A Beautiful Sky
Seamless aesthetics: Our plastic roof cross member marks the end of the magnesium era in convertibles. For an even more beautiful interior.
A quiet “click” and the convertible top locks into the windshield frame. Sun and rain stay outside. Now only the unsightly plastic cover for the locking mechanism mounted on the roof cross member remains disturbing.
A design update was therefore required for these systems. At the same time, weight and cost are saved.
Seamless headliner
The result is the first fabric convertible top with a continuous headliner all the way to the windshield. For this purpose, we replaced the previously common magnesium construction with lightweight high-performance plastics from our partner Envalior. This creates an interior that appears more premium and more harmonious. Exactly what the German premium manufacturer was looking for its new convertible model.
But the system without magnesium is not only more beautiful. It is also 700 grams lighter, consists of half the number of components and costs 20 percent less.
All in one step
In addition, all the advantages that a plastic base offers come into play. Numerous functions can be integrated into the component. These include, for example, openings, fastening elements, mounts and guides. The cross member also accommodates the actuators and the kinematics with which the top is locked and opened.
This is made possible by a hybrid molding process in which fiber-reinforced composite material is overmolded. This happens in only one process step, with one tool and completely without reworking. This range of performance would hardly be possible with the conventional construction made of magnesium.
The convertible system is only the beginning
It is remarkable that the roof cross member meets all automotive standards for crash safety despite the omission of magnesium. This also applies to the strict requirements for the interior. At the same time, it is particularly sustainable thanks to recyclable materials.
Together with Mercedes-Benz and Envalior, Röchling Automotive won the SPE Grand Innovation Award 2025 with the lightweight roof cross member. The cooperation is also a finalist for the JEC Innovation Awards 2025.
The development work on this system extends far beyond the roof cross member. In the future, other components will also benefit from the know-how gained through the cooperation. Röchling Automotive is already working on several prototypes with a further improved interaction of hybrid molding and high-performance plastics.
