Kuka Oversized plastic pipes milled to perfection
KUKA supplies technology package to Asset International in Wales for milling Weholite pipes measuring up to 3.5 meters in diameter.
Plastic components, for example for underground pipelines, are a specialty of the Finnish company Uponor Infra. With its product Weholite, the company has developed a patented solution for manufacturing plastic pipes several meters in length and up to 3.5 meters in diameter. These oversized pipes are used for such applications as gravity-based drainage systems, dewatering, subterranean canals, retaining basin systems and low-pressure applications. Weholite pipes boast all of the technical advantages of full-wall PE pipes, but are lighter, react flexibly to earth movements, and can be more quickly and easily installed thanks to the high degree of prefabrication. Eugen Riexinger GmbH & Co. KG in Bad Liebenzell has developed a fully integrated, automated solution for the milling of the huge pipes at the factory of Weholite licensee Asset International Ltd. in Newport, South Wales. For this purpose, KUKA supplied not only the KUKA 120 R2700 extra HA robot, but also the KL 1500-3 T linear unit, two MG 360 KUKA servomotors for the external rotational axis and the KUKA CNC controller. “This is our pilot project for robot-based automation,” explains Graham Bennett, Operation Manager at Asset International.
The goal: to increase flexibility, improve precision and reproducibility
“The biggest challenge of the automation project was the reliable and flexible machining of the unusually large components with different contours and shapes,” explains Markus Theobald, Managing Director of Eugen Riexinger GmbH & Co. KG, which developed the solution for Asset International. The company from Bad Liebenzell ranks among the world’s leading providers of customized plastics welding equipment, welding machines and pipe saws for the processing of pipes, moldings, fittings and profiles made of plastic. In order to increase flexibility and work safety at Asset International, not to mention improve the precision and reproducibility of the milling tasks – which until now were carried out exclusively by hand – Riexinger needed a modular, integrated and easy-to-operate solution comprising a robot and milling spindle. One of the Riexinger’s main goals is the development of modular systems. “These enable our customers to successively expand or adapt their systems to new requirements,” says Theobald. With the combination of a six-axis robot with greater stiffness for the machining process and the corresponding KUKA CNC Milling package, Theobald asserts that KUKA offers the best – as well as the only – fully integrated solution on the market by far. The first application for smaller components was successfully installed at the customer’s site at the end of 2013. “We have gradually developed the system in collaboration with KUKA and adapted it to the customer’s requirements.” An additional focus here was on clamping the oversized components as simply and flexibly as possible.
Flexible clamping and machining
The KUKA 120 R2700 extra HA robot from the KUKA KR QUANTEC series for payloads of up to 120 kilograms is designed for high-precision requirements such as milling and laser applications. At the Asset International plant in Newport, it machines the large plastic pipe components with a specially designed high-speed milling spindle. Prior to machining, workers clamp the components to a multi-functional clamping table or a large, self-centering table controlled by the rotational axis. As a result of the barrier-free system, the robot, mounted on the linear unit, can move directly to the plastic pipe to be machined and then flexibly carry out the job on the component as required. “In this way, our employees are relieved of what was until now very strenuous manual work involving high levels of vibration,” says Bennett. Furthermore, the employees no longer have to climb on ladders and platforms in order to perform manual preparatory work such as measurements with compasses, tapes and gauges, cutting with a saber saw or chainsaw and surface finishing with a grinder or electric hand plane. According to Bennett, this plays a significant role in the employees not regarding the robot as a threat to their jobs but rather as a helpful assistant for difficult tasks and a member of the team.
50 percent increase in productivity and more
“The solution has enabled us to significantly increase productivity,” says Bennett happily. “Shorter production times have allowed us to boost capacity by more than 50 percent. At the same time, he emphasizes that there has been a marked improvement in quality and precision.” Asset was able to achieve improvements in quality, in particular thanks to the high level of reproducibility. This optimizes the subsequent production step of welding over the long term. Here, not only the weld times but also the consumption of welding material can be reduced thanks to the consistent preparation of the joining gap and weld seam. In addition, health problems ensuing from manual labor involving heavy vibrations have been eliminated, and safety has been increased. Thanks to its modular design tailored to the customer’s requirements, the system can be adapted to the needs of Asset International at any time. Riexinger is also very pleased with the result. “We are very proud to have designed the first system worldwide that can process such large plastic parts with this precision and speed – all the while increasing occupational safety,” emphasizes Manuel Kratz, head of the project at Riexinger. For this reason, the Bad Liebenzell-based company is sure that robot-based automation in the plastics processing sector will be seeing further growth. “There is a great deal of potential, in particular with regard to Industrie 4.0. What is more, the demand is already coming from our customers,” says Theobald optimistically.