Types And Selection Of Bearing Lubrication

 

Grease plays a vital role in bearings. As a lubrication part, it can significantly improve the smooth operation of bearings and effectively extend the service life of bearings. Different brands and working conditions require different greases with different properties. Choosing the right grease is crucial for the long-term use of the bearing.

There are three main types of lubricants for bearings: oil, grease and solid lubricants. In practical applications, the most common ones are lubricating oil and grease.

• Lubricating oil: liquid with good fluidity, heat dissipation and lubrication properties. Widely used, suitable for bearings of various speeds and loads.
• Grease: semi-solid with good sealing and anti-bleed properties. Suitable for medium and low speed, high temperature, heavy load and occasions requiring good sealing.
• Solid lubricants: Mainly used as additives for oils and greases to improve their extreme pressure, anti-wear and high temperature resistance. It can also be used alone for special working conditions.

So, how to choose between the two? This mainly depends on the dn value of the bearing. The dn value is calculated by multiplying the inner diameter of the bearing (d, unit: mm) and the rotational speed (n, unit: r/min), which indirectly reflects the circumferential speed of the bearing.

• When the dn value of the bearing is less than (1.5~2) × 10^5, grease is usually the first choice. Because grease has high adhesion and stability, it can provide long-lasting lubrication at low speed or stationary conditions.
• When the dn value is greater than (1.5~2) × 10^5, lubricating oil is more suitable. Because lubricating oil has lower viscosity and higher fluidity, it can better meet the lubrication needs of high-speed running bearings.

 

Overall

For bearings that have clear requirements for bearing rotation torque, choose oil lubrication:

Oil lubrication usually provides a lower coefficient of friction, thereby reducing rotational torque.
Suitable for occasions requiring high-precision control and low energy consumption.

For high-speed, ultra-high-speed, high-precision, cross-contact ball, ceramic ball structure bearings, choose oil lubrication:

Oil lubrication can effectively dissipate heat and reduce the heat generated by the bearing due to high-speed rotation.
Suitable for bearings requiring high precision and long life.

There are standard and professional oil injection equipment, choose oil lubrication:

The use of professional oil injection equipment can ensure regular replacement and replenishment of lubricating oil and ensure the lubrication effect of the bearings.

When using the environment with impurities, high temperatures, corrosion, conductivity, etc., choose grease lubrication:

Grease is not easy to lose and can provide better sealing effect to prevent impurities from entering the bearing.

Grease has stable performance at high temperatures and is suitable for high temperature environments.

Some greases have anti-corrosion properties and are suitable for use in corrosive environments.

Grease has good insulating properties and is suitable for situations where electrical conduction needs to be prevented.

In short, when selecting the lubrication method of the bearing, it is necessary to comprehensively consider the working conditions, usage environment, maintenance requirements and other factors of the bearing to select the most suitable lubrication method.