Getting the most from your stretch wrap
February 03, 2011 - MMH Editorial
As shippers focus on taking costs out of their supply chains and reducing the amount of material that goes to the landfill, they are also taking packaging material out of their loads. “The corrugated is thinner, we’re taking product out of cases and putting it in trays, or in some cases, the primary package is now supporting the load,” says Jim Lancaster, president and CEO of Lantech, the maker of stretch wrap systems. “At the same time, they’re not thinking about the secondary package, such as the stretch wrap. That’s when they end up with damage.”
Echoing Mark White’s theme about unit load design, Lancaster says shippers can no longer look at just their pallet – or the stretch wrap going on their load – in isolation. They have to understand the eco-system in which the unit load will operate, and the biggest impact on that today is sustainability.
Examples: Paper towels and bottled water both used to be shipped in cartons. Now, they’re both just stretch-wrapped to a pallet. And, in the case of water, the bottles themselves are manufactured from a thinner gauge plastic. “It’s like you’re shipping one big water balloon,” says Lancaster.
How then do you wrap a load so that it arrives at its destination in the same way it left the factory? Lancaster has several tips Lantech defines as lean wrap.
Focus on containment force, not the gauge of the film: “Containment force is the most important thing that determines the way a load arrives at its destination, not just the thickness of the film,” says Lancaster. Containment force is a function of the amount of force applied as the load is rotated and the number of layers of film. Put another way, ten wraps of a thick film provides the same containment force as 20 wraps of a proportionately thinner film if they’re applied with the same force.
Create a uniform wrap: Some customers mistakenly believe that putting more film at the top and bottom of the loads, then skimping in the middle will hold an unstable or top heavy load in place. Lancaster says that’s a misnomer. “As a truck travels down the road, layers on the load shift from vibration – we call it a harmonic,” he says. “Our experience tells us that the weakest point on the load is where it will fail.” For that reason, Lancaster suggests that shippers uniformly distribute the film around the load.
Tuck in your tails: Have you ever tripped over your own untied shoelaces? There’s a corollary when it comes to stretch wrap, which is the tail of film that’s left after wrapping a load. “Those tails look terrible,” says Lancaster. “More importantly, they can get under the tire of a forklift or stuck in a conveyor roller. Then, it’s a bit like stepping on a shoe lace and can cause a load to shift.” Make sure then that you tuck in your tail.
Attach the unit load to the pallet: In addition, to tucking in the tail, be sure that the film locks the load to the pallet. “Otherwise, it’ll vibrate off the edge of the pallet. Then the stacking strength is compromised and it’s susceptible to damage,” Lancaster says. Lantech has performed incline tests that simulate a pallet going into a rail car or a truck and found that when the bottom 20% to 30% of the web of film is rolled into a cable just above the fork opening, there is a dramatic improvement in load performance, a feature that Lantech has built into its next generation of wrappers.
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