NdFeB magnet knowledge-dimensional accuracy, production and processing technology and production materials

Dimensional accuracy of NdFeB products

The dimensional accuracy of NdFeB products, which is more economical, is around (+/-)0.05mm. In fact, the existing processing methods can reach an accuracy of (+/-)0.01. However, since neodymium iron boron generally needs to be electroplated, it needs to be cleaned before electroplating. The corrosion resistance of this material is very poor, and the dimensional accuracy will be washed away during the pickling process. Therefore, the accuracy of a truly electroplated product cannot reach the level of simple cutting and grinding.

The processing technology of NdFeB:

There are basically two types: slicer cutting or wire cutting.

The slicing machine is a diamond inner hole cutting blade with a thickness of about 0.3mm, which cuts the magnet to the required size as required. But this method is only suitable for simple square shapes and cylindrical shapes. Due to the inner hole cutting, the size of the magnet cannot be too large, otherwise it cannot be placed inside the blade.

Another method is wire cutting. Generally used to cut tiles and large-size products.

Punching: Small holes are usually drilled with a vibrating diamond wheel drill bit. For large holes, the method of sleeve holes is adopted, which can save material costs.

The main raw material for the production of NdFeB magnets

The main raw materials for the production of NdFeB magnets are rare earth metal neodymium, rare earth metal praseodymium, pure iron, aluminum, boron iron alloy and other rare earth materials.

Normally, neodymium magnets are mainly punched with countersinks, but also with straight holes. For example, the processing method of countersunk ring magnet is to dig holes or drill holes again after slicing, and the processing technology requirements are more exquisite. If a strong magnet already has magnetic force, it needs to be demagnetized 1st, then drilled, and then re-magnetized after the finished appearance specifications are manufactured. Generally, the magnets are made into cylinders or square cylinders.

Neodymium iron boron magnets can be widely used in motors, engines, voice coil motors, magnetic resonance imagers, communications, control instruments, audio equipment, etc.

A fully automatic luxury car consumes about 0.5kg～3.5kg of rare earth permanent magnet materials; there are more applications of neodymium magnet materials in new energy vehicles, and each hybrid car consumes about 5kg more neodymium-iron-boron than traditional cars. Pure electric vehicles use rare earth permanent magnet motors to replace traditional generators, and use 5-10kg neodymium iron boron. With the development of the automobile industry and the continuous improvement of electronic technology requirements, the demand for NdFeB permanent magnet materials will increase.

The automotive industry is one of the fastest growing areas of NdFeB permanent magnet applications. In each car, there are generally dozens of parts such as engines, brakes, sensors, meters, speakers, etc., which will use 40 to 100 NdFeB series and SmFeN series sintered magnets.

The voice coil motors supporting computer hard drives account for 40% to 50%, so the computer industry is currently the largest user of permanent magnet motors.