A Brief Understanding of Neodymium Iron Boron Magnets

Update:17 Aug 2020

Strong NdFeB Magnet boron magnets are the third generation of rare earth permanent magnets, which are mainly composed of rare earth metal neodymium, metallic element iron and non-metallic element boron, and other elements in appropriate proportions are added as needed. A magnetic material made after crushing, pressing, sintering and aging. Neodymium magnets have high remanence, high coercivity, high energy product, high performance and high cost performance, and are currently the strongest magnets in the world.

  1. Production process

Neodymium, iron, boron and some transition metals are smelted, crushed, and powdered to become alloy powders, and then the alloy powders are placed in a mold to form, and sintered to fix the shape. There are two ways of forming, mould pressing and isostatic pressing. The sintered blank requires finishing processing to reach the final tolerance.

  1. Processing tolerance

Generally speaking, neodymium magnets must be processed by a diamond grinding wheel. Sometimes, molybdenum wire is also used for wire cutting, but the surface finish obtained by wire cutting may not be satisfactory. Generally, the standard tolerance of NdFeB magnet processing is ±0.1mm.

  1. Surface treatment

The corrosion resistance of neodymium iron boron magnets is very poor, so the surface needs to be treated. The conventional coatings of NdFeB are: nickel, zinc, nickel copper nickel, gold, silver, tin, chromium. In addition, special surface coatings are required, such as ABS coating, rubber coating, PTFE coating, stainless steel housing and epoxy coating.

  1. Magnetization and packaging

The magnetization of neodymium iron boron magnets requires a very strong magnetic field, which is magnetized along the direction of magnetization. Under certain conditions, a customized magnetizing fixture can be used for multi-stage magnetization of the product. NdFeB magnets are anisotropic and can only be magnetized along the magnetization direction. Therefore, when designing complex components, the magnetic properties of the product after installation must be considered.

NdFeB magnets are very magnetic in custom industrial magnets, but their machining performance is weak, so they should be packaged properly and handled carefully to ensure the safety of the product and the operator.