Paintable CFRP componentsThe surface RTM process developed by KraussMaffei and its partners enables cost-effective mass production of paintable fiber-reinforced visible components for automotive construction. Paintable components are created by flow-coating the component surface produced by surface resin transfer molding with a polyurethane layer directly in the cavity, without the need for any additional intermediate steps. Costs can be reduced by as much as 60% per component, as there is no need for expensive post-mold finishing, which often needs to be carried out manually. The polyurethane for both the supporting part and its surface is poured in when the mold is slightly open (compression RTM). This produces only a very low flow resistance, which allows injection of the polyurethane system with comparatively high pour rates. Then the mold is closed, which presses the fibers into the resin.
"The demand for this technology has been very high since it was first presented at K 2013. We held a number of intense discussions even then, with OEMs and suppliers who wanted to use the process for mass production. Companies in the electric and electronic goods sectors are also showing a great deal of interest in the process", says Fries.
FiberForm process uses KraussMaffei injection-molding expertiseThe development of KraussMaffei FiberForm technology also focused on creating fully automated production lines and reproducible manufacturing processes with short cycle times. FiberForm is a multi-functional processing method that combines injection molding with thermoforming of composite sheets to further improve the strength of fiber-reinforced plastic parts. It can be used to make seat shells and backs, instrument panel supports, convertible-top compartments, side-impact protection components, technical parts for the engine bay and semi-structural components. This opens up infinite potential for functional integration and part design since FiberForm can be combined with almost all special processes.
In the FiberForm process, endless-fiber fabric or textiles impregnated with a thermoplastic matrix are firstly heated, then shaped in the injection mold and finally over molded. "This allows ribs to be added for extra stiffness and other functions to be integrated into the process. Since production fits seamlessly into an injection molding operation, the process is ideal for mass manufacturing lightweight structural components," explains Stefan Schierl, Development Engineer of Technology Development at KraussMaffei. Like injection molding, the FiberForm process is easy to automate and can be used in fully automated production with compact manufacturing cells.
The controls for an infrared heater to heat the composite sheets have already been fully integrated into the machine's control system (MC6). As the machine's control system records important parameters, this enables the process and the quality of the parts made to be monitored with ease. KraussMaffei also offers the option to preheat the materials using a paternoster-design convection oven. "This technology is distinguished by the fact that the temperature is distributed evenly over the entire surface and thickness of the material during processing, which is also gentle and energy-efficient," says Schierl. These excellent features are of great importance when manufacturing hollow components with localized reinforcements, for example, as they allow a much greater freedom of design.