What is hot-pressed NdFeB?

What is hot-pressed NdFeB?

The hot-pressed NdFeB permanent magnet material is prepared by hot-pressing or thermal rheological process. First, according to a certain component ratio, the NdFeB fast-quenched belt is prepared by the solution rapid quenching method, and then it is crushed into a certain particle size powder. Then in an inert gas or vacuum environment, at a certain temperature, it is compacted and pressed into a blank. At this time, the product is an isotropic magnet blank; in an inert gas or vacuum environment, replace or change the mold, increase the temperature, and add After pressing, the isotropic magnet blank is subjected to thermal rheology to produce anisotropy, and the anisotropic magnet blank is obtained. Finally, the isotropic magnet blank or anisotropic magnet blank is machined and magnetized (magnetized) to obtain the final isotropic magnet or anisotropic hot-pressed NdFeB permanent magnet material.
Hot-pressed NdFeB can achieve magnetic properties similar to sintered NdFeB without adding heavy rare earth elements. It has the advantages of high density, high orientation, good corrosion resistance, and high coercivity, but its mechanical properties are not Good and because of the patent monopoly, the processing cost is relatively high. At present, only the three companies in the market, namely General Motors, Daido and Delta Europe, have the production technology, and only Daido can realize the mass production of hot-pressed NdFeB products. In February 2018, Yinhe Magnet built the first domestic hot-pressed NdFeB production line, with a production capacity of 300 tons/year, and mass production is expected soon.
Due to the limitation of the molding technology, the hot-pressed NdFeB can only be made into a ring shape, and the application range is limited to a certain extent. It is currently mainly used in the fields of automobile EPS motors. The hot-pressed NdFeB magnet has high magnetic performance, the magnetic ring is oriented in the radial direction, and the radial magnetic performance is uniform, which can make the motor run quietly and the torque output is smooth.
The replacement of sintering by hot pressing is mainly concentrated in the field of high-performance NdFeB with low dysprosium and high coercivity. This is the most profitable part of sintered NdFeB enterprises. Sintered NdFeB enterprises need to race against time and carry out technological upgrades. Including new processes represented by dysprosium and PLP.

Sintering, bonding, and hot pressing NdFeB have their own advantages

Sintered NdFeB

  • Advantages: extremely high magnetic performance, it is currently the largest magnetic material with the largest magnetic energy product up to 55MGOe (N54).
  • Disadvantages: In order to adapt to the high temperature working environment, some brands of sintered NdFeB will add medium and heavy rare earth dysprosium and terbium to improve the intrinsic coercivity and working temperature of the magnet, but this will lead to higher unit cost of the product; The process is complicated (first sintering into a blank and then machining), the processing loss is high, and the yield is affected.

Bonded NdFeB

  • Advantages: The product has high dimensional accuracy and flexible shape; it does not contain medium and heavy rare earths, and the unit cost is low; it is directly formed, and the loss during processing is low.
  • Disadvantages: The magnetic performance is low, the maximum magnetic energy product of the current product is about 12MGOe; the intrinsic coercivity and working temperature are low.

Hot-pressed NdFeB

  • Advantages: Under the condition of basically not using medium and heavy rare earths, it can achieve extremely high magnetic properties. The maximum magnetic energy product of the current product can reach 43MGOe; the processing loss is low.
  • Disadvantages: At present, it can only be made into a ring shape, which greatly limits the application range of hot-pressed NdFeB; due to the high technical barriers of hot-pressed NdFeB, currently only Japan Datong Electronics has achieved mass production in the world, and its monopoly makes its price high.

The three have little overlap in application at present

Hot-pressed NdFeB can only be made into a ring shape, which limits its application range. At present, it is mainly used in the field of automotive EPS motors; even considering the high-speed growth of hot-pressed NdFeB in the automotive EPS market and the impact of sintered NdFeB Compared with sintered NdFeB, the market size of hot-pressed NdFeB is extremely small, so the impact on the growth rate of demand for sintered NdFeB is relatively small.
Due to the huge difference in magnetic properties and molding, the intersection of bonding and sintering NdFeB is not large. Bonded NdFeB is mainly used in the fields of hard disk drive spindle motors and low-power micro motors. Sintered NdFeB Fe-boron is more used in fields such as high-power drive motors.
Source: China Permanent Magnet Manufacturer – www.ymagnet.com

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