How to choose the viscosity of the commutator grease

Update:21 Jun 2021

Viscosity is a key physical and chemical index. Proper selection of oil viscosity will reduce the internal friction of the grease, which will damage the surface of the commutator transmission gear and reduce the noise and vibration of the transmission system. Then, what is the viscosity of the grease Is it more appropriate?

The viscosity of the commutator grease is maintained by the base oil and the viscosity modifier. Among them, the viscosity of the base oil is related to the molecular formula and content. The average content is large, and the viscosity of the product oil is greater.

A good viscous agent should have high viscosity increasing ability, good cutting reliability, and excellent ultra-low temperature characteristics and thermal oxidation stability.

For greases with other viscosity types, if non-special base oils and poor viscosity indexing agents are used, although they can exceed a certain viscosity specification after formulation, the characteristics such as viscosity temperature and cutting reliability are not good. There is no required application cycle time.

The commutator is composed of carbon brushes and commutation rings. The motor carbon brushes are referred to as carbon brushes. Because of the rotation of the motor rotor (centrifuge rotor), the carbon brushes rub against the commutation ring from beginning to end, and they are in the commutation phase. It can also cause spark discharge in an instant, so the carbon brush is a part of the DC brushless motor.
In order to improve the service life and operational reliability of brushless DC motors and reduce the noise and interference signals of brushless DC motors, brushless DC motors are gradually replacing brushed motors. Generally, AC motors do not need a constant electromagnetic field, so there is no need for commutators and carbon brushes; however, the volume of AC motors is usually relatively large. The motors used in electrical products are usually all AC motors, such as electric fans, fully automatic washing machines, refrigerators, central air conditioners, etc., and there are no motor carbon brushes, but DC brushless motors are also used, such as many electric razors, kitchen appliances, etc. Electrical appliances, electric vehicles, etc. often have motor carbon brushes, that is, DC motors.
The appearance of the carbon brush of the motor is different, and the square is more common in the motor, and it is placed on the wall of the carbon brush. There is a certain working pressure between the motor carbon brush and the commutator. The structure of the large and medium-sized carbon brush is very complicated, and the small and medium-sized carbon brush is very simple. Most of the raw materials of carbon brushes are made of high-purity graphite in order to increase the conductivity. It is also made of copper-containing high-purity graphite. High-purity graphite has excellent conductivity, soft color and wear resistance.

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