UVボンド磁石の離型性(S18-3 粉末成形とその評価(3),S18 粉末成形とその評価)  [in Japanese] Mold releasability of Magnetic Powders Mixed with Ultraviolet Hardening Resin  [in Japanese]

There are limitations to the shapes and dimensions obtainable for magnetic compacts fabricated by conventional orientation forming under a magnetic field. In order to overcome these limitations, the authors have proposed a new magnetic forming process wherein the magnetic powders mixed with binder such as ultraviolet hardening resin (UV) or pyrolytic resin for powder injection molding are compacted in the molding die followed by alignment under a magnetic field. As an example of the proposed process, a UV bonded magnet was fabricated using a binder. It was observed that the UV bonded magnet was difficult to remove from the molding die because the UV resin typically bonded to the contact surface. By using aluminum (Al) as the molding material, the bonding strength between the Al sheet and the UV magnetic powder compound was measured by a uniaxial tensile test. It was found that the bonding strength increased when the mixing ratio of the magnetic powder increased. Therefore the requirements for improved magnetic properties of the bonded magnet and for increased mold releasability are contradictory to each other. It is necessary that the mold material and the mold release agent are suitable for improved magnetic characteristics of the magnetic compacts.