Composite profiles for automotive roof racks and boxes
Roof boxes and roof rack systems are expected to become lighter, stronger and easier to assemble while maintaining high structural performance and reduced vibration. Thermoplastic composite profiles can add value wherever structure, functionality and weight come together, whether as local reinforcements, integrated interfaces or lightweight hybrid cross members.
Composite profiles open up new design opportunities
Thermoplastic composite profiles can fulfil a wide range of functions in roof boxes and roof rack systems, from local structural reinforcement to integrated profile and interface solutions.
Today, roof boxes, roof rack systems and platform racks must do far more than simply provide additional cargo capacity. They need to be lightweight, durable, corrosion-resistant and easy to install. At the same time, increasing demands for functional integration, sustainability and efficient high-volume manufacturing continue to shape product development.
Thermoplastic composite profiles offer new possibilities for addressing these challenges. The key consideration is not whether the application is a roof box or a roof rack system, but rather the function within the component. Should a specific area be reinforced? Or should functions such as guidance, fastening, sealing or joining be integrated directly into the profile geometry?
Roof boxes: targeted reinforcement of thin-walled structures
Roof boxes are typically manufactured from thin-walled plastic shells. Areas exposed to particularly high loads include the base section, mounting points, hinges, locking mechanisms and the interfaces to the roof rack.
Pultruded continuous fibre-reinforced profiles can selectively increase the stiffness of these highly loaded areas without requiring the entire shell to become thicker or heavier. Extruded fibre-reinforced profiles complement this approach by integrating functions such as edge profiles, guide rails, sealing surfaces, mounting rails or locking features.
Which applications benefit most?
For roof rack systems and platform racks, load-carrying capacity, stiffness and long-term durability are key design requirements. At the same time, manufacturers seek modular designs that simplify assembly while integrating multiple functions.
Pultruded composite profiles can reinforce primary load paths, for example within crossbars, platform structures or local reinforcement elements. Extruded profiles can additionally integrate fastening grooves, adapter geometries, guide features, sealing areas and other functional interfaces directly into the profile.
Furthermore, thermoplastic fibre-reinforced profiles can contribute to vibration damping, helping reduce noise, peak loads and wear at critical interfaces.
The greatest design potential arises when structural performance, attachment concepts and functional integration are considered together—instead of simply replacing an existing metal profile with a composite equivalent.
Pultrusion or extrusion? The function determines the technology
Pultrusion is particularly suitable for load-path-oriented reinforcement where high stiffness and strength are required. Extrusion is the preferred technology for complex profile geometries with integrated functions such as guidance, fastening, sealing or joining.
Both technologies can provide significant advantages in roof boxes as well as roof rack systems. The appropriate solution depends on the specific function the profile must fulfil within the overall system.
Weight comparison: What is the Potential?
Current product developments demonstrate that significant weight savings can be achieved in roof boxes and roof rack systems through consistent material selection and design optimisation, while maintaining high structural performance and functionality.
Thermoplastic composite profiles can further enhance this approach by selectively reinforcing local load paths, integrating multiple functions into a single profile and enabling lightweight hybrid designs.