11-02-2013, 02:32 PM
AIR BEARING TECHNOLOGY
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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 imagesetting - 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 radial and 500 kg axial, and bearing
stiffnesses of up to 12kg/μm radial and 50 kg/μm axial.
Greater Precision
Air bearings provide extreme radial and axial rotational precision. Since there is no mechanical contact,
wear is minimal, ensuring accuracy remains constant over time.
Air bearing spindles, by their manufacturing construction, are inherently accurate in rotation. Special
manufacturing techniques enhance this accuracy to give extreme rotational and axial precision. Air bearing
spindles have been designed to achieve rotational accuracy of less than 0.1 microns TIR in both axial and
radial directions. As there is no mechanical contact between the rotating shaft and the static support, there
is nothing to wear out, ensuring the accuracy remains constant over time – an important feature for
manufacturers using statistical process control.
Typical synchronous radial runout values: < 10 microns (PCB drilling spindle, high speed).
Typical asynchronous radial runout values: < 0.025 microns (Disk test spindle, low speed).
Increased Tool Life
The use of air bearings means tool life can be greatly extended.
The lack of vibration and high rotational accuracy means drills, cutters, grinding wheels and boring tools
have a much longer life – reducing maintenance and running costs. In particular, in the PCB drilling
industry where drill diameters as small as 50 microns are now used, only air bearing spindles are capable
of running at the required speeds to ensure acceptable tool life.
Typical increase in grinding wheel life: 1.5 to 4 times dependant on application & wheel type.