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HardPrecision – Precision hard milling

Automobile parts subject to high loads, such as drive shafts, gear wheels, and cardan joints, are formed using special tools. As well as having to meet increasingly demanding quality requirements, component manufacturers have to pay particular attention to the cost of the manufacturing process as a whole. Eleven partners working together in the EU project HardPrecision have developed an improved five-axis milling machine for high-precision hard machining. The results are being presented at EUROMOLD 2007 in Frankfurt.

“Automobile parts – for instance – and the cold-working tools used to shape them, are expected to last for increasingly longer. For this reason, they are made out of extremely hard, high-strength materials, but this also means that they are more difficult to machine. It’s a major challenge for the European tooling and moldmaking industry, because the parts have to be manufactured to a high standard of quality without driving up costs,” says Dipl.-Ing. Kristian Arntz of the Fraunhofer Institute for Production Technology IPT in Aachen. In current practice, the process chain in tooling and moldmaking involves milling, hardening, surface treatment by spark erosion, and often final finishing by hand. In the EU project HardPrecision, the Fraunhofer specialists teamed up with ten European partners to develop an improved machine for high-precision, five-axis hard milling. The industrial partners included component manufacturers such as Hemtech Machine Tools in the Netherlands, System 3R AB in Sweden and Walter Dittel GmbH in Germany, and also end users such as Hirschvogel Umformtechnik, Moldit SA in Portugal and Norma BV in the Netherlands. On the scientific side, the Fraunhofer researchers were supported by Research Center of Manufacturing Technology at the University of Prague. “One of the chief objectives was to reduce the process cycle for the tools,” Arntz explains. To do so, the researchers undertook a first-ever detailed study of the whole milling process – starting with CAM and NC technologies, and continuing with machine tools and tool coatings through to process monitoring. ”In HardPrecision, we took a broad view of the whole process chain. Our partners told us which materials they intended to work with in future. These mainly comprised conventional and powder-metallurgical cold-work and high-speed steels,” Arntz relates. To optimize the entire sequence of process steps, the scientists defined a number of separate work packages. This meant, for instance, having to reconfigure the process technology, given that one of the key questions addressed by the project was: What is the most cost-effective way of obtaining the necessary tool geometry? “The modern trend in manufacturing is to use a single forming process to produce increasingly complex shapes, for instance highly loaded steering system components. As a consequence, toolmakers are also having to deal with highly complex shapes. This in turn increases the complexity of the necessary machining tools and the design of the individual milling paths,” says Arntz, describing the problem. The solution found by the researchers was to adapt the machine to the new requirements by developing an optimized prototype with all-hydrostatic bearings. The improvements they implemented included the integration of lightweight structures and optimizing the coordination between the machine and the control system. Another work package involved programming suitable milling strategies to optimize path routing in the new manufacturing process. And lastly, the milling tools themselves and their coatings had to be improved, and solutions found for a multitude of minor process steps. ”At EUROMOLD, we will be using our machine to demonstrate real-life tool machining and the milling tools employed,” announces Arntz. Visitors can find out all they wish to know about the optimized five-axis high-precision hard milling machine in Hall 8, at Stand M122/L113.

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Austria, Belgium, Czechia, Germany, Denmark, Estonia, Greece, Spain, Finland, France, Hungary, Ireland, Italy, Lithuania, Luxembourg, Latvia, Malta, Netherlands, Poland, Portugal, Sweden, Slovenia, Slovakia, United Kingdom