1. Oil Cup Drop Lubrication
A lubrication method where oil is dripped onto the bearing through the oil throttle port of an oil cup. Oil cup drop lubrication features a simple structure, easy operation and oil saving, and the oil supply can be adjusted via the oil throttle port. It is generally recommended to drip 1 drop of oil every 3-8 seconds; excessive oil supply will cause an increase in bearing temperature. Its disadvantages include certain requirements for lubricating oil viscosity (high-viscosity lubricants cannot be used) and the lack of heat dissipation function. This lubrication method is suitable for low-speed, light-load and low-temperature working conditions.

2. Oil Bath Lubrication
A lubrication method where the bearing is partially immersed in lubricating oil, and the oil is carried to other parts of the bearing as it operates. Oil bath lubrication is one of the most commonly used and convenient lubrication methods.
Considering the stirring loss and temperature rise during oil bath lubrication, there is a certain limit to the immersion depth of the bearing in lubricating oil for horizontal shafts; the oil level is usually controlled near the center of the lowest rolling element of the bearing. Oil bath lubrication provides sufficient lubrication, but the oil supply is difficult to adjust; without a filter device in the oil tank, impurities are easily carried into the bearing and cause damage. It is generally suitable for low or medium-speed working conditions and is commonly used for low-speed bearings.
Experience Summary: A detachable stiffener can be installed at the bottom of the bearing housing to reduce stirring loss or enhance heat dissipation. For horizontal shafts, the static oil level should be slightly lower than the center of the bearing's lowest rolling element; for vertical shafts, the static oil level should cover 50%-80% of the rolling elements. If the bearing temperature in the oil bath system is high, the lubrication system can be replaced with a drop, splash or circulating oil lubrication system.

3. Splash Lubrication
A lubrication method where oil is splashed onto the bearing by other moving parts. The oil supply of splash lubrication is not easy to adjust, and the lubricating oil level should not be too high, otherwise it is easy to cause stirring loss and temperature rise, and may also carry impurities in the oil tank into the bearing, leading to bearing damage.
In splash lubrication, oil is splashed onto the bearing by a rotating body (impeller or "oil slinger") mounted on the shaft, and the bearing itself is not immersed in oil.
Experience Summary: In gearboxes, gears and bearings often share a single oil tank, and the gears can act as oil slingers. However, since the viscosity of gear oil may not meet the bearing requirements and the oil contains particles generated by gear wear, a separate lubrication system or method can be adopted to extend the service life of the bearing.

4. Circulating Oil Lubrication
A lubrication method where lubricating oil is drawn from the oil tank by an oil pump and delivered to the parts of the bearing requiring lubrication, then the lubricating oil returns to the oil tank through the oil return port and is recycled after filtration.
Circulating oil lubrication provides sufficient lubrication with easily controllable oil supply, and has strong heat dissipation and impurity removal capabilities. It is suitable for scenarios requiring heat dissipation and impurity removal, as well as high-speed, high-temperature and heavy-load working conditions, with high reliability, making it an ideal lubrication method. However, this method requires an independent oil supply system with relatively high manufacturing costs, which consists of an oil pump, cooler, filter, oil tank, oil pipe and other components. Circulating oil lubrication includes oil injection, forced lubrication and oil mist lubrication, which are classified from different perspectives.

5. Oil Mist Lubrication
A lubrication method where lubricating oil is mixed with compressed air in an oil mist generator to form oil mist from a small amount of lubricating oil, which is then delivered to the lubrication area of the bearing.
Oil mist lubrication features low stirring loss and temperature rise, oil saving and few impurities in the oil. The air flow generated during oil mist injection has a certain cooling effect and can effectively prevent impurities from entering or discharge them. However, the lubrication device of this method has a high cost and has certain requirements for the viscosity of the oil used (generally not exceeding 340mm²/s), otherwise the atomization effect cannot be achieved. In addition, if the sealing is not tight during lubrication, part of the oil mist may escape into the air and cause environmental pollution; an oil-gas separator is required to collect the oil mist when necessary. Oil mist lubrication is suitable for high-speed working conditions.

6. Oil Injection Lubrication
A lubrication method where lubricating oil is injected into the bearing through high-pressure spraying. When the bearing operates at high speed, the rolling elements and cage also rotate at a high speed, forming an air vortex around the bearing. With ordinary lubrication methods, it is difficult for lubricating oil to reach the lubrication area; on the other hand, the centrifugal force generated by high-speed operation makes it difficult for lubricating oil to stay in the lubrication area. To ensure a sufficient but not excessive supply of lubricating oil to the high-speed rotating bearing, lubricating oil must be forcibly injected into one end of the bearing for lubrication and then flow back to the oil tank from the other end.
In the design of the lubrication system, the high-pressure nozzle should be located between the inner ring and the center of the cage, and the lubricating oil should be thrown out of the raceway by centrifugal action. For effective bearing lubrication, the injection speed of lubricating oil should not be lower than 15m/s.
In terms of operating speed, oil injection lubrication is often used for bearings operating at high speed under light or medium load; in terms of the bearing force direction, it is often used for bearings on vertical or inclined shafts, and the lubricating oil is usually directly injected into the bearing.

7. Oil-Air Lubrication
Oil-air lubrication is usually suitable for high-speed bearing operation scenarios. The oil-air lubrication system mixes a small amount of lubricating oil with gas at a certain pressure and then delivers it to the bearing. This method is suitable for high-speed working conditions (such as machine tools) and is rarely used in the oil refining and chemical industry.