Modeling in-situ magnetic alignment during magnetic 3D printing

Abstract

Additive manufacturing (AM) via 3D printing technologies have become a frontier in materials research, including its application in the development and recycling of permanent magnets1,2. The limited availability of the rare earth elements (REEs) for magnets present a demanding challenge and necessitates reduction in the losses of REEs from conventional or subtractive manufacturing. AM allows for a minimal waste production and re-utilization of recovered rare earths in the magnet processing. In-situ alignment during 3D printing of magnetic materials has opened new horizons for manufacturing of complex permanent magnets3,4. The introduction of functionalized magnetic 3D printing as an AM process allows rapid prototyping of multi-directionally aligned magnetic systems, and reduced energy requirement due to the elimination of post-production alignment3.In this work, we have developed a robust multiphysics model to simulate the alignment of magnetic particles in a polymer matrix, during 3D printing. Magnetization vs. field measurements of extruded and printed Sm-Co bonded in PLA (15 vol.%) and Nd-Fe-B+Sm-Fe-N bonded in Nylon 12 (65 vol.%), with and without alignment, confirmed the alignment of magnetic particles. A parametric analysis was performed to understand the effect of process variables, like alignment field, loading fraction, printing speed and particle size, on the degree of alignment of the samples (Fig.1)5. The model is upgraded to consider variable particle size distributions, non-homogenous particle spacing and different printing temperature. The model predicts a competing behavior between particle-fluid and particle-particle interactions under magnetic field. The model provides a framework to efficiently predict the DoA in tandem with a functionalized-magnetic 3D printer and allows the user to adjust the operating parameters according to the desired DoA.This work is supported by the Critical Materials Institute (CMI), an Energy Innovation Hub funded by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. Ames Laboratory is operated for the U.S. DOE by Iowa State University of Science and Technology under Contract No. DE-AC02-07CH11358.