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At the EmpowerAX InnovationLab, the DLR Institute of Lightweight Systems (Braunschweig, Germany) has worked together with partners from research and industry domains to explore how additive extrusion with continuous fiber reinforcement can be industrialized across various application areas — from aerospace to mobility. The focus has been on the entire process chain, from filament production and printing to the functionally integrated lightweight structure. CW published an overview of the EmpowerAX open platform in 2023.

Building directly on these findings, DLR is actively pursuing the SchallFTP project, which aims to apply a sonic infusion cell for the impregnation and manufacture of fiber-reinforced thermoplastic semi-finished products — such as filaments — in an industrial context. A key area of the project is the advancement of circular economy principles within additive manufacturing. Central to this is the question of how fiber waste can be transformed into new, pseudo continuously reinforced 3D printing filaments in a resource-efficient, cost-effective way with strong application potential.

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One thing is clear: carbon fiber-reinforced plastics (CFRP) retain significant material value, even at the end of their service life. Landfilling such materials is not only environmentally questionable but also heavily restricted by EU legislation (1999/31/EC). Against this backdrop, DLR is developing a process within the SchallFTP project that will enable efficient recycling of production waste and reject components into high-quality filaments for fiber-reinforced 3D printing.

To achieve this, carbon fibers coming from production rejects and waste (rCF) are combined with high-performance thermoplastics (such as PPS) through a specially adapted impregnation process. This in-house method enables a fiber volume content of up to 50%, while maintaining minimal degradation, thus making the recycled fibers viable for industrial use. The resulting filaments offer comparable design freedom to those made with virgin carbon fibers (vCF), while significantly reducing both costs and resource consumption, the DLR reports. This makes them particularly attractive for non-load-bearing applications in aerospace, automotive and other mobility sectors, ranging from cabin components to structural parts in vehicle construction.

Illustration on the subject of rCF.

The DLR’s goal is to preserve the material value of rCF as much as possible, closing the loop in lightweight construction in a truly sustainable way. Future research will focus on the reliable processing of different recyclates, particularly regarding fiber quality, contamination and ageing. The objective is to establish robust, industry-ready processes that enable reproducible transformation of recycled fibers into new semi-finished products from filament to functional structure.

Thermoplastic matrix systems also play a key role here. Targeted use of these materials is expected to simplify and accelerate recycling processes. Supported by simulation methods and new quality standards, these efforts aim to boost industry confidence in the use of recycled fibers. In the long term, the DLR seeks to work closely with material producers and application industries to create a standardized, certifiable value chain for rCF-based products.

Insights into the latest developments in high-performance fiber recycling will be presented at the annual on Oct. 8, 2025 in Stade, Germany. The topic will be showcased as one of many exciting research focal points. Participating researchers look forward to engaging directly with attendees and jointly discussing the next steps toward a sustainable, circular fiber-processing future.