Vacuum systems expert Simmatic was recently approached by mechanical handling company LAC Conveyors & Automation, to supply a convenient and cost-effective solution for a heavyweight lifting application. The challenging system was needed by a leading soft drinks manufacturer, which required a vacuum fixture that would reliably lift cardboard boxes containing foil pouches of drink syrup. As the boxes weighed up to 25 kg, and cardboard is a material that can vary greatly in porosity, this was never going to be a job for an off-the-shelf solution!
The purpose of the system is to transfer the boxes from the production line and stack them on a pallet, ready for dispatch. The design is based on a KUKA robot with a gripper at the end of its arm, gripper that was specifically designed by Ian Greenhalgh of Procanical. The Simmatic vacuum lifting system had to be an integral part of this gripper. A robot-based solution was chosen for this project because too little headroom and floor space was available to accommodate a conventional palletiser, and because the robot system offers outstanding flexibility in the eventuality that the size or format of the boxes change at some time in the future.
The Simmatic vacuum specialists faced two key challenges. The first was the weight of the boxes to be lifted – given the size of the vacuum fixture that could be accommodated, lifting 25 kg was no trivial task. The second challenge was that cardboard varies considerably in density and porosity so a large reserve of lifting capacity was needed to be designed into the vacuum fixture just in case a change was ever made to a more porous grade of cardboard for the boxes at some time in the future.
“While our experience means that we can readily design solutions even for challenging projects like this one, we always like to verify our designs by carrying out practical trials,” said Dale Simmonds, Managing Director of Simmatic. “So we requested sample boxes from the soft drink manufacturer and trialed our proposed head design at our in-house test facility. The trials, which were witnessed by LAC Conveyors & Automation, were entirely successfully. On the strength of this, we were given the go ahead to proceed with the manufacture of the vacuum fixture.”
The fixture uses a Magic Pump, with a capacity of 1340 litres per minute, in conjunction with four VB75 vacuum cups, each of which is nominally rated to lift 17 kg when operating at when operating at a vacuum of -60 kPa (-18 inHg). This components selection mean that the fixture has a large reserve of lifting power to guarantee good performance even if high porosity cardboard were to be used for the boxes. A digital vacuum switch to confirm that a good seal has been achieved with the box being lifted was also included.
Since the Magic Pump has eight vacuum ports, the cups could be connected directly to it, without the need for a separate manifold or pipework. This saved time, money and space, and maximised reliability by eliminating potential leakage points. A further benefit of the Magic Pump is that it has integral solenoid valves for suck and blow, so it was easy to make provision for the vacuum fixture to clean itself by blowing air through it between the lifting cycles.
The entire system weighed in at less than 900 g and proved easily small enough to be mounted directly onto the gripper. Creating the vacuum at the point of use means that the vacuum system is very responsive, so the pump only needs to run when the system is actually lifting a box. This is a sharp contrast with systems that use electrically-driven vacuum pumps, as these typically have to run continuously. Such an arrangement is far less energy efficient, and it also subjects the pump to greater wear-and-tear and increased maintenance requirements. In fact, the Magic Pump, which is powered by compressed air, has no moving parts at all, so it offers an exceptionally long maintenance-free operating life.
“We like working with the Simmatic team because they’re clearly experts in their field; they invariably develop practical, cost-effective solutions and they always stand behind their products,” enthused Steve Prior of LAC Conveyors & Automation. “We enjoy giving the team at Simmatic a challenge because they’ll always come back and demonstrate their proposed solutions using real product samples. This means that we can be sure of success before we even start working on a project – and guaranteed success is extremely valuable in a competitive business sector like ours!”
The palletiser system implemented by Simmatic and LAC Conveyors & Automation has been in use since September 2017, and the end user is extremely happy with its performance and reliability. Which just goes to show that the most innovative solutions really do come from creative and experienced engineers who like to think outside the box… especially if it’s a heavy box that requires Herculean strength to lift!