Multipole ring magnets are a more desirable solution to the permanent magnet motors and magnetic coupling devices in comparison with conventional splicing several arc magnets. It can be classified to isotropic type and anisotropic type. Isotropic type is generally refers to ring-shaped bonded magnets with multipole. Anisotropic type, or multipole sintered ring magnet, has always been touted as a high-end product.
About Multipole Sintered Ring Magnet
Take sintered Neodymium magnets as an example, either radial orientation or multipole orientation can be served to produce multipole sintered ring magnet. Radially oriented ring magnets made by radial orientation can be directly magnetized to multipole along the radial vector. The mainstream generation mode of radial orientation magnetic field includes traditional repulse orientation technology and Chinese unique rotating orientation technology.
Multipole sintered ring magnet manufactured by multipole orientation are also known as polar anisotropic magnets. Orientation magnetic field of polar anisotropic magnets is generated by pulser coil. Its flux lines enter adjacent S polars from N polars and exhibit a curve distribution, thereby magnetic powder also present curve arrangement. Magnetic field strength waveform of polar anisotropic magnets is close to sinusoidal and very advantageous to the motor applications.
Besides sintering technology, hot-deformation process is another solution to obtain multipole Neodymium ring magnet as well.
Waveform vs. Motor Performance
Comparative measurement method of multipole ring magnet is mainly characterized via magnetic field strength waveform, its parameters like peak value, angle, and cycle duty is closely related to the motor performance. Peak values can indicate grade of magnet and saturation degree of magnetization. Peak value deviation and angle deviation have significantly influenced on motor efficiency, cogging torque, temperature increase, and noise. Both two parameters can be modified thorough optimization of production technology and magnetizing fixture. In addition, area and duty cycle will impact electromotive force (BEMP), rated torque, and power.
