One of the most common sustainability strategies is to eliminate shipping cases entirely. That means the palletizer has to handle primary packaging units instead of cases. This increases the end-of-line challenges many-fold.
By palletizing more primary packs instead of multiple packs inside a case, the rate of incoming product to the palletizer increases. So there is a trend toward a much higher unit-handling speed but, at the same time, the package is less stable and smaller.
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. 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.
Ironically, in some cases, the sustainable and economical benefits of slip sheets may be illusory. 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.
Even 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. 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.
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. 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. F&BP