Machine Design

Think Lube-Free Air Bearings For Low Friction And High Speed

The next time you're ready to design a system using rolling-element bearings or replace worn bearings, give some thought to air bearings. They ride on air bushings and are interchangeable with rolling-element designs that run on round shafts. Air bearings have several advantages over rolling-element versions. For instance, their noncontact operation means the shaft does not have to be hard.

This allows using a wider variety of shaft materials.

Air bearings can provide rotary and linear motion. The bushings mount inside a bore or housing on O-rings that are compliant enough to let the bushings self-align. When high stiffness is required the bearings can be set in place using a precision potting procedure. Air bushings, housings, and end mounts are available for easy assembly of custom stages.

Although air bushings are commonly used in voice-coil linear-motor-driven stages, they are well suited in any motion application requiring low friction, oil-free operation, high speed, or unlimited service life. Stainless-steel or flush-chromed shafts are recommended to avoid rust.

This information supplied by New Way Machine Components Inc., Aston, Pa.

Why Use Air Bearings Instead Of Roller Bearings?
Lots of reasons. For example:

  • Zero static friction allows infinite resolution and high repeatability.
  • Zero wear comes from noncontact operation and results in consistent machine performance and low particle generation.
  • Straight motion is generated throughout the life of air bearings because they adjust to rough, irregular, or worn surfaces.
  • Silent and smooth air-bearing operation almost eliminates noise and vibration. This is especially noticeable in sensitive machine output, such as scanner resolution.
  • Higher damping in air bearings comes from their squeeze-film
  • damping effect. They are actually a fluid-film bearing. This produces higher dynamic stiffness and better controllability.
  • Eliminating lubricants eliminates the problems associated with oil. In dusty environments, such as dry machining, ways are dry and bearings are self-cleaning because positive air pressure pushes dust away. In contrast, oil lubrication becomes a lapping slurry.
  • High speed and acceleration results because there are no balls or rollers to slip at high acceleration.

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