How to distinguish between sintered neodymium magnets and bonded neodymium magnets?

Neodymium Magnets are the strongest permanent magnets in the magnet family. It`s grade ranges from N35 to N52, and shape can be customized into round, block, countersunk, arc, cylinder, triangular and so on through various machining process.

How do we distinguish between bonded and Sintered Neodymium Magnets? In fact, as both types are made from neodymium magnets, the major difference between bonded and sintered is from the production process. Bonded magnets are manufactured through molding while sintered magnets are produced through vacuuming and high-temperature sintering. Bonded magnets contain binding agents since it is molded and pressed into shape, so its density is only 80% of what it could be in theory. On the other hand, sintered magnets are produced through a more complex process under high temperature, so its magnetic strength is 30% higher than that of bonded magnets. Sintered neodymium magnets are strong permanent magnets produced by sintering raw material powder. Machining process (multi-wire cutting, drilling, grinding) are necessary for the sintered raw material piece to produce the various shape of magnets required. Since the process of manufacturing sintered neodymium magnets is difficult due to complex machining, the operational cost is higher, precision regarding size is off by a little and surface treatment is usually needed for anti-corrosion purpose. However, it is still the preferred option for many applications due to its high performance in terms of magnetic force compared to Bonded Neodymium Magnets.