Palletizing and other unitizing operations can accommodate the sustainability drive with the right adjustments.
The drive for sustainability is affecting all parts of the packaging line. Including the end.
As food and beverage packagers strive to take as much material as possible out of their packaging, both primary and secondary, end-of-the-line equipment and materials have to be adjusted. Palletizing and stretch wrapping equipment have to handle lighter, weaker, less stable packages. In addition, sustainability considerations come into play in terms of loading pallets for maximum transportation and storage efficiency.
“The thing that is driving us crazy at the moment is the push to sustainability,” says Martin Clark, director of marketing and business development at FKI Logistex North America.
No caseOne of the most common sustainability strategies is to eliminate shipping cases entirely, Clark says. That means the palletizer has to handle primary packaging units, like beverage six- or 12-packs, instead of cases. This increases the end-of-line challenges many-fold.
“By eliminating the box, you have basically taken what we’ve been obliged to palletize and divided its size by three,” Clark says. “But if it’s a typical manufacturing environment, you’re going to run the filler or whatever’s upstream at the same speed, so you’ve basically not only reduced the size of the package by a third, you’ve increased the rate at which we receive them threefold. So what we’re seeing is a trend toward much higher unit-handling speed, but at the same time, a reduction in the stability of the load that is being handled.”
Not only is the load going into the palletizer less stable; so is the load on the pallet. Standard cases can quite easily be built into interlocking loads, where the gaps between cases alternate. But as the units on the pallet become smaller, column stacking, which is inherently less stable, becomes the only alternative.
Slip sheets often are a solution to the elimination of cases, Clark says. A customer who wants to maintain line speed while eliminating cases will often have to buy a faster palletizer to compensate for the additional time it takes to insert the slip sheets. Slip sheet insertion also can be retrofitted into existing FKI Logistex palletizers, although obviously in those cases the extra time can’t be compensated for.
Ironically, in some cases, the benefits of slip sheets may be illusory, Clark says: “If you’re reducing the amount of secondary packaging, you may be adding just as much into the pallet load [with slipsheets] to allow you to still handle it. So the net benefit may not even exist.” But a packager under a mandate from Wal-Mart or another trade customer to reduce packaging may still find it necessary to make the tradeoff.
Ends and meansEven when cases remain, they may be altered for the sake of sustainability. For robotic palletizers, the most common end-effector-the equipment at the end of the robot arm that actually contacts the case-is the suction cup. That works fine if the case has a solid, sealed top, and the weight of the product can be supported by the case alone.
But if a case is trimmed of material-using, for instance, two top flaps instead of four, or using flaps that leave a gap when closed-there won’t be a solid enough surface for the suction cup to get a grip. Clamps are an alternative, if they don’t crush the less robust case; if that’s a liability, forks that close underneath the case might be the best bet.
The sustainability drive has led to reduction in primary as well as secondary packaging. End-of-line equipment has to take that factor into account, often through gentler handling.
The need for gentle handling is especially prominent in beverage applications, because many glass bottles have been lightweighted, says Kevin Kozuszek, marketing manager for Kuka Robotics. One possibility to insure gentle handling for relatively high-speed lines is a combination of robotic and conventional, or ram-style, palletizing. The robot orients individual cases into rows before the palletizer pushes them onto the pallet. This allows the palletizers to work faster while reducing impact on the cases.
“What we’re seeing a lot of end users and even some manufacturers saying is, if we could get a robot up there to orientate and place the layers by coming down on top of the case, rotating it and moving it and placing it, that’s going to reduce the actual physical pressures that’s hitting the cases,” Kozuszek says.
Bump and runEven simple changes to infeed material handling can decrease the stress on cases and their products. Some FKI Logistex conventional palletizers use “bump turners” to rotate some cases 90 degrees on their way to the palletizers. If cases need gentler handling, FKI can install (or retrofit) a bump turner backed by an air cylinder, to lessen the impact on the case.
Another way material-handling systems can maintain or increase palletizing speeds while minimizing impact is by forming rows or layers of cases before they’re picked up by a palletizing robot, says John French, director of sales and marketing for BluePrint Automation. Assuming that the line is relatively dedicated (meaning the case sizes rarely change), the cases get shuttled into line so that several of them can be picked up at a time and swung onto the pallet.
“Prearranging an entire layer, instead of having the robot build that one case at a time, helps quite a bit,” French says. Usually, the extra payload isn’t a problem for the robot, he says, pointing out that many robots used in packaging got their start in the automotive industry, where average loads are far higher.
“Sustainability has meant that there’re more things we typically need to take into consideration when doing a successful palletizing project,” French says. “In the past it was always just: ‘Calculate how fast do you need to go. Do you have enough speed in your palletizer?’”
It's a stretchSustainability concerns also come into play with the next step after palletizing: stretch wrapping.
There’s a paradox at play with sustainability and stretch wrapping, says William Caudill, marketing manger for innovation at Lantech. As cases get lighter, they get easier to crush, meaning that the film can’t be drawn as tightly around the load. But wrapping the film with less force means using more of it, creating a new waste issue.
Lantech has addressed that problem with the RS 6000 stretch wrapper, which made its debut at last year’s Pack Expo. Instead of feeding film as a response to tugging by the revolving arm, the RS 6000 pays out film at a predetermined rate, using just enough for the job.
That payout rate has to be customized for each kind of load, Caudill says: “There’s no magic chart out there that you look at and say, ‘If I’m shipping boxes that weigh this much, here’s how tightly I should wrap it.’” This is why mixed pallet loads, very much in demand by some trade customers, can be such a challenge: “If they have mixed loads, they’ll try to find a happy medium-one setting that will work for every one. Which, again, leads to some loads getting a lot more film than they need.”
The RS 6000 is currently recommended for dedicated palletizing operations that don’t change often, although Lantech does have a model under development that will be able to store multiple preprogrammed wrapping profiles.
Cube efficiencyPallet-related sustainability concerns go beyond the four walls of the packager’s factory. Transport costs are a major component of a product’s “carbon footprint”-and are recognized as such by the Wal-Mart Sustainability Scorecard. That’s why building a pallet to best advantage is a vital concern in sustainability, says Brad Leonard, vice president of business development for Cape Systems, which markets pallet-pattern software.
“I think the industry is going to quickly find out that the cost savings that also give them the best scorecard numbers are probably going to be after the package is built and put on the pallet,” Leonard says. “I think the cost of the package is going to actually fall second to the cost of moving the package around.”
Using truck and warehouse space as efficiently as possible means taking that space into account when pallets are being built. For instance, Leonard says, instead of building every pallet 48 inches high, it might optimize cube use in a warehouse to build some at 43 and some at 52.
Leonard says that driving costs out of primary and secondary packaging may be reaching a point of diminishing returns. Concentrating on the palletization cube may yield more rewards.
“It might be that we spend even more money on the packaging materials, because that gives us more opportunities somewhere else,” he says. “A thinner, different kind of material that gets you more on a pallet may cost you a few pennies more than corrugated, but that whole effect then snowballs through the supply chain.”
For more informationThe following companies contributed to the development of this article:
FKI Logistex North America