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Resource-saving production of high-performance components
The so-called online prepreg facility, which was financed by the DFG, the state of Lower Saxony and Clausthal University of Technology with a total of around 1.2 million euros, has started operations.
Fiber composites are used in high-performance components for the aerospace industry, mechanical engineering, the automotive industry and the sports sector. They impress with their excellent mechanical and physical properties. In the field of these materials, prepregs are particularly popular due to their simple and good processing options. A prepreg - the term comes from the English word pre-impregnated- is a fiber fabric impregnated with resin, which exhibits high reproducible properties in the semi-finished product and transfers this property profile to the components made from it. However, there are also some material-related disadvantages. Researchers at the Clausthal Center for Materials Technology (CZM) want to eliminate these problems in the future through extensive research work on a new large-scale device.
The system was developed at Clausthal University of Technology and funded to the tune of around 1.2 million euros by the German Research Foundation (DFG), the Lower Saxony Ministry of Science and the university. The machine sets a new, innovative and future-oriented standard in prepreg technology. "Improving the utilization of raw materials, avoiding contaminated waste and reducing energy consumption are just as much in focus as the development of highly complex components, shortening process times and improving the mechanical properties of the end products," explains Professor Gerhard Ziegmann from the Institute of Polymer Materials and Plastics Technology.
The previous problem with prepregs: for complex geometries, component sections have to be separated from a continuously produced semi-finished product, which is associated with large amounts of waste of up to 40 percent. This waste cannot be recycled or can only be recycled at extremely high cost. This drastically reduces thecarbon footprint of fiber composite applications. Furthermore, the semi-finished products have to be stored at a temperature of minus 18°C, which has an additional negative impact on the energy balance.
The Clausthal system now reverses the principle of prepreg production - first cutting, then impregnation and curing - and thus solves the problems described. The operation of the online system can be divided into several stations: First, the stored, dry semi-finished product is cut to the desired component shape fully automatically. The residual material can be reused or recycled without any problems as it does not come into contact with the reactive resin. If required, for example in the case of natural or aramid fibers, the textile structure can be dried in the next step directly before impregnation in order to exclude the effects of moisture. The textile or subsequent component is then precisely impregnated with a freshly mixed resin-hardener mixture. This innovative application method largely avoids resin waste and prevents contamination of the residual material. In the last station, the controlled start of the chemical curing reaction (B-staging) takes place in order to shorten downstream production steps, such as the final shaping and final chemical reaction in a heated pressing station.
"The process realized with the online prepreg system represents a milestone for the resource-saving production of high-performance components in a wide range of applications," say Professor Ziegmann and doctoral student Grigori Oehl. Future collaborations with partners from industry and research will ensure optimization and prompt transfer for large-scale applications.
Video server: Innovative fiber composite process for lightweight construction concepts
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TU Clausthal
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Christian Ernst
Phone: +49 5323 72-3904
Email: christian.ernst@tu-clausthal.de
