How to distinguish between bonded NdFeB and sintered NdFeB?
Neodymium magnets, which can be called neodymium iron boron magnets, are collectively referred to as powerful magnets. Their chemical formula is Nd2Fe14B, which is an artificial permanent magnet. It is a permanent magnet with the strongest magnetic force to date. NdFeB magnets have N35-N52 material grades; the shape can be processed into different shapes according to specific requirements, such as circular, square, hole, magnetic tile, magnet bar, convex or trapezoidal.
How to distinguish between bonded NdFeB and sintered NdFeB? In fact, both of these magnets are NdFeB. The distinction between these two magnets is based on their different production processes. The bonded NdFeB is actually formed by injection molding, and the sintered NdFeB magnet is molded by evacuating and then heating at a high temperature.
Bonded NdFeB magnets, because they are injection molded, contain adhesives, which typically have a theoretical density of 80%. The sintered neodymium-iron-boron magnets are heated by a complex process at a high temperature, so the magnetic properties of bonded neodymium-iron-boron are reduced by about 30 percent relative to sintered neodymium-iron boron.
Sintered NdFeB is an anisotropic magnet produced by powder sintering. Generally, only blanks can be produced after sintering, and then mechanical processing (such as wire cutting, slicing, grinding, etc.) can become magnets of various shapes. Sintered NdFeB is a brittle and hard material that is difficult to process. It has large loss during processing, high cost, poor dimensional accuracy, and poor corrosion resistance. The surface needs electroplating. However, the advantage is that the performance is higher. At present, more than 50M has been achieved.
Taken together, the magnetic properties of bonded NdFeB magnets are only about 5% of that of sintering. At present, the magnetic energy product of sintered NdFeB magnets can reach more than 50M, while the bonded magnets are generally below 10M, and the best is only 12M. The magnetic powder used for bonded magnets generally has a performance of 15 M and a maximum of 10.5 M after being made into a bonded magnet. Sintered NdFeB is therefore generally used in a wider range than bonded NdFeB.