Aluminum scraps left over from factories and old products could be given a valuable second life as an extremely lightweight material used in cars, buildings and machinery.
Researchers at Fraunhofer IWU in Germany are developing new ways to make aluminum foam using recycled aluminum instead of relying mainly on newly manufactured aluminum powder.
Their work could reduce energy use, manufacturing costs and carbon emissions while keeping valuable metal in circulation for longer.
Aluminum foam is a metal filled with many tiny air pockets, giving it a structure somewhat similar to a sponge. Despite being extremely light, it can absorb large amounts of energy and reduce vibrations.
These properties make aluminum foam useful in cars, industrial machinery, construction, rail transportation and other applications where engineers want to reduce weight without sacrificing performance.
However, there is a drawback. Aluminum foam is usually produced using fine aluminum alloy powders, and manufacturing these powders can be complicated, expensive and energy intensive.
The Fraunhofer researchers investigated whether aluminum waste could replace some or even all of this newly produced powder.
One promising source is aluminum chips created during manufacturing. Rather than treating these chips simply as waste, the researchers grind and sort clean chips made from a single aluminum alloy until they become a powder-like material.
Tests showed that this recycled material could be successfully processed into aluminum foam. Importantly, the resulting foam had structures and densities comparable to foam made using conventional aluminum powders.
Dr. Jörg Hohlfeld, head of the Metal Foam Group at Fraunhofer IWU, says returning production waste directly to the manufacturing cycle could provide significant environmental and economic benefits.
One major advantage comes from aluminum’s energy requirements. Producing new aluminum from raw materials requires enormous amounts of energy. Making secondary aluminum from existing metal requires far less, potentially reducing both carbon emissions and costs.
The researchers aren’t limiting their approach to small manufacturing chips. They have also investigated larger pieces of aluminum waste, including foil, coils and material from vehicle wheels.
These materials can be cut, crushed, ground and sieved until particles of the required size are produced. Even old aluminum foam components could potentially be broken down, sorted and turned into material for making new foam.
An especially interesting part of the research involves “solid-state recycling.” Traditional metal recycling often involves melting scrap completely before forming it into a new product. The Fraunhofer approach aims to process some aluminum without fully melting it.
Keeping more of the material in a solid state can reduce energy consumption and minimize the amount of metal lost during recycling.
The researchers say recycled aluminum particles could become a practical alternative to newly produced aluminum alloy powders, potentially making aluminum foam much more resource-efficient.
The next challenge is moving the technology toward large-scale industrial use. Scrap materials don’t always have exactly the same composition or quality, so researchers need to ensure the finished foam delivers reliable performance despite these differences.
The team also plans detailed studies of the technology’s environmental impact.
If those efforts succeed, yesterday’s aluminum wheels, factory scraps and other discarded metal could become tomorrow’s lightweight components—creating a more circular approach to manufacturing while reducing the need for energy-intensive new aluminum.
