Unitizing equipment stretches to meet demand
Unitizing equipment suppliers, including manufacturers of stretch wrappers, stretch hooding machines and strapping systems, have unveiled a variety of new features in their products to meet customer demand.
Users of end-of-line packaging machinery need units that can create high-quality, shipment-safe, secured loads of varying profiles at increased production speeds. They’re also paying particular attention to uptime, looking for equipment that requires minimal operator intervention to operate, reload and maintain.
In this article, Modern takes a look at some of the latest features in unitizing technology.
Stretch wrapper advancements improve load safety, quality
There’s been a big focus, directed particularly toward manufacturers of consumer goods, on improving the quality of stretch wrapped loads, says Jim Lancaster, CEO of Lantech. “Billions of dollars of product waste occurs annually because loads are damaged on the way from the manufacturer to the retailer,” he explains.
Stretch film tightly unitizes a load because it continuously attempts to contract back to its unstretched state. But, just because film is pre-stretched and applied to a load doesn’t mean the load won’t fail in shipment. Determining why loads fail, and how to stop them, is prompting shippers to develop and adhere to wrapping standards that minimize the risk of damage to product in transit, Lancaster says.
“Just by consistently doing three things—ensuring the load has the minimum amount of containment force, locking the load to the pallet, and tucking the beginning and ending tails into the stretch film—shippers can have a massive impact on damage reduction,” Lancaster adds.
“We encourage customers to look at their stretch wrapper not as the last machine at the end of the packaging line, but instead as the first and most critical machine at the beginning of their shipping and logistics process,” agrees Ric Lee, North American president of Aetna Group, manufacturer of the Robopac brand.
To help develop those wrap standards, suppliers of both automated and semi-automated stretch wrappers increasingly offer sophisticated test labs for load analysis. Lee’s company documents testing with high-speed photography showing how wrapped loads behave on shaker tables and acceleration/deceleration sleds, he says.
“This helps determine the correct way to wrap specific loads. Research has shown that to wrap loads correctly, to ensure that they arrive at their final destination free from damage, that you must control film placement, containment force and prestretch levels,” Lee says.
The latest machines are capable of delivering multi-level, variable containment force as they wrap the film in a spiral up and down a load. “Once the failure points in a load are identified, we can recommend the type of film that should be used and the amount of containment force required; the correct film placement and the optimal pre-stretch level for each load; as well as set up multiple wrapping menus so a single machine can wrap multiple types of loads,” Lee explains.
To determine the appropriate wrapping program for a given load, fully automated systems receive a signal from a palletizer, use a scanner to read load information with bar code, or are equipped with a sensor to detect load height or a scale to determine load weight. Alternately, semi-automated machines with human machine interfaces (HMIs) share graphical displays for easy wrap profile selection. Some even display the amount of containment force and prestretch applied to each layer of film.
In addition to accommodating multiple types of loads with multiple pre-programmed wrapping profiles, some of the latest stretch wrappers have multiple film carriages. A four-carriage machine, for example, can automatically switch between up to four different types of film, says Priscille Tremblay, Wulftec’s sales director.
“This feature allows one wrapper to service multiple production lines; alternately, it can be set up with four rolls of the same film for long, unattended production runs for labor and downtime savings,” Tremblay says. “Film can be reloaded from the back of the machine without stopping its operation, keeping the operator completely out of an unsafe area.”
That’s important for users who have recorded downtime as long as 5 minutes for film roll changeovers by experienced operators, Tremblay explains, “because of all the integrated safety devices they have to disable before entering the machine, and then reset after exiting.”
Other ease-of-use enhancements include the engineering of lower profile automated equipment with ramps that allow single, double or triple walkie pallet jacks to load the stretch wrapper with any style of pallet.
Stretch hooding as an alternative to stretch wrapping
Stretch hooding machines, which apply a cylinder of film over a load and seal it off at the top, offer a variety of benefits to users, explains Tim Bridge, application engineer at Beumer Corp.
“The film used in stretch hooding creates a one-piece, water-tight barrier that provides weather protection for loads stored outside or transported on flat-bed trucks,” Bridge says. “When combined with slip-sheets applied to pallets, full five-sided protection can be achieved.”
Further, the film itself can be branded with logos for displays, impregnated with ultraviolet (UV) light-blocking compounds, or made in dark colors that obscure the pallet load’s contents for security. On the flip side, the film can be completely clear to give handlers a view of the condition of the product inside, Bridge says.
For example, large appliances, such as refrigerators, used to be packed in big cardboard boxes with nearly $150 of protective packaging, he says. But manufacturers who have switched to clear stretch hoods have noted a significant reduction in packaging costs, as well as in damaged goods. “They attribute that savings to the handlers in their supply chain being able to see items and being more careful as a result,” he adds.
Stretch hoods can replace traditional secondary protective packaging because their application creates stability along two axes: The load is secured both vertically and horizontally with a single piece of material stretched over the entire pallet load.
That dual-axis containment force also uses less film when compared with stretch wrappers that wind loads only horizontally, and multiple times, to achieve the same stability, Bridge says. “If you compared two identical pallet loads—one packaged with stretch wrap film and one with stretch hood film—by weighing the film, stretch hooding uses significantly less film to achieve the same amount of containment,” he says.
Other recent stretch hood machine advancements include faster output speeds and reduced footprints, with the newest models using 30% less floor space than before. This is an advantage for companies that are decentralizing their operations into multiple facilities, says Bridge, because it frees up square footage for other production. Also, new, more-ergonomic designs enable floor-level access for maintenance and film changes, creating safer working conditions for operators.
Latest strapping systems boost uptime
Plastic and steel strapping unitizes loads, units and bundles of products, from construction materials like lumber and brick, to primary packaging containers, including beverage bottles and cans.
For safety reasons, many companies are moving away from steel strapping and hand application to plastic strapping applied by automated machinery, says Larry Ruud, process improvement manager at Signode. “Plastic strapping is less likely to cut skin, and it has better package tension qualities and better recovery characteristics than steel, keeping the bands tight should a load shrink,” he explains.
The latest strapping application systems feature smaller, easier-to-handle modular components that speed up changeovers. Some fully automated strappers can even refeed the strapping in the event of a misfeed without operator intervention.
“We’ve engineered smaller feeder and sealer modules that now weigh less than 50 pounds each, so operators no longer need forklifts or overhead cranes to do a changeover,” Ruud says. “The older systems combined feeding, take-up, sealing and cut-off into one strapping head that could weigh up to 300 pounds, and took over an hour to manipulate and change out. With these modular components, changeovers take less than a minute; they also make troubleshooting quicker and easier.”
Because of this, Signode’s service department has retrofitted many machines already in the field to these modular strapping heads.
Likewise, engineering advancements have boosted cycle speeds of special application machines to help keep up with increasing production line rates, dropping from 20 seconds to 10 to 15 seconds, says Ruud. “We’ve cut cycle speeds through programming changes, as well as built faster feed and take-up modules. Our bundlers can even put on 60 straps a minute to help keep up with fast-paced production.”
Companies mentioned in this article
Aetna Group: aetnagroupusa.com
Beumer Corp.: beumergroup.com
Orion Packaging: orionpackaging.com
Pallet Wrapz, palletwrapz.com