The advantages of radially magnetized ring in motors

what is radially magnetized ring magnet?

Radial ring magnet, the magnetic pole direction is radial from the center to the surrounding. Its magnetic pole position and number of magnetic pole pairs depend on the magnetizing method. There are also many magnetizing methods. According to the magnetizing method, it can be divided into unipolar magnets, multi-stage magnets, direct impulse magnets, and oblique magnets. The number of magnetizing poles and the angle of oblique charging are determined by the final magnetizing fixture.

Radial ring magnets include sintered rare earth magnets, sintered ferrite magnets, hot-pressed/thermally deformed magnets and bonded magnets. The radial magnets that people generally use and talk about are basically sintered rare earth magnets, and radial ring sintered magnets can be divided into NdFeB and SmCo according to the material. Sintered neodymium iron boron magnets are usually used for the rotor of the motor.

The biggest role of radial orientation technology is to help anisotropic magnets achieve multi-pole magnetization and expand their applications in various fields. Mainly used in the motor industry, mostly is multi-pole magnetization.

Application of radial magnets in motors

The rotor of a brushless DC motor is composed of permanent magnets with a certain number of pole pairs embedded on the surface of the iron core or embedded in the iron core. Permanent magnets are mostly made of rare earth permanent magnet materials with high coercivity and high permeability induction density such as neodymium iron boron. The role of the permanent magnet of the rotor is similar to that of the permanent magnet used in the brushed motor. They both establish a sufficient magnetic field in the air gap of the motor. The difference is that the permanent magnet in the brushless DC motor is installed in the rotor. Above, the magnet of the brushed motor is mounted on the stator.

The rotor structure of the brushless DC motor mostly adopts surface-bonded magnetic poles, also called tile-shaped magnetic poles. The surface-adhesive magnetic pole is to paste a radially magnetized tile rare earth permanent magnet on the outer surface of the iron core. A reasonable design can obtain the air gap magnetic flux density in the form of a square wave. In order to reduce cogging torque when used in a motor, a rotor in which a ring magnet is divided into segmented magnets and the cross-sectional shape of the magnet is formed into a semi-cylindrical shape has been proposed. In addition, each magnet is attached using an adhesive between the protrusions.

Superior performance of radial magnet

The use of multi-stage neodymium iron boron magnets replaces the cumbersome and time-consuming method of attaching block or arc magnets to the motor rotor shaft in pieces.

These sintered radial ring magnets are widely used in servo motors, synchronous motors, electromagnetic bearings, electromagnetic clutches, actuators, etc.

Multi-pole radial ring magnet, only one piece can be easier to install and install the motor.

At present, magnets with multi-pole magnetization on the outer or inner diameter are often used in servo motors, couplings, and spindle motors.

Magnets with opposite outer and inner diameters are often used in linear actuators, high-end speakers, magnetic bearings and compressors.

Advantages of radial magnets

• The assembly process of the motor assembly is much easier than gluing the arc-shaped magnet on the ring, and the assembly cost is much easier.

• Improve the uniformity of the magnetic flux, thereby increasing the efficiency of the motor. The assembly accuracy of the radial ring magnet will be much higher than that of the traditional multi-arc assembly, thus improving the dynamic balance of the motor.

• Improve raw material utilization.

• Modify the distribution of the surface magnetic field, the motor powder will increase by more than 15%.