Carbon-fiber-reinforced plastics enable lightweight, high-strength bicycle components with complex hollow structures. In the “SmoothCarbon” research project, all ahead composites GmbH and the SKZ Plastics Center are developing a novel, reusable tube system designed to make manufacturing more efficient, more resource-efficient, and of higher quality. The goal is to produce components with a smooth inner surface while significantly reducing material consumption and process costs.

As part of the “SmoothCarbon” research project, all ahead composites GmbH and the SKZ Plastics Center are developing a novel, reusable tubing system. (Photo: AI-generated/all ahead composites GmbH)

SKZ and all ahead composites Launch Joint Research Project

Carbon-fiber-reinforced plastics (CFRP) enable the production of components that are exceptionally lightweight yet highly durable. Due to their outstanding mechanical properties, they are used in a variety of fields, including sports and recreation, aerospace, and robotics. In bicycle manufacturing, CFRP materials offer significant advantages, as they enable the creation of complex, weight-optimized hollow structures with high stiffness.

High Manufacturing Costs with Existing Methods
However, the production of such CFRP components presents several challenges. So-called polyamide bladders are frequently used to manufacture hollow structures; these support the shaping process through internal pressure during curing in the autoclave. Since the bladders used to date cannot expand, they must be laboriously positioned—sometimes multiple times—inside the components. This leads to long processing times and can cause irregularities on the inner surfaces of the hollow structures. Furthermore, the bladders are often damaged during subsequent manual removal, making reuse generally impossible. This results in high material consumption and additional costs.

In the “SmoothCarbon” research project, all ahead composites GmbH and SKZ are jointly tackling this challenge. The goal is to develop a novel, reusable tubing system for the resource-efficient and effective production of CFRP bicycle components with complex hollow structures.

Development of a Reusable Tubing System
At the heart of “SmoothCarbon” is the development of a specially adapted tube whose geometry corresponds as precisely as possible to the future inner contour of the CFRP component. This is intended to enable uniform pressure distribution during the curing process while simultaneously achieving a smooth inner surface free of disruptive wrinkles or irregularities. Because the tube is designed to closely match the final contour, the multiple layups previously required within the hollow structure are no longer necessary. This is expected to reduce layup time by approximately 75% and significantly lower the risk of manufacturing defects.

No compromise on build quality
Another focus is on the development of a novel tube material capable of withstanding the high thermal, mechanical, and chemical stresses encountered during CFRP processing. The goal is to enable the tube to be reused multiple times without compromising component quality. This is expected to reduce the material and energy requirements for manufacturing the single-use bladders used to date by more than 80%. In addition, an innovative welding process is being developed that allows even complex tube geometries to be manufactured without disruptive weld seams compromising the surface quality of the CFRP components.

Within the joint research project, all ahead composites GmbH is responsible for developing suitable laying and demolding processes, as well as a process for the automated production of tube geometries that closely match the final contours. At SKZ, the focus is on developing a suitable material formulation as well as designing and optimizing the manufacturing process for the novel tubes.

With this research project, we aim to make the production of complex CFRP components not only more efficient but also significantly more sustainable. By developing reusable tube systems, we aim to reduce material consumption, simplify manufacturing processes, and simultaneously improve component quality.
“We look forward to working with our project partner, all ahead composites, to develop innovative solutions for CFRP processing,” explains Thomas Zimmermann, project manager at SKZ.

Funding
SmoothCarbon (FK: 16KN097728) is funded by the Central Innovation Program for SMEs (ZIM) on behalf of the Federal Ministry for Economic Affairs and Energy (BMWE).