Micro-motor rotor magnets formed integrally with the shaft

In the field of micro motors, rotor magnets formed integrally with the shaft are increasingly becoming a widely adopted structural solution. Compared to the traditional “magnet + shaft post-assembly” approach, this type of rotor offers significant advantages in structure, performance, and consistency. It is particularly well-suited for micro motor applications demanding high precision, reliability, and compact size.

Structurally, one-piece shaft-integrated micromotor rotors typically employ composite magnetic materials, such as injection-molded magnets (mostly injection-molded ferrites). The shaft and magnet are simultaneously formed within the mold, with the magnet directly encapsulating the metal shaft to create a highly coaxial monolithic structure.

Rotor magnet integrated with steel shaft via injection molding

Regarding magnetic performance and consistency, monolithic rotors are highly suitable for multi-pole radial magnetization configurations, such as 4-pole, 6-pole, 8-pole, or even higher pole counts. Moreover, the monolithic molding process achieves superior concentricity and dimensional consistency, minimizing assembly errors. This is critical for micro motors, as even minor eccentricity can cause vibration, noise, and efficiency loss.

Regarding mechanical properties and reliability, injection-molded magnets (plastic + magnetic powder) inherently possess greater toughness. When molded as a single unit with the shaft, these rotors offer superior resistance to vibration and impact. Compared to sintered neodymium-iron-boron magnets, which are prone to brittleness and chipping, injection-molded magnets better withstand mechanical stress impacts. When the motor experiences sudden load changes, drops, or external vibrations, the integrally molded rotor absorbs part of the stress through the material's inherent toughness. This reduces the likelihood of magnet cracking or fragmentation, enhancing overall system reliability at the structural level.

This concludes the introduction to micro-motor rotor magnets formed integrally with the shaft. They are suitable for micro-motor applications demanding high durability and operating in relatively complex environments.