3D Magnetism

Researchers at the U.S. Dept. of Energy’s Oak Ridge National Laboratory (ORNL) in Tennessee have developed a 3D printing process to produce permanent magnets used in electric motors that is faster, less expensive and allows for more complex shapes than traditional bonded magnets.

Permanent magnets, which are used in motors and generators for electrified vehicles, computer hard drives and wind turbines, are made from pricey rare earth materials such as neodymium and dysprosium. While 30% to 50% of this material is wasted during conventional magnet manufacturing, ORNL says additive manufacturing would allow most of the material to be captured and reused.

The team fabricated isotropic, near-net-shape, neodymium-iron-boron magnets using ORNL’s Big Area Additive Manufacturing machine. Magnets produced by the process had the same or better magnetic, mechanical and microstructural properties than bonded magnets made using traditional injection molding with the same composition, according to the researchers. The results were published in the journal Scientific Reports.

The 3D printing process used composite pellets consisting of 65% isotropic NdFeB powder and 35% polyamide (Nylon-12) manufactured by Magnet Applications Inc. The pellets were melted, compounded and extruded layer-by-layer into intended forms.

The researchers now plan to evaluate the printing of directional, bonded magnets, which are stronger than isotropic magnets that have no preferred magnetization direction. The team, which is led by Alex King, the director of ORNL’s Critical Materials Institute, also will examine the effect of binder type, the loading fraction of magnetic powder, and processing temperature on the magnetic and mechanical properties of printed magnets.