A german research team aims to increase the use of recycled aluminium in production to at least 30 percent.
The automotive industry has changed in many respects over the past few decades. While steel rims were long considered the standard, aluminium has gained the upper hand since the 1990s due to its lightness and corrosion resistance. However, light alloy rims also have their drawbacks: they are now raising fundamental questions about sustainability and the utilisation of resources. Producing aluminium, in particular, is very energy-intensive and is the source of considerable CO2 emissions. Compared with crude steel, these emissions are even showing a tenfold increase. Therefore, researchers at the Fraunhofer Institute for Casting, Composite and Processing Technology (IGCV) are aiming to increase the proportion of recycled aluminium in production to at least 30 percent as part of the “Supa-Wheel” (Sustainable Production of Aluminium Wheels) project, which is funded by the German government.
“Together with our project partners, we want to significantly reduce the environmental impact and optimise the use of resources at the same time,” explains Robert Kleinhans, who works on innovative casting processes and materials at Fraunhofer IGCV in Garching. “For that reason, we’re exploring how we can make better use of recycled aluminium.” To do so, the researchers are pursuing the so-called cradle-to-cradle principle, a concept that is the epitome of sustainable design and production. Its objective is to minimise waste and use resources efficiently. Products are designed in such a way that they need not be disposed of as waste at the end of their service life, but are fully recyclable or biodegradable. The objective is to create closed loops. In practice, this means that old rims are not disposed of but reintegrated into the production process.
Setting quality standards for recycled aluminium
However, the challenges presented by the production of aluminium alloys using recycled materials are manifold. “Contamination can impair the strength and durability of the rims. When it comes to safety-relevant components, that is a no-go. It’s therefore crucial to precisely analyse the interactions among various elements in the alloy. That’s the only way we can ensure that the properties of the rims meet the automotive industry’s high quality standards.”
A “recipe” for rims made from recycled material One important component, therefore, is the development of a matrix comprising different aluminium alloys with varying element contents. This matrix helps researchers to understand the dependencies between the alloy components and the resulting material properties. “This systematic approach allows us to specifically develop alloys that are sustainable and yet retain optimum performance properties,” explains the scientist. “It’s comparable to a cake recipe. For example, the more copper an alloy has, the stronger it becomes. However, this also increases the risk of corrosion. “In the end, all the ‘ingredients’ have to be precisely harmonised.” This innovative methodology – for which the researchers have now applied for a patent – makes it possible to find the best combinations for the production of wheel rims or other components that are both ecologically and functionally convincing.
Lower costs for automakers
This is an approach that would also be economically worthwhile for car manufacturers. Production costs for secondary aluminium are significantly lower than those for primary aluminium, as only around 7 percent of the energy is required. Car manufacturers can achieve cost savings in addition, especially in the context of increasingly stringent regulations to promote decarbonisation. Robert Kleinhans therefore believes that there needs to be increased investment in modern sorting and recycling technologies in the long term. That is the only way to guarantee secondary aluminium that is purer and higher in quality and a necessary step if the market share of recycled aluminium is to be increased.
Source: Fraunhofer IGCV
