RAILS – Recycling-based application of innovative lightweight structures in rail transport

Limitations of existing material systems and manufacturing processes

Particularly in the section of continuous manufacturing processes such as pultrusion, there is currently a lack of robust and industrially scalable solutions for the use of recycled materials. Thermoset composites make reuse difficult at the end of the product life cycle, while thermoplastic systems with recycled materials can only be used with limited process reliability. This gap hinders the implementation of a true circular economy in the composite industry.

Thermoplastic pultrusion with recycled materials as an innovative approach

This is where the RAILS research project comes in. The aim is to develop a thermoplastic pultrusion process that enables the use of recycled fiber and matrix materials while meeting the high mechanical and quality requirements of industrial applications. The thermoplastic approach opens up new potential in terms of recyclability, formability, and reparability of the lightweight structures produced.

Target groups and project objectives

RAILS is primarily aimed at composite manufacturers who want to further develop their material and process strategies in the direction of Sustainability and the circular economy. It is particularly aimed at companies that want to use recycled materials in continuous, industrially relevant manufacturing processes.

As part of the project, a process-reliable and transferable thermoplastic pultrusion process is being developed and its industrial feasibility demonstrated by way of example. Rail transport serves as an application example to demonstrate the performance and scalability of the developed approach under realistic requirements.

Development of recycling-based material systems for pultrusion

The RAILS project systematically investigates recycling-based fiber and matrix materials for use in thermoplastic pultrusion. The focus is on selecting, characterizing, and combining suitable recycled materials that are both stable to process and have good performance. The aim is to define material systems that meet the requirements of continuous manufacturing processes while enabling a high proportion of recycled content.

Process development for thermoplastic pultrusion with recycled materials

A central focus of RAILS is the development of a stable and reproducible thermoplastic pultrusion process for recycled materials. To this end, process parameters such as temperature control, impregnation, consolidation, and draw-off are specifically adjusted and optimized. Particular attention is paid to process stability and scalability in order to ensure industrial transferability.

Manufacture of sustainable lightweight composite structures

Sustainable lightweight composite structures are manufactured on the basis of the developed material and process concepts. These are used to evaluate mechanical performance, component quality, and process robustness. The extent to which recycled materials enable comparable or new application-relevant properties compared to conventional systems is investigated.

Application-oriented demonstration using rail transport as a technology carrier

Rail transport is used as an exemplary field of application to validate the developed solutions. The manufacture and evaluation of a technology carrier makes it possible to map real requirements for structural components and demonstrate the industrial applicability of the developed thermoplastic pultrusion processes in an industrial environment.

Transferability to other industries and composite manufacturers

An essential aspect of RAILS is the transferability of the results beyond the specific application. The materials and process approaches developed should be usable by composite manufacturers across all industries. In this way, the project contributes to the widespread establishment of sustainable, recycling-based manufacturing processes in the composite industry.

RAILS was launched in November 2025 and is currently in the early project phase. The focus is currently on detailing the material and process requirements and on initial investigations into recycling-based fiber and matrix materials. At the same time, the fundamentals for the design and adaptation of the thermoplastic pultrusion process are being developed. In the coming project phases, the developed material systems will be gradually integrated into the pultrusion process, process parameters will be optimized, and sustainable lightweight composite structures will be manufactured and evaluated. The goal is a robust, industrially transferable process solution for composite manufacturers with a focus on sustainability and the circular economy.

RAILS is being implemented in close cooperation between the partners involved, who contribute different areas of expertise along the process chain. Autenrieth is responsible for the functional integration of the pultruded profiles in injection molding. BWF is developing recycling-based aramid fleece and working on the further development of thermoplastic pultrusion for more complex profile geometries as well as on the ecological evaluation within the framework of life cycle analyses. Reese is responsible for the continuous forming of the pultrudates and the bending of rod structures. Wagenfelder develops pultrusion-capable yarns from recycled carbon fibers. CIKONI supports the project with simulation-based methods for process and component design.

The project is embedded in Fraunhofer IGCV's research activities in the field of thermoplastic pultrusion and builds on experience gained in related Fraunhofer IGCV projects such as DRIFT and MaTCH, which are also developing innovative thermoplastic pultrusion processes. In addition, there are content-related interfaces with the work of the Fraunhofer IGCV's Recycling department, whose projects offer the prospect of further synergies in the field of recycling-based material and process development.