Radial air-bearing modules do not constrain rotary motion using a 360° housing as is the case with rolling-element bearings. Instead they are positioned in combinations of three or four segments to support a rotor over just a small percentage of its circumference….

Radial air bearings can handle extremely high speeds thanks to their lack of friction. A general rule of thumb is that an air bearing will have only 10% of the load capacity of similar-sized rolling-element bearing but will have 10 times the speed capability and 100 times less friction….

Typically, radial rolling-element bearings have an inner and outer race that goes 360° around the rotating body. These races and the rolling elements they contain must be fit with a high degree of precision. The ability to manufacture parts with this type of precision has been the exclusive domain of bearing manufacturers.

Radial air bearings built as modules change this paradigm dramatically. Modular-radial air bearings support the rotor from a small percentage of the circumference. So the relative size between the rotor and the radius on the bearing is not critical. This means you can buy the radial air bearings and machine races on the rotor yourself, if need be….

Read the full article here: http://machinedesign.com/article/modular-air-bearings-for-motion-control-0721