An air bearing is a non-contacting system where a gas film (typically air) acts as the lubricant that separates the two surfaces in relative motion.   

Basic Principles of an Air Bearing Spindle

What is an air bearing?

Fig 1 – Cutaway of an air bearing PCB drilling spindle.

Types of Air Bearing

Aerostatic

  • Externally pressurized: A separate external supply of air is fed under pressure between the two surfaces being kept apart.  
  • It is a continuous flow system where pressurized gas from the source flows through restrictors into the clearance between the bearing surfaces escaping to the atmosphere at the outside edges of the bearing.  
  • Types: Simple orifice fed, Pocketed orifice, Slot fed and Porous.  
What is an aerostatic air bearing?

Aerodynamic

  • Self-generating: The supporting film is generated by the relative motion of the two surfaces being kept apart.  
  • An aerodynamic bearing can be of several types.  The design characteristics differ greatly between journal and axial bearings and they can suffer problems of instability.  
  • Types: Simple cylinders, Tri-lobe, Grooved (axial / herringbone / spiral) and Stepped.  
What is an aerodynamic air bearing?

Typical bearing clearance and tolerance

Bearing Systems Comparison Table

Bearing systems comparison table

Further Reading