Due to the Advancement of science and technology, contemporary society has derived many high-tech products, such as computer hard drives, electric vehicles, and magnetic levitation technologies. Nowadays, sintered neodymium ferroboron magnets are widely used in these high-tech industries. The quality of that product, Good or bad is very important to this product
How to judge the quality of the product?
The most comprehensive method of judgment: First, magnet coating; Second, magnet performance; Third, magnet size.
The guarantee of magnet performance comes from the control of raw material production process
1, magnetic field upward, China is the only country in the world to use two-step press molding, the orientation of vertical molding with small pressure, and finally the use of quasi-isostatic pressure molding, which is the sintering neodymium iron boron industry in China is one of the most important features.
2, and, the quality of the production process is very important, can be controlled by SC film thickness measurement and JM particle size distribution and other detection methods. The quality of the product depends on the control of the production process, but the customer will be very confused, how to judge the performance of the product I purchase? The China Institute of Metrology has developed various types of magnetic parameter measurement instruments for permanent magnetic materials. Pulsed magnetic field magnetometer(PFM) is a test instrument for testing ultra-high recalcitrant permanent magnets. It is mainly designed to meet the high recalcitrant permanent magnets required in the field of electric vehicles and large permanent magnetic Motors.
3, according to the requirements of enterprises to manufacture high-end or mid-grade or low-grade sintered neodymium iron boron, raw materials are purchased according to the raw material components stipulated by the National standards.
4, the advanced production process directly determines the performance of the magnet quality. The most advanced technologies at present are scale ingot(SC) technology, hydrogen fragmentation(HD) technology and air flow grinding(JM) technology. Small capacity vacuum induction smelters(10kg, 25kg, 50kg) have been replaced by large capacity(100kg, 200kg, 600kg, 800kg) vacuum induction furnaces. SC(Stipcasting) die-casting technology has gradually replaced large ingots(ingots with a thickness greater than 20-40 mm in the cooling direction), Hydrogen fragmentation(HD) technology and gas flow grinding(JM) replaced the jaw Crusher, disc grinder, ball grinder(wet method powder) to ensure the uniformity of the powder and facilitate liquid phase sintering and grain refinement.
Customers can select their own neodymium iron and boron brands based on magnet parameters Br(magnetic), Hcb(coercive force), Hcj(internal coercive force), and(BH) Max(maximum magnetic energy product). At the same time, these four parameters are to determine whether the product is produced according to customer requirements. The guarantee of magnet size depends on the processing strength of the factory
The practical application of neodymium ferroboron is varied in shape, such as circular, cylindrical, cylindrical(with inner holes); Square, Square, Square columnar; Walled, fan-shaped, trapezoidal, polygonal, and various irregular shapes. Each type of permanent magnet has different sizes, and it is difficult to form it once in a production process. The general production process is: first produce large(large size) billets, after sintering and tempering treatment, and then through mechanical processing(including cutting, perforating) and grinding, surface coating(coating) treatment, The magnetic properties, surface quality and dimensional precision are then tested, and then charged, packaged and manufactured.
The surface of sintered neodymium iron boron permanent magnet element generally requires smooth and to a certain degree of accuracy. The surface of the rough delivered magnet needs surface grinding. The commonly used grinding methods for diamond neodymium ferroboron permanent magnetic alloys include plane grinding, double-end grinding, inner round grinding, and outer round grinding. Cylinders are often used without core grinding, double-ended grinding and so on. Watt-type, fan-shaped and VCM magnets use multi-position grinders.
A qualified magnet not only needs to meet the performance standards, but also the control of size tolerance directly affects its application. The guarantee of size depends directly on the processing strength of the factory, and the processing equipment is constantly updated with the economic and market needs. The trend of more efficient equipment and industrial automation is not only to meet the increasing demand of customers for product accuracy. At the same time, it also saves manpower and costs, making it more competitive in the market.
2. Processing is divided into three categories:
(1) Cutting processing: cutting cylindrical and square columnar magnets into circular slices and square slices;
(2) Shape processing: the processing of round and square magnets into sectors, tiles, or magnets with grooves or other complex shapes;
(3) Punching processing: Processing round rods and square rods into cylindrical or square cylindrical magnets. Its processing methods are: grinding slicing, electric spark cutting and laser processing.