REProMag

Magnets that don’t cost the earth Rare earth magnets play a crucial role in many everyday applications, yet Europe does not currently enjoy an independent supply of the materials used in production, leading researchers to investigate how existing resources can be used more efficiently. We spoke to Professor Carlo Burkhardt about the REProMag project’s work in developing a new processing route The strongest type of magnets currently available, rare earth (RE) magnets are used in a wide range of everyday applications, including medical devices, motors and various consumer electronics devices, and demand is correspondingly high. There is typically a choice here between either samarium-cobalt magnets, which are relatively expensive, or neodymium-ironboron magnets. “Both these types of magnets are based on a rare earth material.

However, when people talk about rare earth magnets, they’re usually talking about neodymium-iron-boron magnets,” outlines Professor Carlo Burkhardt, the coordinator of the REProMag project. These magnets are integral to many high-tech industries, in particular electro-mobility, electronics and wind energy, yet Europe is largely dependent on external sources of RE metals, leading Professor Burkhardt and his colleagues in the REProMag project to look at how existing resources could be used more efficiently. “The main idea is to develop a closed material loop and to reuse the waste material that’s currently available in the EU, so that we can then gain a greater degree of independence in supply,” he says.

Rare earth metals This starts with recycling existing RE metals, building on the work of the REMANENCE project in developing new processes to recover these materials, with researchers looking primarily at hard disc drives as a source. Recovering RE metals from hard disc drives is a complex task however, as when subjected to conventional recycling methods the magnet will shatter and stick to other bits of metal, so the project is instead using a different approach. “The magnet is separated as completely as possible from the electronic

device, but it doesn’t have to be detached completely, because we then do a hydrogen treatment in a closed vessel,” explains Professor Burkhardt. This treatment can be compared to the effect of ice forming on a road in winter. “The ice has a larger volume than the water, and causes cracks in the road. Something similar happens in a magnet with this hydrogen treatment,” says Professor Burkhardt. “Neodymium forms a hydride, which causes volume expansion – so this cracks the material apart and breaks it into powder. The electronic component is introduced into this vessel with hydrogen, and the magnet breaks up into a powder.”

This represents a relatively easy way of separating the magnet from the other components in a hard disc drive, which can then be re-cycled in the conventional manner, while researchers can look to use the re-cycled magnets in production. It’s important here to consider the composition of the magnet. “One big issue is the dysprosium content. Dysprosium is very expensive, as the majority of the supply is located in Southern China. Dysprosium is required if you want high temperature stability in a magnet. So if you want a magnet to operate at higher temperatures, like in an electrical motor for example, then you need a higher dysprosium content,” outlines Professor Burkhardt. These are important issues in terms of the circular economy and the eventual applicability of a re-cycled magnet, while Professor Burkhardt says there are also other factors to consider, including any corrosion on the magnet. “The more corroded a magnet the more oxidised the neodymium, and the worse the eventual performance of the recycled magnet,” he explains. “The addition of extra neodymium can help to restore the original performance.”

Shaping, debinding and sintering

REProMag M18 meeting at Sennheiser, Germany.

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The next step in the project is the development of a more efficient method for producing RE magnets. Current production routes are not always efficient in their use of

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RE metals, so Professor Burkhardt and his colleagues in the project are working to develop a new, waste-free route for the manufacturing of high specification permanent magnets, the Shaping, Debinding and Sintering (SDS) process. “The SDS process starts with a feedstock, which is a blend of the magnetic material and some polymers. This is effectively the starting material in the SDS process,” he outlines.

High-quality materials are used in the SDS process, a highly innovative, automated process that produces magnets without any waste. “The SDS process is designed for the production of small magnets, but in very large quantities,” continues Professor Burkhardt. “We have several commercial partners in the project, who hold deep expertise about the geometries of these magnets and their potential applications.

We cover the whole manufacturing chain, from the powder production, through to the production of the magnets.”

The SDS process boosts energy efficiency along the whole manufacturing chain, and can also be used to produce RE magnets in all kinds of sizes and shapes, which represents a significant development in terms of their wider applicability. Currently, these RE magnets are only available in conventional shapes, as they are very difficult to manufacture and it’s extremely expensive to grind them afterwards into a specific shape, which affects the ways in which they are used. “Today, applications are often built around the geometry of the magnet - companies may build their specific application around a certain shape of magnet. If the magnet could be in another shape, for example in a U profile, then this could open up other commercial applications,” says Professor Burkhardt. The project is developing new methods to shape these magnets, which could open up the possibility of using them in further potential applications in future. “This could be very interesting, particularly with respect to very small magnets. We’ve been looking at miniaturisation, and the development of very tiny magnets, which could be directly shaped,” outlines Professor Burkhardt.

