The US Department of Energy’s Pacific Northwest National Laboratory, in collaboration with mobility technology company Magna, developed a manufacturing process that reduces more than 50% of the embodied energy and more than 90% of the carbon dioxide emissions used for collecting and transforming scrap aluminum into new vehicle parts.
In a media statement, the organizations said the patented Shear Assisted Processing and Extrusion (ShAPE) process collects scrap bits and leftover aluminum trimmings from automotive manufacturing and transforms it directly into suitable material for new car parts. It is also being scaled to make lightweight aluminum parts for EVs.
The most recent advancement, described in detail in a Manufacturing Letters research article, eliminates the need to add newly mined aluminum to the material before using it for new parts. By reducing the cost of recycling aluminum, manufacturers may be able to reduce the overall cost of aluminum components, better enabling them to replace steel.
“We showed that aluminum parts formed with the ShAPE process meet automotive industry standards for strength and energy absorption,” lead researcher Scott Whalen said. “The key is that the ShAPE process breaks up metal impurities in the scrap without requiring an energy-intensive heat treatment step. This alone saves considerable time and introduces new efficiencies.”
The publication marks the culmination of a four-year partnership with Magna, the largest manufacturer of auto parts in North America.
According to Whalen, besides steel, aluminum is the most used material in the auto industry. The advantageous properties of aluminum make it an attractive automotive component. Lighter and strong, aluminum is a key material in the strategy to make lightweight vehicles for improved efficiency, be it by extending the range of an EV or reducing the battery capacity size. While the automotive industry currently does recycle most of its aluminum, it routinely adds newly mined primary aluminum to it before reusing it, to dilute impurities.
Metals manufacturers also rely on a century-old process of pre-heating bricks, or “billets” as they are known in the industry, to temperatures over 1,000°F (550°C) for many hours. The pre-heating step dissolves clusters of impurities such as silicon, magnesium or iron in the raw metal and distributes them uniformly in the billet through a process known as homogenization.
By contrast, the ShAPE process accomplishes the same homogenization step in less than a second and then transforms the solid aluminum into a finished product in a matter of minutes with no pre-heating step required.
“With our partners at Magna, we have reached a critical milestone in the evolution of the ShAPE process,” Whalen said. “We have shown its versatility by creating square, trapezoidal and multi-cell parts that all meet quality benchmarks for strength and ductility.”
For these experiments, the research team worked with an aluminum alloy known as 6063, or architectural aluminum. This alloy is used for a variety of automotive components, such as engine cradles, bumper assemblies, frame rails and exterior trim.
The PNNL group examined the extruded shapes using scanning electron microscopy and electron backscatter diffraction, which creates an image of the placement and microstructure of each metal particle within the finished product.
The results showed that the ShAPE products are uniformly strong and lack manufacturing defects that could cause parts failure. In particular, the products had no signs of the large clusters of metal—impurities that can cause material deterioration and that have hampered efforts to use secondary recycled aluminum to make new products.
The research team is now examining even higher-strength aluminum alloys typically used in battery enclosures for electric vehicles.
“This innovation is only the first step toward creating a circular economy for recycled aluminum in manufacturing,” Whalen said. “We are now working on including post-consumer waste streams, which could create a whole new market for secondary aluminum scrap.”