Bearings are widely used in various types of machinery, which to a certain extent affects whether the machinery can operate normally. 

Choosing the correct lubrication method can reduce the internal friction and wear of the bearing, prevent burning and play a lubricating role.

Its lubricating effect is as follows:

(1) Reduce friction and wear

In the mutual contact parts of the rings, rolling elements, and cages that make up the bearing, metal contact is prevented and friction and wear are reduced.

(2) Prolong fatigue life

The rolling fatigue life of the bearing is extended when the rolling contact surface is well-lubricated during rotation. Conversely, if the oil viscosity is low and the thickness of the lubricating oil film is not good, it will be shortened.

(3) Discharge frictional heat and cool down

Circulating oil supply method, etc. can use oil to discharge heat generated by friction, or heat transmitted from the outside, for cooling. Prevent the bearing from overheating and prevent the lubricating oil itself from aging.

(4) Others

It also has the effect of preventing foreign matter from intruding into the bearing or preventing rust and corrosion.

Bearing lubrication methods are divided into grease lubrication and oil lubrication.

Too give full play to the function of the bearing, it is important to adopt the corresponding lubrication method according to the service conditions and purpose of the bearing.

Bearing lubricating grease

Lubricating grease is a lubricant composed of base oil, thickener, and additives. When choosing, you should choose lubricating grease that is very suitable for the service conditions of the bearing. Due to the different brands of lubricating grease, there will be great differences in performance, so when choosing, you must pay attention. Commonly used greases for bearings include calcium-based grease, sodium-based grease, calcium-sodium-based grease, lithium-based grease, aluminum-based grease, and molybdenum disulfide grease. The amount of grease filled in the bearing is suitable to fill 1/2-1/3 of the internal space of the bearing. At high speed, it should be reduced to 1/3. Too much grease will easily increase the temperature of the bearing during operation.

Lubricating grease selection

When selecting grease according to the working temperature, the main indicators should be the dropping point, oxidation stability, and low-temperature performance. The dropping point can generally be used to evaluate the high-temperature performance, and the actual working temperature of the bearing should be 10-20°C lower than the dropping point. The operating temperature of synthetic grease should be 20-30°C lower than the dropping point. When selecting grease according to bearing load, for heavy loads, grease with small needle penetration should be selected. In addition to small needle penetration when working under high pressure, it also has high oil film strength and extreme pressure performance. When selecting grease according to environmental conditions, calcium-based grease is not easily soluble in water and is suitable for dry and less-moisture environments.

Bearing oil lubrication

Under the condition of high speed and high temperature, oil lubrication can be used when grease lubrication is no longer suitable. Through the circulation of lubricating oil, a lot of heat can be taken away. Viscosity is an important characteristic of lubricating oil. The size of viscosity directly affects the fluidity of lubricating oil and the thickness of the oil film formed between friction surfaces. The viscosity of lubricating oil at the working temperature of the bearing is generally 12-15cst. The higher the rotation speed, the lower the viscosity should be selected, and the heavier the load should be, the higher viscosity should be selected. Commonly used lubricating oils include mechanical oil, high-speed mechanical oil, steam turbine oil, compressor oil, transformer oil, cylinder oil, etc.

Oil lubrication methods include:

a. Oil bath lubrication

oil bath lubrication is the most common lubrication method, suitable for low and medium speed bearings, part of the bearing is immersed in the oil tank,

The lubricating oil is carried by the rotating bearing parts, and then flows back to the oil groove, and the oil level should be slightly lower than the center of the lowest rolling element.

b. Oil drop lubrication

Oil drop lubrication is suitable for bearing parts that require a quantitative supply of lubricating oil. The amount of oil drop is generally one drop every 3-8 seconds. Too much oil will cause the temperature of the bearing to increase.

c. Circulating oil lubrication

use an oil pump to deliver the filtered oil to the bearing.In the components, the lubricating oil after passing through the bearing is filtered and cooled to make it use. Since the circulating oil can take away a certain amount of heat, the bearing will drop

Temperature, so this method is suitable for bearing components with higher speed.

d. Spray lubrication

 Use dry compressed air to mix with lubricating oil through a sprayer to form oil mist, and spray it into the bearing. The airflow can effectively cool the bearing and prevent the intrusion of impurities. This method is suitable for the lubrication of high-speed, high-temperature bearing components.

e. Spray lubrication

Use an oil pump to inject high-pressure oil into the bearing through the nozzle, and the oil injected into the bearing flows into the oil groove through the other end of the bearing. When the bearing rotates at high speed, the rolling elements and the cage also make the surrounding air flow at a relatively high rotation speed. It is difficult to send the lubricating oil to the bearing with the general lubrication method. At this time, the lubricating oil must be sprayed by high-pressure injection In the bearing, the location of the nozzle should be placed between the inner ring and the center of the cage.