Manufacturing of Bio-Based Thermoplastic Fiber-Metal-Laminates Using a Novel Consolidation Process

Hybrid materials made of fiber-reinforced polymers (FRP) and metals offer great potential for a wide range of applications by synergistic combination of each material’s benefits. Compared to monolithic materials and traditional FRP, fiber-metal laminates (FML) can provide more versatile functionality, better insulation capability and higher weight-specific mechanical properties like impact strength and damage tolerance. However, the production of thermoplastic FML is currently based either on discontinuous manufacturing processes or resource-intensive impregnation presses. In addition, the combination of dissimilar materials results in difficult material separation or recycling. The Fraunhofer IPT has developed a continuous and resource-effective consolidation process to manufacture thermoplastic FML that are fully recyclable. During the impregnation and joining process, thin metal belts serve as tools for heat and pressure transfer, which finally form the top layers of the sandwich material. To achieve a strong bond between the core and top layers, a laser-based structuring process for metal surface treatment is used, eliminating the need for poorly recyclable bonding agents. This paper describes the developed process and compares it with traditional production methods. Experimental test results for flax-PLA based FML are presented to show the feasibility of the developed process and the potential for industrial applications.