China Neodymium And Ferrite Magnets Manufacturer & Supplier 
In modern motor applications, brushless external rotor motors are widely used in fans, drones, electric skateboards, fitness equipment, and other fields due to their compact structure, smooth operation, and low noise. In the “power heart” of such motors, magnetic rings play a crucial role as key magnetic components. The following is an introduction to the basic knowledge of magnetic rings.
A brushless external rotor motor is a special type of motor with a unique structure where the rotor is positioned externally and the stator internally. Unlike traditional internal rotor motors, the rotor of an external rotor motor is an integral part of the motor housing, driving the motor by rotating the entire housing. The magnetic rings are either adhered to or embedded in the inner wall of the rotor housing, serving as the core components that provide permanent magnet excitation. The magnetic field of the magnetic rings interacts electromagnetically with the stator windings, thereby driving the motor to rotate, forming the foundation for the motor to generate torque.
The inner hole of the magnetic ring of an external (outer) rotor motor is usually relatively large.
There are four main types of magnetic ring materials for brushless external rotor motors, each designed to meet different application requirements.
Bonded and injection-molded neodymium magnetic rings:These are formed using injection molding or bonded compression molding processes, enabling them to be molded into a complete ring shape and even achieve multi-pole magnetization in a single step. Their high magnetic performance makes them widely used in medium-to-low-speed devices such as fans and smart home appliances. Their magnetic performance is slightly lower than that of sintered magnets, but they offer significant advantages in terms of lightweight and compact design.
Sintered and injection-molded ferrite magnetic rings:Although their magnetic performance is lower, they offer advantages such as corrosion resistance and stability, and are commonly used in mid-to-low-end fans or industrial blowers.
Additionally, there are also magnetic ring assemblies made from magnetic tiles (arc shape), which require high assembly precision.
Magnetic ring polarity and magnetization method;
The magnetic poles of the magnetic ring are usually arranged radially, i.e., the N pole and S pole are arranged alternately along the circumference. According to the motor design requirements, the magnetic ring can be made into 4 poles, 6 poles, 8 poles, 10 poles, 12 poles, 14 poles, or even more poles. The more poles there are, the smoother the motor runs, but the speed is relatively reduced.
If you need to customize various types of multi-pole neodymium or multi-pole ferrite magnetic rings, please feel free to contact us. We can also provide samples of similar sizes for testing.
Some samples;
R28 x r25 x L15 x W17 mm outer rotor motor curved ferrite