New milestones in lightweight construction: Towpregrod reaches finish line

On the path to an emission-free and sustainable future, high-performance fibre composite materials such as Carbon Fibre Reinforced Plastics (CFRP) contribute significantly to the efficient use of resources. Together with Schütze GmbH, the Institute of Production Engineering and Machine Tools (IFW) is researching and developing a flexible process chain for the continuous production of CFRP sandwich rods for the aerospace industry. Towpregrod is now nearing successful completion with the commissioning of the pre-series plant.

Commercially available CFRP profiles are usually manufactured using pultrusion. The dry rovings or semi-finished fibre products pass through a resin bath and then cure as they pass through a heated mould. The tooling costs involved limit the process primarily to medium and large series production. In addition, pultrusion processes often only allow fibre deposition in the direction of pull. Together with IFW, Schütze GmbH has developed a novel tool-free process chain for the continuous production of CFRP sandwich rods from pre-impregnated semi-finished products.

From prototype to pre-series

Since the successful launch of the prototype in November 2024, the project has made some serious progress. The multi-orbital lay-up unit developed by IFW was replicated at Schütze’s production site and equipped with several targeted optimisations. The resulting pre-series system was successfully put into operation during the latest series of tests, and several rod samples were produced.

The system, consisting of two counter-rotating orbital carriers, each with up to 12 lay-up units, continuously lays pre-impregnated fibre bundles over the entire surface of the unidirectionally reinforced rod. Diameters from 15 mm to 80 mm and angular positions between 30° and 85° can be achieved.

Another milestone was achieved with the testing of new curing cycles. These are the result of a parameter study conducted previously, in which various temperature-time profiles were systematically investigated. The researchers expect the optimised curing cycles to improve component quality.

Final testing and process validation

With one month remaining, the project is now in its final stages. All key project objectives have been achieved: the development, commissioning, and process research of the production system, successful duplication with process optimisations, and the production of rod samples in various configurations. All that remains is the final mechanical characterisation of the last rod samples produced in order to finally validate the optimised process parameters and quantify their influence.

The tool-free, continuous production of CFRP sandwich rods with individually adjustable properties opens up new possibilities for the aerospace industry and mechanical engineering. The technology developed in the project enables economical production even in small series and thus contributes to expanding the range of applications for lightweight CFRP components.

The Institute of Production Engineering and Machine Tools (IFW) will be present at JEC World 2026, in Hall 6, booth D119.

Cover photo: Image from continuous CFRP sandwich rod production