surface of the polymer bags is also treated with a charge of electricity so it clings to the stretch-film used to stabilize goods on pallets. Other types of bags, including those with paper covers, are known to migrate out of position as a result of bouncing and shifting during transit.
The valves used to inflate the bag are also a critical part of the overall design.
“The valve design affects the speed of inflation and allows for pressure adjustments as needed. In addition, our valve is manufactured with the same material as the bag so it can also be recycled without any required separation,” says Tschantz.
For this, Inflatable Packaging developed and patented a self-sealing “flat” valve system that allows for inflation and deflation. The company’s Venturi-Action Inflator gun can fill most truck dunnage bags in less than 30 seconds to the pressure that matches the load density required for stable product shipment.
According to Tschantz, the ability to precisely control air pressure in the bags was a benefit to an OEM based in Mexico that was shipping flat-panel televisions throughout North America. The company had a high damage rate due to bag expansion at high elevations.
“The manufacturer was incurring a damage rate as high as 14% when they would ship product from their sea level facility to Mexico City at an elevation of over 7,000 feet or through the Eisenhower Tunnel in Colorado where the elevation rises to more than 11,000 feet,” says Tschantz. “The expansion of the bags was crushing some of the boxes.”
Inflatable Packaging recommended using their patented inflation gun to adjust the pressure to precise settings to accommodate the expected elevation changes on the route.
“The damage rates for the OEM dropped from 14% to less than 1%, which dramatically reduced the amount of goods that had to be marked down at retail,” explains Tschantz. “Those markdowns were often up to 40% off of the original price when the boxes were damaged, even if the television inside was completely fine.”
Addressing diverse freight needs
Freight comes in all shapes and sizes each with its own unique stabilization requirements. Sometimes it is not only about the bag you select but how you deploy it.
Take shipments of empty aluminum cans, also known as “shiners.” When shipped to beverage processors, vertical movement within a trailer can cause an up-and-down motion that generates enough energy to crush cans. By positioning inflatable bags on top of the load, the vertical movement is controlled.
Refrigerated freight is another key market for truck dunnage bags as shippers have the additional concern of maintaining perishable goods such as fruits, vegetables and meats in optimal condition during transit. With traditional dunnage, refrigerated air fills the entire trailer but is not directed optimally.
Instead, dunnage bumpers can be used. Bumpers are similar to dunnage bags, but are long and skinny – up to 25’ in length. The bumpers help control truck airflow so the cold air blows up through the inside of pallets instead of randomly filling the entire area. This refrigerated air flow can include special gases used to enhance preservation of fruits and prevent early ripening.
“By controlling the refrigerated air flow, less money is required on fuel and less refrigerated air is required for temperature control. It also works for gases used to extend the time it takes for fruit to ripen,” says Tschantz.
Source reduction and recycling
In addition to the advantages for shipping, inflatable air bags provide significant source reduction and recycling opportunities.
Transportation costs, for example, can be reduced since a single pallet of Air-Lock air bags can replace 2-3 pallets of other dunnage options. When compared to other air bags, those with low profile flat valves only a few mils thick can be stacked 1200 per pallet, as opposed to 300-400 if traditional 1 ½” height valves are used. These same features also impact storage and handling.
Inflatable dunnage bags are also recyclable after use, particularly those made with a flat valve design constructed of the same polyethylene material. When this not the case, the non-recyclable components must first be separated, including any metal spring valves or external covers. Given the amount of work it requires, however, most bags that are not 100% recyclable instead end up in landfill.
“Truck dunnage has advanced well beyond simply filling voids inside boxes and between pallets,” said Tschantz. “It now is about solving unique challenges that come with the size, shape and temperature requirements of their goods - even the shipping routes that they take. Smart design and customized solutions are improving efficiencies, better protecting goods, and reducing costs in supply chains.”
