Can air bearings really wear without friction?

What is an air bearing?

When most people talk about bearings, they usually think of ball bearings. In this type of bearing, the fixed and moving surfaces are isolated by a series of lubricating balls. These balls move along special tracks or raceways. Perhaps the most common application is for an axle to rotate within a fixed hub, such as the drive shaft on the front wheels of a car or bicycle.

In air bearings, the ball is replaced by an air cushion. Perhaps one of the most familiar applications of air bearings is the Hovercraft.

The huge fan blows air under the Hovercraft, and prevents the air from escaping through the elastic rubber skirt. The High-pressure area generated below the Hovercraft can support the weight of the hull, thus making it float on the air cushion. The huge air cushion not only supports the weight of the ship, but also acts as a soft spring to make the ship float smoothly on rough land or water surfaces.

The same principle can be applied to shaft bearings. Inject high-pressure air into the gap between the shaft and the fixed bearing. The gap is very small (approximately 0.01 millimeters), allowing the air pressure in the gap to remain constant. Moreover, this narrow gap significantly reduces the "elasticity" of the air cushion, allowing the shaft to be very precisely fixed, which can only produce low dynamic eccentricity. Due to the low friction force, the shaft can rotate freely, and the air pressure ensures that the shaft does not come into contact with the fixed bearing surface.

The most commonly used gas medium for air bearings is air, which can also be nitrogen, hydrogen, helium, carbon dioxide, etc. according to different needs. Nowadays, in some advanced mechanical equipment, bearings with higher accuracy, longer service life, and greater load-bearing capacity are required, and air bearings can meet such requirements.