Aerostatic bearings
Clean compressed air is fed through orifices, grooves, slots, porous media, or compensating restrictors. Load support exists before the axis moves.
Air bearings · gas bearings · precision motion
Precision motion on a microscopic film of air.
Aerostatic and aerodynamic bearings remove rolling-element contact for metrology, semiconductor, optical, spindle, and ultra-precision motion.
Film thicknessMicroscopic + non-contact
Pressure sourceExternal air or surface speed
Primary strengthsRepeatability · cleanliness
Primary risksSupply loss · crash · debris
01 / Operating principle
Pressure is distributed across the bearing face.
An air bearing carries load on a controlled gas film. The surface geometry, restrictor behavior, supply pressure, flow, clearance, flatness, and load determine stiffness and stability.
Because there is no rolling-element recirculation or lubricant film contamination, air bearings can deliver smooth motion and exceptional repeatability. The trade is system sensitivity: a small particle, geometric error, pressure change, or crash event can consume a large share of the operating clearance.
Aerodynamic bearings
Relative surface motion generates gas-film pressure. Foil bearings and self-acting gas journal bearings need sufficient speed before full lift develops.
Linear air bearings
Flat pads or guideways support translation with very low friction and no rolling-element pitch error. Straightness depends on the reference surfaces.
Rotary + spindle bearings
Journal, thrust, and conical air films support high-speed or ultra-precise rotation for metrology, machining, scanning, and optical systems.
02 / Restriction strategy
How the air enters shapes performance.
| Architecture | Behavior | Design focus |
|---|---|---|
| Discrete orifice | Air enters through individual calibrated holes or inserts. | Orifice balance, groove geometry, pressure distribution, clogging. |
| Porous media | Flow is distributed through a permeable bearing face. | Permeability uniformity, filtration, surface preparation, crash resistance. |
| Slot or groove fed | Machined restrictions spread supply around the load area. | Manufacturing accuracy, flow stability, pneumatic hammer avoidance. |
| Vacuum preloaded | Opposing pressure and vacuum create bidirectional stiffness on one-sided stages. | Supply balance, flatness, vacuum capacity, contamination control. |
| Opposed pads | Air films on both sides constrain motion and establish preload. | Gap setting, structural loop, thermal stability, assembly alignment. |
03 / Specification
Microns make the mechanical system.
- Load + moment
- Define force direction, center of pressure, overturning moment, transient loads, and desired stiffness.
- Travel or rotation
- Stroke, diameter, speed, acceleration, duty cycle, reversal, and cable or hose forces influence architecture.
- Accuracy
- Straightness, flatness, runout, tilt, repeatability, positioning resolution, and allowable error motion need separate targets.
- Air supply
- Pressure, flow, filtration, dew point, oil content, regulator behavior, facility variation, and loss-of-air response.
- Reference surfaces
- Air bearings average local surface error but still follow long-wavelength flatness, straightness, and thermal distortion.
- Crash protection
- Hard stops, landing pads, coatings, sacrificial surfaces, sensors, and startup logic protect microscopic clearances.
Failure modes
Debris ingestion, wet or oily air, blocked restrictions, insufficient supply, geometric error, thermal bow, pneumatic instability, overloading, impact, and uncontrolled touchdown can damage an air-bearing system. Cleanroom compatibility does not remove the need for air preparation and material review.
Have load, travel, accuracy, and facility-air data?Open an air-bearing brief
04 / Applications
Where smoothness and cleanliness dominate.
Coordinate + inspection
Reference-quality motion without recirculating-element error or stick-slip.
Wafer + reticle stages
Clean motion, tight error budgets, scanning, and controlled thermal behavior.
Scanning + positioning
Low disturbance forces, smooth velocity, and angular repeatability.
Ultra-precision spindles
High-speed rotation with low synchronous error and no lubricant contamination.
Calibration + force systems
Low friction, predictable stiffness, and reduced hysteresis in sensitive measurements.
Imaging + laboratory motion
Quiet, clean, repeatable positioning where contamination control matters.
05 / FAQ
Air-bearing questions.
How does an air bearing work?
It supports a moving surface on a very thin pressurized gas film. Aerostatic bearings use an external air supply; aerodynamic bearings generate pressure through relative motion and geometry.
Do air bearings have zero friction?
They eliminate sliding and rolling contact during normal operation, but gas shear, pressure flow, seals, cables, and auxiliary systems still create force and energy loss.
What air quality is required?
Most aerostatic systems need clean, dry, regulated air. Filtration, dew point, oil carryover, pressure stability, and flow capacity should be specified with the bearing supplier.
Can air bearings carry heavy loads?
They can carry substantial loads when area, pressure, preload, structure, and restrictor design are appropriate. Load capacity alone does not establish stiffness, accuracy, or crash margin.