The shiny aluminum wheel - also known colloquially as an aluminum rim - looks chic, but has a rather poor environmental footprint. A team of researchers from Dortmund University of Applied Sciences and Arts is working with project partners from Business Studies to reduce the CO2 emissions of aluminum wheels. In the "SUPA-Wheel" project, they are not only focusing on production, but also on the impact on fuel consumption.
The engineers' goal is ambitious. The SUPA-Wheel should form a harmonious triad: meeting ecological, technical and also Business Studies requirements. As a wheel manufacturer with several production sites in Germany, Borbet has to manage this balancing act time and time again. It is one of several project partners. Together, they support the researchers with market knowledge, manufacturing expertise and research materials. "And we are developing the perfect alloy for the wheel," says Wilhelm Harms. He and his colleague Jakob Nowak are research assistants at the Faculty of Mechanical Engineering at Fachhochschule Dortmund and are driving the research forward together with two assistants. In future, 30 percent scrap aluminum is to be used in their bikes. It sounds so simple.
But until now, wheels have been made from 100 percent new aluminum. It is easier to obtain the desired alloy for the wheel with this pure material. An alloy is a material that consists of at least two elements. In addition to aluminum, the wheel also contains silicon, iron, zinc, copper, magnesium and manganese. It is this finely tuned and time-tested mixture of elements that determines the hardness, strength and corrosion rate of aluminum wheels. However, recycled aluminum already contains tiny inclusions of other elements. And so the sensitive mixing ratio becomes unstable.
300 samples analyzed
The consortium of FH and the project partners therefore investigated what leeway exists in the alloy "without jeopardizing the safety of the bike", as Jakob Nowak emphasizes. To this end, test alloys and 300 samples were examined in the university's own chemistry laboratory. "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," explains Wilhelm Harms. The material tests are currently being carried out on the test benches at the University of Applied Sciences.
The engineers are convinced that the effort is worthwhile. "Waste aluminum has a ten times better CO2 balance than new aluminum," says Wilhelm Harms. So why only 30 percent used aluminum in the new wheel? "The separation and sorting process is complex and so far only 30 percent recycled aluminum can be guaranteed as a stable supply quantity," explains Jakob Nowak.
That's why engineers are looking for further CO2-saving potential in the wheel in addition to production with old aluminum. A higher strength of the aluminum alloy could make the same stability possible while using less material. This would make the wheels lighter and save energy if less mass has to be moved. Ideas for more modern hubcaps, so-called inserts, are well advanced. These plastic covers are clamped into the wheel to improve aerodynamics. "This saves fuel or electricity and therefore increases the range," says Jakob Nowak. When it comes to plastics, the engineers have opted for biogenic plastics without glass fiber reinforcement in line with the sustainability concept. Glass fiber is considered hazardous waste that cannot be processed or recycled for energy without great effort, which is why it is usually disposed of in landfills.
At the end of the project, a prototype solution should be available: "An aluminum wheel - CO2-reduced, more cost-effective, but also stylish and saleable," says Wilhelm Harms. The project will run until the middle of next year.
Background
The "SUPA-Wheel" project, headed by Prof. Dr. Matthias Müller, is being funded by the Federal Ministry of Business Studies and Climate Protection with a good half a million euros. Prof. Müller is in charge of the Laboratory for Fiber Composite Technology and Structural Mechanics at the Faculty of Mechanical Engineering. Prof. Dr.-Ing. Yves Rosefort, who teaches and researches vehicle drives at the faculty, is also involved. Project partners are the wheel manufacturer Borbet from Hallenberg-Hesborn (Sauerland), the Fraunhofer Institute for Casting, Composite and Processing Technology IGCV, the plastics processor Jordan Spritzgusstechnik from Menden and the manufacturer Trimet Aluminium from Essen.