3D printed NdFeB permanent magnets by laser powder bed fusion: process feasibility, optimization and annealing

Purpose This study aims to assess the feasibility of laser powder bed fusion (LPBF) processing using as-received gas-atomized spherical Neodymium-Iron-Boron (NdFeB) powder (17–68 µm), compared to literature methods that sieve to a narrow size range (<40 µm). Design/methodology/approach The research involves single track and layer printing, process optimization and subsequent heat treatment and magnetic annealing. The experimental approach includes conducting systematic printing trials to assess the impact of various parameters on printed track and layer quality, and refining printing parameters through iterative testing. Heat treatment and magnetic annealing are applied to achieve the desired magnetic properties. Findings A minimum linear energy density of 0.10 J/mm is required for continuous track formation, with track width largely unaffected by varying linear energy densities. An optimal hatch spacing of approximately 42% overlap avoids layer defects, with 0.10 mm spacing suitable for layer thicknesses between 30 and 80 µm. A stable processing window for energy density (EA) of 0.6–1.0 J/mm2 was identified, allowing cuboid printing despite some discontinuous tracks, indicating potential fusion issues. Maximizing volumetric energy density (EV) within this range correlates positively with part density, achieving 92% density, coercivity of 490 kA/m and remanence of 496 mT. Post-treatment, density increased to 96%, coercivity to 582 kA/m and remanence to 544 mT. Originality/value This study fills a significant gap in LPBF literature for NdFeB by using the original wider size range of spherical powder without sieving, demonstrating improved cost-effectiveness, material efficiency and build efficiency. These findings offer practical recommendations for addressing the challenges related to LPBF processing of NdFeB powder.