A producer of sweet teas and juices whose corrugated cases of product are palletized and stored in rooms where the temperature averages 35 deg F recently came to Motion Controls Robotics Inc. for help in replacing vacuum cups and pumps that weren’t performing adequately in such cold temperatures.
The problem is that the vacuum cups became rigid and the pumps wouldn’t provide enough vacuum to hold cases reliably. A better system had to be found to handle the cases, which can weigh as much as 42lbs (19kg). But due to the wash-down process, any kind of area gripper consisting of closed cell technical foam had to be excluded from consideration. Also out of the question were fork style or mechanical tools due to working-space limitations.
“With these two options eliminated, it was clear that the only possible solution would be cold-resistant silicone cups and high-quality, powerful vacuum pumps,” says Nathan Baker, Mechanical Engineer at MCRI. “So I immediately contacted Piab distributor Neff Distributor Group, who always provides me with multiple product suggestions as well as detailed engineering support. It was Neff’s suggestion, after further discussion with Piab on the most suitable pump, that we use the SX 12 ejector, a vacuum cartridge for Piab’s line of vacuum pumps and generators that generates the vacuum pressure.”
The SX 12, the ejector Piab uses in its flagship piCOMPACT®23 SMART pump for high-vacuum performance, is based on Piab’s COAX® vacuum generation technology. This ejector was particularly optimized for high reliability, flexibility, high vacuum flow, and fast cycle times, and it’s specifically recommended for palletizing solutions requiring large vacuum systems. That made it the right solution for the application that MCRI was working on.
Piab Application Engineer Oliver Lizotte elaborates further on why this particular ejector was such a good fit. “Thanks to its higher vacuum flow the SX12 ejector not only offers a stronger holding force but is also dust and debris tolerant—an important feature in packaging applications dealing with corrugated cases.”
The COAX® vacuum technology minimizes energy consumption and offers a safe and quick hold due to the high initial vacuum flow. COAX® ejectors are up to twice as fast as other ejectors and deliver three times more volume flow than conventional vacuum ejectors with identical air consumption. The ejectors can deliver high performance even when the supply pressure is low or fluctuating. This has been proven in independent comparative tests at the Fraunhofer Institute for Machine Tools and Forming Technology IWU in Dresden. These have shown that the Piab ejectors require significantly less compressed air than ejectors from other manufacturers to achieve the same performance. Since they have no moving parts, they are also practically maintenance-free and are resistant to most environmental conditions such as cold. Their use accordingly reduces the costs for the provision of compressed air as well as downtimes for maintenance intervals and thus the overall handling costs.
MCRI’s Baker adds this: “We conducted numerous in-house tests at MCRI to compare the SX12 holding force with that of the VGS™ 3010 generator using multiple different cups both in size and style. The result showed that the selection of the SX12 ejector is perfect. We also tested cups of various material for cold resistance by placing them for one week into a freezer, and then conducting different stress and compression tests on the cups thereafter. After that we knew that Piab’s silicone B75.20 cup was the right one for this application also because these cups are suitable for height differences and slightly uneven or curved surfaces particularly when several short bellows cups are combined in one lifting device. Piab’s policy of providing suction cups 30 days free of charge for testing allows us as system integrators to really test them in the application and be sure we’ve selected the best possible product in each case.”
The system starts with the Fanuc robot picking up a pallet and placing it onto a roller conveyor. To do so the end-of-arm-tool (EOAT) extends four mechanical clamps that grip underneath the pallet top. After the robot places the pallet on the roller conveyor the robot moves over to a plastic belt conveyor on which the cases filled with sweet tea or juice arrive to be palletized. Using the silicone B75.20 Piab cups, the robot’s EOAT grips a row of four boxes (nearly 170 lbs/77 kg) and places them on the pallet. After building two layers of product the robot grabs an intermediate tier sheet by extending four B50 multi-bellows silicone suction cups attached to VGS™3010 pumps placed at the outer corners of the EOAT. The cups perform a slight lifting movement to easily separate the thin tier sheets. For light weight tier sheet handling, the standard COAX® technology-based ejector performs reliably.
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Two of these palletizing cells are mirrored next to each other, both feeding a finished pallet stretch wrapper through a roll up safety door. The safety door prevents an operator from entering either palletizing cell.
Nathan baker of MCRI summarizes the improvements in the new palletizing cells, compared to the previous one. “With this case handling setup, we were able to gain an additional 10 lbs (4.5kg) of holding force per main cup. In fact, we went from a system dropping nearly every case to a solution that picks any case—even wet cases or cases with cut tape and glue where the flaps are loose. The EOAT with Piab’s B75.20 suction cups and SX12 ejectors still makes the pick!”