airbearing

Airbearing refers to a bearing that uses a thin film of pressurized air to separate mating surfaces, providing load support with extremely low friction and minimal wear. The air film allows relative motion with high stiffness and precision, making air bearings suitable for ultra-clean, high-accuracy applications.

Types of air bearings fall into two broad categories. Aerostatic (or aerostatic bearing) uses an external supply of pressurized air delivered through orifices or porous surfaces to generate lift independent of motion. Aerodynamic (or self-acting) bearings rely on high-speed motion of the moving surface to generate air lift from the surrounding airflow. Hybrid designs combine elements of both. Bearings can be radial, thrust, or a combination, and are used in precision stages, spindles, chucks, and linear guides.

Operating principle is based on a controlled air gap, typically micrometers to tens of micrometers thick. The load capacity and stiffness depend on supply pressure, bearing geometry, and gap clearance. Aerostatic bearings require a continuous air supply and maintain load regardless of speed, while aerodynamic bearings depend on relative motion to generate lift and may have different performance envelopes at varying speeds and loads. Fluid cleanliness, filtration, and temperature control are important for consistent performance.

Advantages include very low friction, high stiffness, excellent positional accuracy, zero wear, and clean operation without lubricants. They enable high-speed operation and minimal contamination, which is valuable in metrology, semiconductor manufacturing, optical systems, and high-precision CNC and machining.

Limitations involve the need for a reliable compressed-air supply, potential sensitivity to dust and leaks, and higher initial and maintenance costs.