There are several production processes for permanent magnets, do you understand them?
1) Sintering process
Sintering process is a powder metallurgy method, which is the most widely used production process at present, applicable to the production of sintered NdFeB, permanent magnet ferrite, samarium cobalt and sintered alnico magnets.
Casting is a process in which solid metal is dissolved into a liquid state and poured into a specific shape to be solidified and formed. For permanent magnets, the casting process is mainly used to produce cast alnico magnets. Compared with sintered Alnico, cast Alnico has higher magnetic properties and can be processed into different sizes and shapes, while sintered Alnico has a simple process, small tolerances on blank dimensions and good processability.
3) Bonding process
Bonding process is a kind of production process in which powdered permanent magnets with certain magnetic properties are mixed uniformly with adhesive and other additives in a certain proportion, and then pressed, extruded and injection molded to produce composite permanent magnets. Compared with sintered and casted permanent magnets, the outstanding advantages of bonded permanent magnets are: high dimensional precision, no deformation, no secondary processing; large degree of freedom of form, according to the actual use, resulting in various shapes of products, such as long strips, sheets, tubes, rings or other complex shapes; easy to mass automated production; and high mechanical strength of the product. The disadvantages are low magnetic properties and low use temperature. The key technologies in the bonding process are: the preparation of magnetic powder, the choice of coupling agent and adhesive, the amount of binder added, the pressure of molding and orientation magnetic field strength. The main manufacturing methods of magnetic powder used for bonding NdFeB are melt quick quenching method, HDDR method, mechanical alloying method and gas spray method. Among them, the HDDR method is more popular at present.
( 4) hot pressing and deformation process
The hot pressing and deformation process is another process for producing NdFeB magnets. By this process, isotropic and anisotropic NdFeB magnets can be produced. The NdFeB magnets produced by this process have high magnetic properties, the maximum radial magnetic energy product can reach 240~360 kJ/m3, high heat resistance, the operating temperature can reach 180 ℃, the magnetic ring is nanocrystalline structure, high density, epoxy resin electrophoresis coating, excellent corrosion resistance. The thermo-anisotropic radiation oriented ring magnets are mainly used in EPS motors, servo motors, power tool motors, and all kinds of DC motors.