Industry news

Modern brushless DC (BLDC) ceiling fans are highly favored for their high energy efficiency, low noise, and precise control of airflow. 

The implementation of these advantages largely relies on its core driving component - the rotor. Among them, injection molded 

ferrite magnetic rings play a key role as rotor magnetic poles.

What is an injection molded ferrite magnetic ring?

Ferrite material: mainly composed of permanent magnet strontium ferrite or barium ferrite powder. This endows it with 

hard/permanent magnetic properties - the ability to generate a stable magnetic field.

Injection molding: By mixing fine permanent magnet ferrite powder with special engineering plastics (such as nylon, PPS) 

and injecting them into molds of specific shapes under high temperature and pressure. Ultimately, a sturdy and precisely 

shaped annular magnet (magnetic ring) is formed.

Why is it the ideal choice for BLDC ceiling fan rotors?

1. Lightweight: Compared to traditional sintered ferrite magnets or rare earth magnets, the injection molding process combined 

with plastic matrix significantly reduces its weight. This is crucial for high-speed rotating ceiling fan blades, as it can reduce the 

moment of inertia, improve response speed, and reduce bearing burden.

2. Complex pole numbers and shapes: Injection molding technology can easily and accurately manufacture a complete circular 

structure with multiple pole pairs (alternating N and S poles). This meets the basic requirements for efficient commutation 

(electronic commutation) of BLDC motors.

3. Integration and strength: The magnetic ring itself is a seamless overall structure, with all magnetic poles (such as 8 poles, 12 poles, etc.)

 evenly distributed around its circumference. This design ensures the uniformity of the magnetic field and the mechanical strength of the 

structure, which can withstand the centrifugal force caused by high-speed rotation.

4. Low cost: Permanent ferrite powder has abundant raw materials and is much cheaper than rare earth magnets. The mature injection 

molding process is suitable for large-scale production, further reducing costs and making it highly competitive in consumer grade 

household appliances such as ceiling fans.

5. Good magnetic performance: Although the magnetic energy product is not as good as high-end rare earth magnets, its high coercivity 

can ensure that the magnetic field remains stable under motor operating temperature and load changes, and is not easily demagnetized, 

meeting the long-term reliable operation needs of ceiling fans.

6. Corrosion resistance: The characteristics of the plastic coating and ferrite itself make it have good environmental corrosion resistance.

Working principle in ceiling fans

This injection molded ferrite magnetic ring is firmly installed on the rotor (rotating part, usually directly connected or forming a blade 

support structure) of the ceiling fan.

The controller of BLDC motor (electronic circuit on the stator side) will precisely control the current of the stator winding.

The rotating magnetic field generated by the stator winding interacts with the permanent magnet rotor (provided by injection molded magnetic 

rings) to generate sustained and efficient electromagnetic torque that drives the rotor to rotate.

The precise distribution of magnetic poles on the magnetic ring enables the controller to accurately sense the rotor position (usually through 

Hall elements), achieving smooth, spark free electronic commutation (compared to brushed motors), which is the key to achieving high 

efficiency, low noise, wide speed regulation, and long lifespan.

High Kos injection molded ferrite magnetic ring rotor, with its lightweight, high pole count, integrated structure, high cost-effectiveness, and stable 

permanent magnet performance, has become a key technical component to promote the popularization of BLDC ceiling fans. It not only reduces 

manufacturing costs, but also ensures the core user experience of efficient, energy-saving, quiet, stable, and long-lasting operation of ceiling fans. 

It can be said that it silently rotates at the core of the fan, driving the comfortable breeze of modern homes.