Manufacturing innovation set to take the 'rare' out of rare-earth magnets
Although rare-earth magnets are vital to many modern devices, from cell phones and electric cars to hospital equipment and wind turbines, few of these essential metal alloys are produced in Europe. An EU-funded consortium is revolutionising production, enabling these super-strong permanent magnets to be fully recycled and manufactured sustainably.
© OBE Ohnmacht & Baumgartner
The REProMag project has developed and validated a process which is nearly commercially ready and will substantially increase sustainability in the production of rare-earth magnetic components by using 100 % recycled metals. The goal is to reduce material use by as much as 40 % and increase energy efficiency along the entire manufacturing chain by over 30 % compared to conventional production processes.
Products that rely on rare-earth magnets are an integral part of modern life in Europe, but Europe remains highly dependent on imports to meet demand: currently, 80 % of rare-earth metals are produced in China. As such, the European Commission has recognised rare-earth magnetic materials as having the highest supply risk of all rare materials crucial to EU manufacturing, says Professor Carlo Burkhardt at REProMag coordinating partner OBE in Germany.
The REProMag partners, including several manufacturing SMEs, are therefore implementing novel zero-waste processes to enable rare-earth metals, such as neodymium and dysprosium, to be recycled within Europe for precision-manufactured magnetic components.
The key achievement is the development of a new integrated manufacturing solution for rare-earth magnets based on shaping, debinding and sintering, or SDS. It uses innovative technologies to avoid material contamination and to maintain or even improve the properties of the finished magnet.
In a first stage, rare-earth materials extracted from discarded devices and components are recycled into metallic powder which is then transformed into pellets with a polymer binding. These pellets can be used in specialised injection-moulding processes or in a 3D printing system developed by the REProMag partners which ensures accurate alignment of the magnetic fields in the finished product.
Rather than machining magnets from bulk metal blocks, injection moulding and 3D printing enables magnets to be made precisely for their intended application. They may be used for tiny components in hard-disk drives and audio headsets or at the much larger scale required for the powerful motors in electric vehicles and generators in wind turbines.
This so-called net-shape production process equates to zero-waste production with no material discarded, substantially reducing resource consumption. Crucially, it also mitigates the environmental impact of the rare-earth industry, which currently relies on intensive and hazardous mining and metal-processing techniques.
Society will benefit from this development, as the consumption of energy and hazardous chemicals in the exploitation of rare-earth materials from metal ore will be considerably reduced, Burkhardt says.
In the REProMag manufacturing chain, the moulded or printed magnets undergo a debinding process to remove the polymer binder and a subsequent sintering process to increase their density and mechanical strength before a special coating is applied to prevent corrosion.
As there is no additional post-processing, the REProMag approach cuts energy consumption by at least 30 % compared to machining magnets from bulk stock. Further refinements of the production methods currently being researched by the project partners could result in a 10 % to 40 % increase in the strength of the magnets themselves, enhancing the use of complex and 3D structured parts in miniature applications.
With the net-shape process assuring lower material consumption in the manufacture of complex and miniaturised parts, European industries will be able to offer more sustainable eco-friendly products, according to the REProMag team.
For context, a standard combustion-engine car might use as much as a kilo of rare-earth magnets in different components, while electric vehicles use up to 30 kilos in electric motor parts and a wind turbine might require as much as two tonnes.
At the end of their service life, the magnets can be recycled and re-enter the SDS processing cycle, Burkhardt says. The product life cycle goes from recycling to recycling, constituting a closed material loop within Europe that reduces dependency on imported resources and increases the competitiveness of local industries.