Fabrication of highly dense isotropic Nd-Fe-B nylon bonded magnets via extrusion-based additive manufacturing

Ling Li, Oak Ridge National Laboratory
Kodey Jones, Oak Ridge National Laboratory
Brian Sales, Oak Ridge National Laboratory
Jason L. Pries, Oak Ridge National Laboratory
I. C. Nlebedim, Ames Laboratory
Ke Jin, Oak Ridge National Laboratory
Hongbin Bei, Oak Ridge National Laboratory
Brian K. Post, Oak Ridge National Laboratory
Michael S. Kesler, Oak Ridge National Laboratory
Orlando Rios, Oak Ridge National Laboratory
Vlastimil Kunc, Oak Ridge National Laboratory
Magnet Applications, Inc.
Magnet Applications, Inc.
Arnold Magnetics Technologies
Thomas A. Lograsso, Iowa State University and Ames Laboratory
M. Parans Paranthaman, Oak Ridge National Laboratory

This is a manuscript of the article published as Li, Ling, I. C. Nlebedim, Thomas A. Lograsso, et al. "Fabrication of highly dense isotropic Nd-Fe-B bonded magnets via extrusion-based additive manufacturing." Additive Manufacturing 21 (2018): 495-500. DOI: 10.1016/j.addma.2018.04.001. Posted with permission.


Magnetically isotropic bonded magnets with a high loading fraction of 70 vol.% Nd-Fe-B are fabricated via an extrusion-based additive manufacturing, or 3D printing system that enables rapid production of large parts. The density of the printed magnet is ∼ 5.2 g/cm3. The room temperature magnetic properties are: intrinsic coercivity Hci = 8.9 kOe (708.2 kA/m), remanence Br = 5.8 kG (0.58 T), and energy product (BH)max = 7.3 MGOe (58.1 kJ/m3). The as-printed magnets are then coated with two types of polymers, both of which improve the thermal stability as revealed by flux aging loss measurements. Tensile tests performed at 25 °C and 100 °C show that the ultimate tensile stress (UTS) increases with increasing loading fraction of the magnet powder, and decreases with increasing temperature. AC magnetic susceptibility and resistivity measurements show that the 3D printed Nd-Fe-B bonded magnets exhibit extremely low eddy current loss and high resistivity. Finally, we demonstrate the performance of the 3D printed magnets in a DC motor configuration via back electromotive force measurements.