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How to judge the quality of the sintered ndfeb magnet?

by:Newland     2020-05-03
Sintered ndfeb magnet, for promoting the advancement of modern technology and society is one of the important material, widely used in the following areas: computer hard drives, magnetic resonance imaging permanent magnet motor, electric cars, wind power generation, industry, consumer electronics, CD, DVD, mobile phones, audio, duplicator, scanners, cameras, camera, fridge, TV, air conditioning, etc. ) And the magnetic force, magnetic levitation, magnetic transmission machinery, such as the industry. Since 1985 in Japan, China and Europe and the United States began to industrialization at the same time, the nearly 30 years industry booming global permanent magnet materials, the magnetic can keep a record, increasing material varieties and grades. With expansion of the market, its manufacturer also is increasing, and a lot of customers are hard to avoid in such confusion, how to judge the merits of the product? The most comprehensive judgment method: first, the magnet performance; Second, the size of the magnet; Three, magnets plating. First of all, the magnet performance guarantee from raw material to produce process control 1, according to the enterprise manufacturing high-grade or middle-grade or low-grade sintered ndfeb requirements, according to the regulations of the national standard of raw material composition to the choose and buy raw materials. 2, the production technology of advanced or not directly determine the performance of the magnet quality. 3, magnetic field orientation, our country is the only country adopts two-step forming technology in the world, orientation with a small vertical moulding pressure, finally USES the isostatic pressing molding, this is one of the most important characteristics of sintered ndfeb industry in our country. 4, and the quality of the production process monitoring is very important, can by SC chip thickness measurement and detection way JM powder particle size distribution, etc. The high quality product is depends on the production process control, but the customer will be confused, how to determine the performance of the product I bought? The China institute of metrology has developed a variety of models of the permanent magnet magnetic materials technology parameter measuring instrument. Magnetometer (pulse magnetic field 烤瓷) Is a kind of test instruments, high coercive force of permanent magnet is mainly in order to adapt to electric cars and large demand high coercive force of permanent magnet by permanent magnet motor. Second, the security of the magnet size depends on the factory processing power of the actual application of sintered ndfeb magnet shape is varied, such as wafer, cylinder, cylinder ( There are inner hole) ; Square, square, square column; Clay shape, fan, trapezoidal, polygon and all kinds of irregular shape, etc. Every kind of permanent magnets in the shape of a different size, it's hard to do a molding production process. General production process is: Mr Output large ( Big size) Billet, after sintering and tempering treatment, and then through the mechanical processing ( Including cutting, punching) And grinding, surface coating ( Coating) Processing, and then to a magnet properties, surface quality and dimension precision of detection, and then the magnetization, packaging and delivery. Again, the magnet coating quality directly determine the product application life, 1 cm3 of sintered ndfeb magnets stay 51 days in 150 ℃ in air, will all be oxidation corrosion. It is more easy to corrode in weak acid solution. In order to make the ndfeb permanent magnets durability, asked 20 - it is The service life of 30 years, its must undergo surface anti-corrosion treatment, in order to resist corrosive medium corrosion of magnet. At present, sintered ndfeb magnets industry widely used metal plating, plating + chemical metallized, electrophoresis coating and phosphating treatment methods, such as additional spacer on the magnet surface plating layer, isolated from the surface of magnets and the corrosive medium, in order to prevent the medium for violation of the magnet. In conclusion, the customer only by understanding the production process, understand the requirements of the product, to correct the judgment of the eligibility of the product. Simple summary, is the understanding of performance and dimensional tolerance control, coating testing and assessment of the appearance. Performance test performance, can pass the Br ( Remanence) 、Hcb( Coercive force) 、Hcj( Intrinsic coercive force) 、( BH) max( The maximum magnetic energy product) As well as the demagnetization curve; Size tolerance, can using vernier caliper to measure the precision; Coating, can be observed by naked eye coating color brightness and through binding force, salt spray testing and other testing methods; The overall appearance, mainly with the naked eye or a magnifying glass, or optical microscope ( For which affects less than 0. 2 mm below the product) Smooth surface, sintered ndfeb magnet, no visible particles and foreign body, no spots, no edge Angle, appearance is qualified.
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