Because magnets fabricated using Nd-Fe-B exhibit excellent magnetic properties, this novel material is used in various high-tech industries. However, because of the brittleness and low formability of Nd-Fe-B magnets, the design freedom of shapes for improving the performance is limited based on conventional tooling and postprocessing. Laserpowder bed fusion (L-PBF), the most famous additive manufacturing (AM) technique, has recently emerged as a novel process for producing geometrically complex shapes of Nd-Fe-B parts owing to its high precision and good spatial resolution. However, because of the repeated thermal shock applied to the materials during L-PBF, it is difficult to fabricate a dense Nd-Fe-B magnet. In this study, a high-density (>96%) Nd-Fe-B magnet is successfully fabricated by minimizing the thermal residual stress caused by substrate heating during L-PBF.

In this research, the magnetic abrasive finishing process using (Nd-Fe-B) permanent magnet was applied to confirm the performance and to find the optimum conditions. The STS304 bar was used as the specimen in this experiment. In order to confirm the performance of magnetic abrasive finishing process, the surface roughness (Ra) and diameter reduction were measured when the specimens were processed under the conditions of rotational speeds, frequencies, and magnetic pole shapes. The rotational speeds were varied at 8000rpm, 15000rpm, 20000rpm, and 25000rpm. And the frequencies were changed to 0Hz, 4Hz and 10Hz. Also the shapes of the magnetic pole were changed to flat edge, sharp edge and round edge. It can be concluded that the surface roughness (Ra) and diameter reduction were found to be the best at 25000rpm, 4Hz, flat edge.

This paper studies the repulsion occurring between the permanent magnet by the simulation analysis. Nowadays, there are many cases such as magnetic levitation, safety bumper device and so on using the properties of the permanent magnet. As the neodymium magnet of the powerful ferromagnetic material is less expensive by comparing with the strong magnetic force for industrial, medical areas and etc., it can be used at the various applications. The prediction of the magnetic force is becoming increasingly important in order to be used effectively permanent magnet in various fields. Therefore, the results of the magnetostatics by Ansys and the MAXWELL of commercial electromagnetic analysis software are analyzed and compared. Magnetic force is inversely proportional to the distance and power. In this paper, the permanent magnet was simulated and compared by the two permanent magnets of the small sizes with the diameter of 4mm and the length of 8mm. In addition, the forces between the ferromagnetic iron and permanent magnets are simulated.

Magnetic properties and the microstructures of magnets prepared by spark plasma sintering were investigated in order to enhance magnetic properties by grain size control. Nd-Fe-B magnets were fabricated by the spark plasma sintering under 30 MPa at various temperatures. The grain size was effectively controlled by the spark plasma sintering and it was possible to make Nd-Fe-B magnets with grain size of 5.9 .

환원.확산법에 의해 Sm2Fe17Nx 계 희토류 영구자석을 제조하기 위한 기초연구로서, 우선 Sm2Fe17 금속간화합물의 제조를 위하여, 금속 Ca에 의한 Sm2O3의 환원반응과 Fe분말중에 Sm의 확산반응을 검토하였다. 그 결과 전자는 1000˚C이상의 고온의 경우에 매우 빠르게 완료되지만, 후자의 Fe분말의 중심까지 Sm의 확산반응의 완료(완전한 균질화조건)는 1100˚C에서 3h 정도의 R-D 반응이 필요하며, 이 확산반응이 전체반응에 있어서 율속단계임을 알았다. Sm-Fe 계의 금속간화합물들의 성장은 1000˚C이하에서는 SmFe2, SmFe3,Sm2Fe17금속간화합물의 3개의 상이 관찰되었으나, 1100˚C에서는 Sm2Fe17 금속간화합물의 상만이 관찰되었다. 본 연구에서 얻어진 최종시료의 산소 및 Ca량은 각각 0.72wt% 및 0.11wt%이었다.