A set of researchers at the Department of Energy’s Oak Ridge National Laboratory have proved that permanent magnets produced by additive manufacturing can outperform those that are traditionally made.
The AM process can also conserve critical materials that are otherwise wasted using traditional manufacturing methods.
Researchers fabricated isotropic, near-net-shape, neodymium-iron-boron (NdFeB) bonded magnets at DOE’s Manufacturing Demonstration Facility at ORNL using the Big Area Additive Manufacturing (BAAM) machine. The resulting product displayed comparable or better magnetic, mechanical and microstructural properties than bonded magnets made with traditional injection moulding with the same composition.
The additive manufacturing process began with composite pellets consisting of 65 volume percent isotropic NdFeB powder and 35 percent polyamide (Nylon-12) manufactured by Magnet Applications, Inc. They were then melted, compounded, and extruded layer-by-layer by BAAM into desired forms. All the while, no materials were wasted during the production process. Conventional sintered magnet manufacturing can result in between 30-50 percent material waste.
Using a process that conserves material, rather than waste it, is especially important in the creation of permanent magnets made with neodymium, dysprosium. NdFeB magnets are the most powerful on earth. They are used in a plethora of technology equipment, ranging from computer hard drives to electric vehicles and wind turbines.
In addition to conserving materials, the printing process is also able to produce complex shapes, requires no tooling and is faster than traditional injection methods.
“Manufacturing is changing rapidly, and a customer may need 50 different designs for the magnets they want to use,” said ORNL researcher and co-author Ling Ti. “Traditional injection moulding would require the expense of creating a new mould and tooling for each, but with additive manufacturing the forms can be crafted simply and quickly using computer-assisted design.”
Their future work will be exploring the printing of anisotropic, or directional, bonded magnets, which are stronger than isotropic magnets that have no preferred magnetisation direction. Researchers will also examine the effects of binder type, the loading fraction of magnetic powder, and processing temperature on the magnetic and mechanical properties of printed magnets.
Alex King, Director of the Critical Materials Institute, who funded the project, believes the research has big potential and makes a number of improvements on the traditional manufacturing methods.
“The ability to print high-strength magnets in complex shapes is a game changer for the design of efficient electric motors and generators,” King said. “It removes many of the restrictions imposed by today’s manufacturing methods.”
A co-author of the research, John Ormerod agreed, saying additive manufacturing could go on to play a role in the further development of other magnetic objects.
“This work has demonstrated the potential of AM to be applied to the fabrication of a wide range of magnetic materials and assemblies,” said Ormerod. “Magnet Application and many of our customers are excited to explore the commercial impact of this technology in the near future.”