Cartoning made simple

Carton sizing

One discovery regarding the cartons had to do with dimensions, which had to be expanded slightly. “A human can squeeze primary packages into a carton in a way that a robotic end effector can’t,” says Rettig. “The robot needed a little more clearance, especially at these speeds.”

Cartons are conveyed around a 90-degree curve single file and enter a Delkor Robotic Loader anchored by a Fanuc M-3 robot arm. Also being conveyed into this machine are the protein bars themselves. These are wrapped in a two-layer extrusion lamination of 80-ga Oriented Polypropylene and 60-ga metallized PET. The OPP is reverse printed in five colors on a gravure press. A pattern cold seal provides the means by which the flexible film is formed and sealed around each bar, and the date code is printed on the inside of each fin seal.

While the Formost Fuji flow wrapper has been around for some time, a checkweigher from Mettler-Toledo Hi-Speed is a new addition. Any bar whose weight is outside of preset parameters is automatically rejected.

The protein bars move into the robotic load cell at an impressive rate of 400/min when the 35-g bar is in production. They enter a servo-driven carrier that takes them at a right angle in groups of 12 and positions them where the robotic end effector can pick them. With each cycle, vacuum pickup cups on the end effector of the robot arm pick 12 bars and place them in two waiting cartons. For the larger 55-g bar, the format is two layers of six for a total of 12 protein bars per carton. For the smaller size the format is four layers of six for a total of 24 protein bars per carton.

Two servo-driven carriers

The only way to keep up with the 400 bars/min speed is to use two servo-driven carriers. So the two are mounted on a sort of an oval-shaped race track device. While the vacuum cups are picking bars from one carrier, the other one is being filled. When one is emptied of its bars, it quickly follows the oval-shaped track back to the station where incoming bars can fill it, and the freshly filled carrier moves in to have its bars picked.

A photoeye from Sick detects the spacing of the bars as they shoot into the robotic cell. If any bar is crowded so tightly against another that it might cause a jam when it reaches the servo-driven carrier, a burst of air kicks that bar off the line. A second Sick photo cell ensures that 12 bars are in the servo-driven carrier, and if any are missing, that carton is later rejected.

Filled with their full complement of protein bars, the cartons are discharged from the robotic cell and make a right angle turn into the Delkor Capstone M Closer. First a stationary overhead bar pushes the top flap down as the carton is pushed beneath it. Once in a fixed position, adhesive is applied to the three sides of the carton by a Nordson device. Then pneumatic arms close on the three sides and hold the flaps briefly until the adhesive has set. Finished cartons then pass through a laser coder from Markem-Imaje before being discharged from the carton closer.

“Durability and ease of use were our requirements,” says Rettig. “I also wanted to be sure there would be no drop-off in speed. Delkor responded with a servo-driven, all-stainless steel solution. And by giving them turnkey responsibility, we eliminated some of the complexity that can creep in when you are dealing with multiple machinery vendors. For example, even before the Factory Acceptance Test at our own plant, we were able to conduct a pre-FAT at Delkor’s plant. We wanted to watch it running at 400 bars per minute before even taking it to our facility. That would have been difficult to arrange if more than one machine builder was involved.”