Comparison of properties between sintered nd-fe-b and bonded nd-fe-b

Comparison of properties between sintered nd-fe-b and bonded nd-fe-b
1、 Sintered NdFeB magnet
Sintered NdFeB magnets are made by powder metallurgy process. First, the molten alloy needs to be crushed and pressed in a magnetic field to form a compact, and then sintered in inert gas or vacuum to achieve densification.
In general, only rough magnets can be produced after sintering, and then made into magnets of various shapes through mechanical processing (such as wire cutting, slicing, grinding, etc.).
Sintered NdFeB permanent magnets are widely used in electronics, motors, medical devices, toys, packaging, hardware machinery, aerospace and other fields. The most common are permanent magnet motors, loudspeakers, magnetic separators, computer disk drives, magnetic resonance imaging equipment and instruments.
Compared with bonded NdFeB magnets, sintered NdFeB magnets have high processing cost, large loss in processing and poor dimensional accuracy. But the advantages are obvious. At present, the maximum value of sintered NdFeB magnets (BH) can reach more than 50M, while that of bonded magnets is generally below 10M.
2、 Bonded NdFeB magnet
Bonded NdFeB magnet, composed of Nd2Fe14B, is a synthetic magnet. Bonded NdFeB magnets are magnets made of rapidly quenched NdFeB magnetic particles and adhesives through "molding" or "injection molding".
Bonded NdFeB has the advantages of low cost, high dimensional accuracy, large degree of freedom of shape, good mechanical strength and light gravity. It is widely used in office automation equipment, motors, audio-visual equipment, instruments, small motors, meters and other fields. Machinery, mobile phones, optical discs, DVD-ROM drive motors, hard disk spindle motors, hard disks, other micro special DC motors and automatic instruments. Their annual growth rate reached 35%.
Compared with sintered NdFeB magnets, bonded NdFeB magnets can be formed once without secondary processing, and can be made into complex magnets of various shapes, which is incomparable to sintered magnets. With the help of bonded NdFeB magnets, the size and weight of the motor can be greatly reduced.
3、 What are the specific differences between bonded NdFeB and sintered NdFeB in production and processing technology, density, magnetism, surface treatment, price, etc?
Comparing the density of the two, the density of bonded NdFeB is about 6 g/cm3. The density of sintered NdFeB is about 7.5 g/cm3.
Compared with magnetic force, bonded NdFeB material contains less Nd, so its performance is not as high as sintered NdFeB. Thin wall magnetic rings are usually bonded with NdFeB. There are two surface treatments. Sintered NdFeB is usually galvanized or nickel plated, and bonded NdFeB is usually black epoxy resin.
Compared with the price, the price of bonded NdFeB will be relatively cheap. The bulk production of bonded NdFeB requires moulds, while sintered NdFeB does not.