Talking about the Advantages and Disadvantages of Gas Lubricated Bearings

The so-called gas lubricated bearings refer to the use of gas lubricants for lubrication of interactive bearings, our common gas lubricant is air. In use, the mechanism of gas-lubricated bearings forming bearing film is the same as that of liquid-lubricated bearings. Therefore, gas lubricated bearings have the following advantages and disadvantages when used.

Advantages of Gas Lubricated Bearings

1. High speed

The speed of small helium turboexpander has reached 650 000 r/min, the linear speed is 238 m/s, and the DN value has reached 455 x 106 mm/r/min.

2. High precision

Gas film has the function of error homogenization. Its accuracy is two orders of magnitude higher than that of rolling bearings, and its vibration is small and noise is low.

3. Low Friction Loss

The gas viscosity is only one thousandth of the lubricant viscosity, so the friction torque caused by the internal friction of the gas film is three orders of magnitude lower than that of the oil film.

4. Wide temperature range, energy antigen radiation

High temperature resistance can be up to 300 - 500 C, and gas bearings can still work when the temperature is as low as 10K.

5. Non-pollution

Lubricating gases are usually air or inert gases, which emit into the atmosphere without pollution. The bearing has low vibration and noise, and does not pollute the environment.

6. Long life

Gas hydrostatic bearing has no direct contact with metal and its theoretical life is infinite. Considering other constraints, it should generally be more than 104 hours. There exists intermetallic friction in the start-stop moment of hydrodynamic gas bearing, and its service life is affected to a certain extent, but it is also over 3000 hours.

Defects of Gas Lubricated Bearings

1. Lower carrying capacity

Compared with similar oil-lubricated bearings, the bearing capacity of gas-lubricated bearings is about 1-2 orders of magnitude lower. According to the carrying capacity per unit area, oil-lubricated bearings are generally (0.5-2) MPa, while gas-lubricated bearings are only (0.02-0.04) MPa.

2. Poor reliability

On the one hand, gas-lubricated bearings are prone to instability, resulting in common air hammer vibration and eddy instability. On the other hand, gas lubricated bearings are often stuck, held or bitten.

3. The manufacturing precision is high and the cost is high.

Because the gas film is very thin, usually in the range of several microns to tens of microns, it requires high manufacturing accuracy and increases the cost of parts. In addition, there are special technological requirements for processing spiral grooves, throttle holes and porous materials, which increase the difficulty and cost of manufacturing.

4. Strict working conditions

Gas lubricated bearings require a high cleanliness working environment and strict compliance with operating procedures to ensure that the bearings work normally and do not cause accidents. Therefore, its wide application and commercialization are limited to a certain extent.