Technology | automation
equipment to end up in China via a customer in Europe or the US. A cell Hekuma recently supplied to German customer Söhner for automotive component production in China is typical. It was the fourth such cell supplied to the company, which already has three systems running in Germany. This fourth system was delivered to and run-in in Germany before being shipped to Söhner’s China operation. The automation cell is designed to produce gear
covers for front windshield wiper systems. The covers consist of three components in 30% glass fibre reinforced PBT, as well as a TPE seal. The manufactur- ing process involves inserting six metal contacts into each of the four cavities in the mould. Then, in a subsequent process, an additional contact is bonded into position with hot-melt adhesive. Contact insertion, assembly and inspection are
broken down into eight, fully automatic processing steps. “This specification can only be achieved if each processing step is synced exactly to the others,” says Ralf Kümmerle, project manager at Söhner. The take-out and insertion process is completed
over four cycles. After the contacts are punched, bent and separated, they are inserted into the tool and then overmoulded with PBT. The components are then conveyed to a transfer station, rotated through 180˚, and picked up again by the gripper. In the next step, the components are put into a new cavity and the TPE seals are injected. The final part is then extracted and passed on to downstream operations where a series of performance checks are completed. The individual insertion and take-out steps per-
formed by the independently-moving gripper elements run parallel to one another. Four parts are produced every thirty seconds. Each cell makes two million gear covers per year, giving Söhner a total output of eight million across the group. Wanner says the robots at the heart of its automation
systems are virtually always side-entry linear types, which it builds itself. “We have systems that are installing as many as 120 contacts into a mould, sometimes even more,” he says. “This requires a lot of mechanics in the gripper, so you end up with a gripper system weighing as much as 200kg, and you cannot handle that with a six-axis robot. We also prefer linear robots for speed and precision, and ease of handling. We may use six-axis types for upstream and downstream operations, though. Sometimes we also use six-axis robots for simpler insert moulding applications, some customers prefer them
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because they are more flexible and easier to re-purpose. But in the end it’s just a robot, it’s not such a big amount of money.” Ultimately, in the world of
automation, it is a question of using technology that is fit for the purpose. Today, processors are almost spoilt for choice, and
systems of all types are becoming increasingly cost-competitive. “We’ve
observed two recent trends,” says Oliver Giesen, Manager of Arburg’s Project Depart-
ment. “On the one hand, the complexity of the turnkey systems is increasing. On the other hand, customers are seeking very flexible automation solutions owing to ever smaller batch volumes and faster product changes.” If the customer requires a high degree of flexibility
for insertion tasks, interactive operation with human/ robot cooperation can be a good solution. “Because the operator places the inserts manually in the gripper, expensive provision and feed devices for the inserts can be dispensed with and the system can easily be used for other products. Where both high flexibility and high complexity are required, a mobile robotic cell…is an ideal solution,” Giesen says.
Click on the links for more information: ❙
www.engelglobal.com ❙
www.kraussmaffei.com ❙
www.arburg.com ❙
www.kuka-robotics.com ❙
www.staubli.com ❙
www.fanuc.com ❙
www.sepro-group.com ❙
www.rangerautomation.com ❙
www.yushin.com ❙
www.wittmann-group.com ❙
www.cbwautomation.com ❙
www.star-europe.com ❙
www.hekuma.com
Left: This gripper system forms part of an automotive gear cover production system developed by Hekuma for Söhner
Left: Söhner of Germany is using four Hekuma automation systems to produce this multi-compo- nent gear cover
July/August 2015 | INJECTION WORLD 37
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