title: [Sandwich type dental magnetic devices of Nd-Fe-B magnet and permendur].
abstract: Nd-Fe-B magnets have a very high maximum energy product (BH max), which is defined as the attractive strength between a magnet and opposing magnetic materials. Permendur (Fe-49 Co-2 V) has the greatest magnetic saturation (Bs), which makes it strongly magnetized. If magnetic retainers were made with Nd-Fe-B magnets and a permendur yoke, they would be small and have strong retention. The purpose of this investigation was to develop small dental magnetic devices with Nd-Fe-B magnets and permendur yokes. The magnetic devices form sandwich-type magnetic circuits with magnetic stainless steel keepers. A 4 x 3 x 2 mm rectangular prism Nd-Fe-B magnet was used. The magnet was sandwitched between the semi-columnar yokes. To protect the magnet from corrosion, the devices were encapsulated with 304 stainless steel by silver brazing and adhesion bonding of a stainless steel tube and foil. The optimum cross-sectional area of the yoke was determined experimentally. The dimensions of the devices were phi 5 x 3.5 mm for 4 x 3 x 2 magnet. The breakaway retention for a keeper of magnetic stainless steel (Type XM 27) was 852 g on average. This breakaway retention is sufficient for dental prosthetic applications.
authors.forename: O
authors.initials: O
authors.lastname: Okuno
authors.forename: T
authors.initials: T
authors.lastname: Nakano
authors.forename: H
authors.initials: H
authors.lastname: Hamanaka
authors.forename: Y
authors.initials: Y
authors.lastname: Kinouchi
mesh_terms: D001608:Beryllium; D003722:Dental Alloys; D003781:Denture Retention; D007501:Iron; D008280:Magnetics; D009354:Neodymium
chemical_list: D003722:Dental Alloys; D009354:Neodymium; D007501:Iron; D001608:Beryllium