14-08-2012, 10:28 AM
AIR BEARING TECHNOLOGY
AirBearingTechnologybriefv2.pdf (Size: 5.17 MB / Downloads: 365)
INTRODUCTION
Introduction to Westwind Air Bearings
Westwind Air Bearings is universally recognised as a world leader in the design and
manufacture of air bearing spindle systems. Westwind technology has been successfully
applied across a broad spectrum of industries throughout the world - from paint spraying to
pre-press image setting - while in today's PCB industry there are more Westwind drilling
spindles in use than any other.
Westwind's success is based on its ability to solve problems that arise from customers' use of
conventional bearing systems, that are operating beyond the limits of their capabilities. Such
solutions may be found in an air bearing spindle specifically designed to meet customer
needs, or in an existing spindle from one of Westwind's established product ranges.
Air Bearing Technology Overview
• An air bearing is a non-contacting system where air acts as the lubricant that
separates the two surfaces in relative motion.
• There are two types of air bearing systems: aerostatic and aerodynamic.
• Air bearing technology offers real advantages to applications where the demand for
accuracy, speed and reliability is crucial.
The performance given by Westwind air bearing technology regularly exceeds the
parameters offered by conventional bearing systems, with speeds ranging from 0 to 300,000
rpm, powers range from 10w to 30kw, load capacities of up to 150 kg
SECTION 1: AIR BEARING TECHNOLOGY
What is an Air Bearing?
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.
The Basic Principles of an Air Bearing Spindle
Figure 1: Cutaway of an air bearing PCB drilling spindle
Types of Air Bearing
There are two main kinds of air bearing:
1) Aerostatic:
Externally pressurised: A separate external supply of air is fed under pressure between the
two surfaces being kept apart.
It is a continuous flow system where pressurised 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.
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2) 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.