As part of the research project "Hybrid Pultrusion", the Fraunhofer Institute for Machine Tools and Forming Technology (IWU) in cooperation with the Leibniz Institute of Polymer Research Dresden (IPF) is working on the production of multi-material profiles in a modified pultrusion process.
In the conventional pultrusion process, continuous fibers or textile semi-finished products are impregnated with resin and pulled through a heated die. The curing of the resin produces a continuous profile with a constant cross-section equal to the die cavity. The pultrusion process is characterized by high efficiency due to excellent material utilization and high production speeds. Against this background, pultrusion profiles have already established themselves in the construction industry or wind power industry.
In order to open up new areas of application, profiles are hybridized in this project by integrating other materials such as metals. For example, the performance of a fiber composite structural component can be specifically influenced by embedding a further component. In addition to adapting the mechanical properties, further modifications such as thermal and electrical conductivity or energy absorption capacity can be achieved through metal hybridization of the pultrusion profiles. The bonding between metal and impregnated fiber materials takes place during resin curing in the pultrusion die. A special powder coating is applied, which realizes a covalent matrix-metal bond and thus exhibits very high bond strengths. In addition to technical process challenges such as targeted material feed and temperature control, a parallel simulation adjustment was also carried out in the project. A complex project demonstrator based on possible applications in transportation was realized through extensive preliminary investigations of simple plate and strip geometries.
Overall, the project was able to extend the economic efficiency of the established pultrusion process to hybrid materials and at the same time demonstrate a shortening of the process chain compared to the conventional bonding process. With the new developments, hybrid structural components can be produced very economically from pultruded profiles in the future in order to be used in other industries.