A netizen reported that the end ring of the motor rotor they produced melted after running for a period of time, and asked what the reason was.

From the motor cases I have come into contact with, this is the first time that the rotor end ring has completely melted. For cast aluminum rotors, the end ring is an important component of the rotor circuit and physical components.

In order to analyze this problem, we first understand the role of the rotor end ring: 

(1) The cast aluminum rotor end ring can provide protection to prevent the rotor from being damaged by the external environment, such as dust and moisture. 

It can play a role in isolation and sealing to ensure the normal operation of the rotor. 

(2) It can improve the stability of the rotor and increase the stability and stiffness of the rotor. It can also increase the mass and moment of inertia of the rotor, making the rotor more stable at high speed and reducing the risk of vibration and resonance. 

For most cast aluminum rotors, heat dissipation fan blades and balance columns are added to the end ring as important components for motor heat dissipation and dynamic balancing. 

(3) The cast aluminum rotor end ring has good thermal conductivity and can help the rotor dissipate heat quickly. The cast aluminum rotor end ring can effectively improve the heat dissipation performance of the rotor and keep the rotor temperature within a safe range.

 (4) Cast aluminum rotor end rings have good wear resistance and corrosion resistance, which can extend the service life of the rotor. In the friction and wear between the rotor and the stator, the rotor end ring can protect the rotor and reduce wear and damage.

In addition to mechanical functions, the motor rotor end ring also carries an important component of the rotor circuit. Current passes through the end ring. When the end ring is designed to be small, if the corresponding current density is large, the end ring will heat up. 

In addition, if the aluminum is impure, there will be heating problems due to high resistance. From the perspective of ventilation and heat dissipation, the motor temperature rise and poor heat dissipation will also cause heating.

Therefore, for the serious heating problem of the rotor end ring, a comprehensive analysis and solution should be made from the aspects of end ring design, material compliance, and casting process defects.