“fusionCASTING” – Casting technique combining die casting with aluminum sheets and profiles for large body structures

In modern car body construction, in addition to weight reduction, the selection of material substitutes, their recyclability, and the processes used to minimize environmental impact play a central role. Aluminum (Al) has established itself as the most important car body material due to its low density, high specific strength, and high corrosion resistance. It is used in the form of both cast and wrought alloys.

The challenges in car body construction: sustainable, cost-effective, and safe

Since the introduction of GIGA casting of aluminum in the summer of 2020, previous ways of thinking and production methods in car body construction have been called into question worldwide. High investment costs and a lack of supplier infrastructure are preventing European car manufacturers from adopting this approach. In addition, vehicle structures made entirely of cast alloys cannot be manufactured with the same crash performance as structures made using conventional sheet metal construction with wrought alloy profiles. As a result, alternative technology routes for the production of large-format die-cast parts are currently becoming the focus of the automotive industry. However, Al-Al bonding poses a technical challenge due to the natural oxide layer of aluminum. 

The solution: new fusionCASTING manufacturing technology for large-scale aluminum car body structures

In order to develop an economical and efficient solution for car body construction, Fraunhofer IST and Fraunhofer IFAM are working on a novel manufacturing technology called fusionCASTING, which is intended to enable the casting-based connection of classic die-cast structures with sheet metal and profile construction. Aluminum sheets and profiles are used in crash-relevant or large-area areas because they offer high ductility, good crash performance, and high material quality while also having a low wall thickness. Aluminum die casting, on the other hand, is used where complex geometries or ribbed structures offer advantages. In order to achieve a material-locking bond, innovative oxidation protection coatings are being developed for the sheet metal surface.

The advantages of fusionCASTING for car body construction

FusionCASTING is intended to enable the use of conventional large die-casting machines with a clamping force of around 4,400 tons for the production of large, single-piece aluminum car body structures such as rear bodies or battery boxes. This avoids costly investments in new giga press casting systems. At the same time, cycle times are significantly reduced, material quality is ensured, and the risk of casting defects is reduced. In addition, the crash suitability and reparability of the overall structure are maintained. Overall, the project is intended to contribute to maintaining the competitiveness of the German automotive industry.

The project: FutureCarProduction

In the FutureCarProduction flagship project, fusionCASTING is being investigated as a potential Fraunhofer technology. The approach has high sustainability potential, among other things through the use of secondary material for large-format castings, an optimized repair concept, and overall leaner car body production. Experimentally generated data on the materials used and the energy requirements of the pretreatment and die-casting processes serve as input variables for evaluating the assessment methodology developed in the flagship project.

Funding body: Fraunhofer-Gesellschaft (Fraunhofer flagship project)