11 lubrication methods for bearings

Manual lubrication

This is the most primitive method of using an oiler to supply oil when the lubricating oil in the bearing is insufficient.

However, this method is difficult to maintain a certain amount of oil, and there is a high risk of forgetting to refuel due to negligence. It is usually only used in situations with light loads, low speeds, or intermittent movements. It is best to install a dust cover or ball valve on the refueling hole and use felt, cotton, wool, etc. as a filtering device.

Drip lubrication

Usually used for light and medium load bearings with a circumferential speed of less than 4-5m/s, approximately a certain amount of lubricating oil is supplied from the container through holes, needles, valves, etc. The most classic is the oil drip cup, and the amount of oil dripping varies significantly with the viscosity of the lubricating oil, bearing clearance, and position of the oil supply hole.

Oil ring lubrication

The lubricating oil from the oil pool is carried into the bearing by a ring that is hung on the shaft and can rotate (only suitable for the lubrication method of horizontal shafts). It is suitable for medium and high-speed bearings with a diameter greater than 50mm. The oil ring is preferably seamless. When the bearing aspect ratio is less than 2, only one oil ring can be used, otherwise two oil rings are required.

Oil rope lubrication

Relying on the capillary and siphon action of the oil rope, the lubricating oil in the oil cup is introduced into the bearing, mainly used for light and medium load bearings with a circumferential speed less than 4-5m/s. In addition, the oil rope can play a filtering role throughout the entire process.

Oil pad lubrication

By using the capillary action of the oil pad, the lubricating oil in the oil pool is applied to the surface of the shaft diameter. This method can keep the friction surface clean frequently, but dust can also block the pores and cause insufficient oil supply. The oil supply for oil pad lubrication is usually only 1/20 of that for oil lubrication.

Oil bath lubrication

This lubrication method involves immersing a portion of the bearing in lubricating oil, which is commonly used for thrust bearings on vertical shafts and not for radial bearings on horizontal shafts.

Splash lubrication

The lubricating oil splashed up by the tapping of rotating parts in the oil tank is used to supply bearings, suitable for higher speed bearings.

Spray lubrication

The lubrication method of atomizing lubricating oil and spraying it on the friction surface is suitable for high-speed bearings.

Pressure oil supply lubrication

Relying on the pressure of the lubrication pump to supply oil to the bearings and recycle the lubricating oil flowing out of the bearings into the oil pool for recycling is the most stable and efficient lubrication method, suitable for high-speed, heavy-duty, and important sliding bearings.

Circulating oil lubrication

Use an oil pump to transport the filtered oil to the bearing components, and then filter and cool the lubricating oil after passing through the bearings before use. Due to the fact that circulating oil can take away a certain amount of heat and cool the bearings, this method is suitable for bearing components with higher rotational speeds.

Spray lubrication

Use an oil pump to inject high-pressure oil into the bearing through a 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 element and cage also form a airflow of surrounding air at a relatively high rotational speed. It is difficult to send lubricating oil into the bearing using ordinary lubrication methods. At this time, high-pressure spraying must be used to spray lubricating oil into the bearing, and the nozzle should be placed between the inner ring and the center of the cage.

Bearing lubrication is a continuous task, and the replacement cycle of lubricating oil is based on the different service conditions and oil quantities of the bearing.

In general, when used in a good environment with low dust and operating temperature below 50 ℃, it should be replaced once a year. When the oil temperature reaches 100 ℃, it should be replaced every 3 months or less.