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Why is additive manufacturing of NdFeB magnets studied

Published on 26 March 2021
To reduce the CO2 emissions, the increased use of electric vehicles (EV),  electric actuators and offshore wind turbines could be part of the solution. Permanent magnets (PM) are key components for high power density e-drives needed in increasing amounts in future. Over 90 % of EV-motors are permanent magnet motors, due to the high power density achievable in small volume. Furthermore, e-bikes, wind turbine generators and consumer electronics among others rely on permanent magnets. Neodymium Iron Boron (Nd-Fe-B) permanent magnets dominate the market as they exhibit the highest magnetic power density at room temperature. Nd-Fe-B permanent magnets contain approximately 30 wt-% of Nd, Pr and Dy (rarely Tb), classified as critical raw materials (CRM) by the EU. The supply of these rare earth elements is controlled almost exclusively by China. 

It is a known fact that the raw material prices for Nd and Dy are subject to high price volatility, as evidenced during the 2011 rare-earth crisis. Heavy reliance on CRMs is a severe cost, availability and sustainability issue for e-drives based on permanent magnet technology. Considering the average rare earth metal content in an EV motor is 1.3 kg, the raw material costs of the magnets reaches up to 50% of the total raw material costs of the motor. 

The Nd-Fe-B magnets for EV drives or other motor applications are typically produced in a powder-metallurgical sintering route, which is the most cost efficient one for high grade anisotropic magnets that can be operated up to 200°C without suffering demagnetization. The drawback of this process is the limitation of available shapes, minimum sizes and huge amounts of wastes produced by cutting and shaping. A second route is the hot deformation technique typically resulting in cylindershaped magnets. Both methods start with fine grained powders of a few microns grain size demanding a careful handling in controlled atmospheric conditions in avoidance of oxidation. 

Thus, a route offering near net-shape production of Nd-Fe-B magnets with the use of less dangerous powder fractions of around 30-40 microns mean grain size like the Laser Powder Bed Fusion (L-PBF) process offers many advantages to produce a new design of efficient permanent magnet containing electric drives, actuators or sensors. 3DREMAG targets the establishment of this specific processing by providing starting powders to allow additive manufacturing (AM) experts to work with permanent magnet powders and vice versa. Thus, the 3DREMAG consortium was gathered in such a way to cover the whole process chain from pre-alloy and raw powder production, to particle plasma spheroidization and L-PBF. This will allow to test the applicability and learn about the processing parameters, in order to finally commercialize a powder after the end of the project.