Canadian Packaging

Many means to an end

While conventional automatic palletizers have been around sine the 1950s, their reign as the equipment of choice in end-of-line packaging applications may have seemed like it was coming to an end during the 1990s, when gantry and jointed arm robots started making significant inroads in palletizing—leading many in the industry to conclude that the days of conventional palletizers were well and truly numbered.


February 2, 2011
by Pat O'Connor, Intelligrated

While conventional automatic palletizers have been around sine the 1950s, their reign as the equipment of choice in end-of-line packaging applications may have seemed like it was coming to an end during the 1990s, when gantry and jointed arm robots  started making significant inroads in palletizing—leading many in the industry to conclude that the days of conventional palletizers were well and truly numbered.

But while there is no denying the robotic systems’ undoubted “wow factor” buzz and marketing cachet as new-generation “flexible automation” technologies for the high-throughput, high-SKUs (stock-keeping units) applications—as well as for handling irregular product shapes like pails or bags—there are still enough applications around where the “fixed automation” of conventional automatic palletizers makes more pragmatic sense.

Each technology has its own uses and advantages, with applications that favor the use of robotic palletizing typically including:

• Low-speed Multi-lines.
In order to handle more than one product at a time, a conventional palletizer needs to accumulate layers or loads of like product
on an upstream conveying system and then feed them into a palletizer that automatically changes the layering patterns, whereas
a palletizing robot can potentially simplify multi-line palletizing by eliminating the upstream conveyor system. By being able to build several loads inside the robot’s work envelope, the robots can allow the arm to work on all the loads at the same time, while storing the partial loads in cubic form at floor level. This is a very effective concept for lower-speed lines, generally when dealing with throughput speeds of 15 cases per minute, per line, or slower.

• Bag Palletizing.
Jointed-arm robots today dominate the bag palletizing business, incorporating clamshell tooling that allows the robot to pick the bag from a roller conveyor and place it on the load without disturbing the contents of the bag—resulting in a consistently straight and square load. Furthermore, the bag being dropped into place allows the robot to achieve higher rates than with case palletizing—frequently above 20 cycles per minute—with the robot’s inherent ability to work in confined spaces and dusty environments also making them an attractive equipment option in the bag palletizing business.

• Pail Palletizing.
Because most pails are constructed so that the bottom of the pail nests inside the lid of the pail below when stacked on a pallet, pail palletizing provides an ideal application for using robots, which can precisely and repeatedly place the pails so that each layer nests perfectly inside the previous layer.

• Display Loads.
Display loads frequently require fourway, labels-out orienting, multiple different sheets within a single load, special dunnage, etc., and while these requirements can also be addressed with a conventional palletizer, the cost of extra product handling may increase to the point where robotics can provide a more practical and cost-effective solution.

A Motoman palltetizing robot robot using powerful suction cups to build layers of boxed product onto a shipping pallet in a pre-selected pattern.

For their part, conventional palletizers still remain an effective option for following applications:

• High-speed Palletizing.
Conventional automatic palletizers are capable of achieving very high throughput speeds, which is why they continue to be routinely specified for high-speed manufacturing lines found in the food, beverage and many other consumer goods industries.
Surprisingly, they can also be more flexible than robots in regards to product packaging and stacking patterns, with some inline, continuous-motion palletizers capable of handling up to 200 cases and/or 20 layers per minute. Because robots are intermittent motion machines, it would take many of them working together to achieve these speeds, hence for high-speed manufacturing operations there is no better alternative to get the job done at required speeds.

• Reduced Product Packaging.
Essentially, robots pick and place the product, whereas conventional palletizers work by conveying the product into position.
Because they never have to pick up the product themselves, conventional palletizers are inherently more tolerant of packaging changes, with one such system capable of handling cases, trays, film bundles, poly-sacks, etc., with equal efficiency and reliability.

• Complex Pattern Forming.
Because conventional palletizers handle each case individually, any required pattern changes have a relatively small impact on the rate of throughput. In order to get reasonable throughput from a limited-cycle rate, robots are generally handling multiple cases at a time, so that if case sizes or stacking patterns change frequently, there will be a dramatic drop in the throughput rate.
For example, changing from a nine block, column-stacked pattern to a nine-block pinwheel pattern will frequently result in a 50-percent rate reduction on a robotic system.

• Conventional and Robotic Hybrids.
These palletizers combine articulated-arm robots with conventional palletizers—resulting in a effective solution that integrates the flexibility and repeatability of robotic arms with the speed and the reliability of the conventional palletizers.

The first common hybrid solution to combine conventional pattern forming with robotic layer deposit used the forming section of a conventional palletizer to form the layer, and a large robot to deposit the layer, turned out to offer few practical advantages, since the robot was too complex and slow a device compared to the conventional palletizer.

However, the concept of robotic pattern forming with conventional layer deposit really combines the best of both technologies for higher-rate applications, with robots being used to turn and position the cases precisely as required, while the conventional technology is used to square and deposit the layers of product.

Because the robot does not have to lift the product, it can operate at more than 40 cycles per minute on a wide range of package types, and because cases do not have to be positioned in fixed-lane locations, pattern flexibility is improved and new pattern creation is simplified. While the cost for this sort of a system is still higher than that of a conventional automatic palletizing system, the added expense can be justified in certain applications.

The Alvey 952 series palletizer from Intelligrated represents a new breed of hybrid palletizing systems combining the best attributes of conventional automatic palletizing technology with with the precisision and repeatability of robotics.

In summary then:
• Conventional palletizers will continue to provide a high-speed palletizing solution for many years to come. Robots cannot duplicate the continuous motion operation of high-speed palletizers or the flexibility of the palletizer when handling complex patterns and multiple package types, while the palletizers’ relatively low cost and flexibility will ensure their enduring popularity.

• While robots already dominate lowspeed, multi-line and bag palletizing applications, a growing number of new applications that will benefit from their robotic precision, combined with their “high-tech” image, will ensure the technology’s continued growth.

• Expect dramatic growth in the use of hybrid applications, where the robot functions as a component of a machine. There are already robots being used to manipulate cases inside the conventional palletizers, and as mass production continues to lower the cost of robotics, more and more applications—such as tier sheet inserting—are bound to be performed robotically sooner rather than later.

Pat O’Connor is the product manager for palletizing systems at Intelligrated, a leading manufacturer and integrator of automated end-of-line packaging and material handling systems headquartered in Cincinnati, Ohio.






Category Captains 2019
Machinery