Feedstock development.

Microstructural analysis.

Production of recycled magnets.

Commercial marketplace This approach helps to ensure that research is relevant to the wider commercial marketplace, which is a key part of the project’s overall agenda. This takes on even greater importance given the high level of demand from industry for RE magnets, which Professor Burkhardt says is set to rise even further in future.

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At a glance Full Project Title Resource Efficient Production Route for Rare Earth Magnets (REProMag) Project Objectives REProMag is a European project, financed by the European Commission under the call programme ‘Factories of the Future.’

The project was presented under the topic FoF-02-2014: Manufacturing processes for complex structures and geometries with efficient use of materials.

Project Funding Project funded by the European Union’s Horizon 2020 research and innovation programme under Grant Agreement no 636881.

Project Partners • OBE Ohnmacht & Baumgärtner GmbH & Co. KG (Ispringen, Germany) – REProMag Coordinator. • FOTEC Forschungs- und Technologietransfer GmbH (Wiener Neustadt, Austria). • PT+A GmbH (Dresden, Germany). • HAGE Sondermaschinenbau GmbH & Co KG (Obdach, Austria). • Lithoz GmbH (Vienna, Austria). • TEKS SARL LTD (France and the UK). • SIEMENS AG (Munich, Germany) • Sennheiser electronic GmbH & Co. KG (Wedemark, Germany) • Vienna University of Technology (Vienna, Austria). • University of Birmingham (Birmingham, UK). • Montanuniversitaet Leoben (Leoben, Austria). • Jožef Stefan Institute (Ljubljana, Slovenia). • NPL Management Limited (Teddington, UK). • Steinbeis 2i GmbH (Karlsruhe, Germany).

Contact Details Head of Technology & Innovation, Professor Carlo Burkhardt OBE Ohnmacht & Baumgärtner GmbH & Co. KG Turnstraße 22 75122 Ispringen Germany T: +49 7231 802215 E: CBurkhardt@obe.de W: www.repromag-project.eu

Professor Carlo Burkhardt

Carlo Burkhardt is professor for manufacturing technology and head of the institute for material development and testing (STI) at Pforzheim University (Germany). Previously he worked as head of development at Witzenmann GmbH, a German automotive supplier with 4.000 employees, and he has also held other roles in both the public and private sectors.

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Processing parameter studies.

“Take a conventional car for instance – about 50 years ago there were relatively few permanent magnets in a car, but these days the Mercedes S-class has 200 electric motors, for things like seat adjustment, windows, rear mirrors and light controls.

Then we see that more and more consumer electronic devices have electrical motors,” he points out. There is a correspondingly high level of demand for these RE metals, yet the supply is currently strategically controlled by China, which has important implications for European industry. “The RE metals are rated very highly in the critical materials strategy of the EU, as electro-mobility, wind energy, kinetic energy, electronics – industry 4.0 as we call it – is not thinkable without RE magnets,” says Professor Burkhardt.

Development of sds processing technology. magnets. “We have to achieve certain standards.

Neodymium-iron-boron magnets were first developed in 1982, and over the years they have been quite rapidly optimised,” he outlines.

This remains an active area of research, yet the focus within the project is more on the SDS processing route and using resources more efficiently. While hard discs are the main current source of RE metals there are also many others to consider, and Professor Burkhardt has identified three in particular. “In future we will be able to gain large quantities of RE metals from hybrid cars, electric cars and wind turbines,” he outlines. The REProMag project will conclude towards the end of 2017, yet Professor Burkhardt plans to pursue further research in this area in

We have several commercial partners in the project, who hold deep expertise about the geometries of these magnets and their potential applications. We cover the whole manufacturing chain, from the powder production, through to the production of the magnets A more reliable, independent supply of these metals is therefore central to commercial development, while there are also environmental considerations to take into account. The chemical separation methods currently used in RE metal extraction are not very environmentally friendly, and carry a risk of soil contamination, underlining the wider importance of developing a more sustainable process. “Recycling makes a lot of environmental sense in terms of goals around the circular economy, even without the pressure on the material supply side,” stresses Professor Burkhardt.

While recycling is central to efforts to improve sustainability, quality standards still have to maintained, so in future Professor Burkhardt says researchers will look both at using resources more efficiently and developing stronger

future, with a view to demonstrating the technical feasibility of the SDS processing route. “We are currently applying for a further project, for upscaling production to larger quantities, while we are working together with customers on certain applications,” he says.

SDS processed NdFeB magnets.

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