Researchers in Germany have set out to reinvent one of the most familiar parts of modern vehicles, the aluminum wheel, by developing a pioneering alloy that uses 30 percent recycled metal.
The novel alloy, developed at the Dortmund University of Applied Sciences and Arts (FH Dortmund), is expected to significantly reduce the carbon emissions of aluminum wheels without compromising their performance or design.
Led by the university’s Faculty of Mechanical Engineering, the innovative SUPA-Wheel project addresses the high energy costs associated with aluminum production. This is one of the automotive industry’s greatest sustainability challenges.
“We are developing the perfect alloy for the wheel,” Wilhelm Harms, a research assistant at the faculty who’s driving the project forward with his team, revealed. “Waste aluminum has a 10 times better CO2 balance than new aluminum.”
Low carbon alloy
Traditional wheels are made entirely from new aluminum (Al) as this pure material makes it easier to achieve the desired alloy composition. However, the reliance on new aluminum comes at a heavy environmental cost.
The reason for this is that producing new aluminum is extremely energy-intensive and carbon-heavy. To refine raw aluminum from bauxite ore, producers must first extract alumina and then use the electrolysis process.
This process requires large amounts of power, which is often generated from fossil fuels. Simply put, every ton of primary aluminum emits approximately 15 tons of CO2, depending on the energy source.
Credit: Fachhochschule Dortmund/Vincent Beringhoff
In contrast, recycled aluminum requires only about five percent of that energy, as it’s melted and remolded rather than extracted from ore. However, since recycled aluminum already contains small traces of other elements, the alloy’s sensitive composition becomes unstable.
The precise ratio of ingredients determines the hardness, strength, and corrosion resistance of aluminum wheels. This is why Harms and his team began exploring how to safely integrate secondary aluminum into wheel manufacturing without compromising quality.
The project brought together experts from wheel maker Borbet, the Fraunhofer Institute for Casting, Composite and Processing Technology (IGCV), aluminum producer Trimet Aluminium and plastics specialist Jordan Spritzgusstechnik.
Eco-friendly wheel design
FH Dortmund’s consortium and partners explored how recycled alloys can match the performance of new materials while reducing CO2 emissions. They also analyzed how far they could adjust the composition without compromising safety, and tested a total of 300 alloys and samples in the university’s chemistry laboratory.
Using this data, they created a predictive model to fine-tune the alloy’s recipe. It helped maintain stability even with a higher share of scrap metal. “First of all, we needed a model with which we could reliably predict the properties of new alloys and react to the effects of inclusions of other elements in the old aluminum,” Harms said.
Jakob Nowak, a research assistant working on the project, believes the effort is worthwhile. “The separation and sorting process is complex and so far only 30 percent recycled aluminum can be guaranteed as a stable supply quantity,” he stated in a press release.
Still, material recycling is just part of the project’s sustainability strategy. The team is also exploring structural and aerodynamic enhancements to reduce energy consumption further. “This saves fuel or electricity and therefore increases the range,” Nowak said.
A stronger alloy could enable the manufacture of thinner wheels, thereby reducing weight and enhancing energy efficiency. The scientists are also testing biogenic plastic inserts, which are aerodynamic hubcaps that reduce drag and extend the range of electric vehicles.
“An aluminum wheel – CO2-reduced, more cost-effective, but also stylish and saleable,” Wilhelm Harms, concluded. A prototype is expected by the end of the project, which runs until mid-next year.