ASeminar

ON

“AIR BEARING IN HIGH PRECISION SYSTEM”

By Mr. KUMBHAR AKSHAY

CONTENTHISTORYINTRODUCTIONWORKING APPLICATIONSADVANTAGES /DISADVANTAGESCONCLUSION

HISTORYAir bearings are not a new technology

In 1828 Rev. Wills published a work in the Cambridge

Philosophical Society entitled “On the Pressure Produced on a Flat

Surface When Opposed to Stream of Air Issuing from an Orifice

in a Plane Surface”.

In 1904 air bearings were patented by G Westinghouse in vertical

steam turbine

The technology was commercialized when IBM used air bearing

spindles to produce large hard disc drives during the 70’s.

Last decades brought high accuracy demands in production

equipment applications.

•AIR BEARING

•An air bearing is a non-contacting system

where a gas film (typically air) acts as the lubricant

and supports the two surfaces in relative motion.

• As they are contact-free, air bearings

avoid the traditional bearing-related problems of

friction, wear, particulates, and lubricant handling.

•FRICTION Less Friction as compared to rolling And plain bearing

• WEARIBILITY Materials used in other bearing eventually gets used up with time, which requires replacement.

• LUBRICATION Unlike other bearing ,no lubrication is required.

USE OF AIR BEARINGS

•STIFFNESS:

A 6” diameter bearing running at 60psi actually has a stiffness greater

than 2,000,000 lb/in with a load of 1,000 lbs

•LOAD CAPACITY:

•When compensation is used to increase bearing stiffness, the average

pressure under the bearing is usually about 50 percent of the input supply

pressure. Air bearings can therefore generally be considered to be 50

percent efficient with regard to input pressure.

Types of air bearing• There are basically two types of air bearing:

1)Aerostatic : a) Air Caster b) Porous Media c) Orifice2)Aerodynamic: a) Foil bearing

Aerodynamic Bearing

Aerostatic Bearing

WORKING• Deflated :

In the deflated stage, the air bearing , it is resting on the floor with most of the weight being supported by the center load pad.

• Inflated :The second image shows the air bearing in an inflated form

after it has formed a seal with the floor surface. At this stage, the load has not been engaged to float away from the floor.

WORKING

• Load Lifted On Air : The above image shows the air bearing after it has engaged and floated the load. Compressed air will then start to escape from the bearing diaphragm into the area that is being contained by the floor seal. • The weight of the load causes the compressed air escapingout of the air bearing to force downward onto the floorsurface thus causing the load to float away from the floor.

Applications in High Precise System

•CMM•Automotive technology•Adjustment slider for optics production•Inspection Devices•Linear Drives•Medical Technology•Precision Machine Tools•Many more

CMM

•A machine which takes readings

in six degrees of freedom and displays

these readings in mathematical form is

known as a CMM.

•It requires very high and precise readings

•The probe which moves in X,Y, & Z

direction is controlled by Air bearing.

Medical technology

•Fat- and oil-free drives for respirators, stick-

slip-free movements of scanners or

a high rotary speed of large rotors have all

been achieved with air bearings.

•Air-guided computed tomography.

Linear drives

Precision measurement stageHigh-accelerated Doppler driveDrive for production machine

Production technology•Air bearing for the adjustment of components:

With air-guided units, optical components can be arranged

to have the same diameter on a rotary table.

•Adjustment slider for optics production:

The linear slider, which is air-guided and statically determined,

guarantees a high-precision positioning of the optical

component before grinding

Testing Equipment

•Many of the most accurate friction testing machines use air

bearings to eliminate mechanical contact friction.

•Being non-contact, air bearings are insensitive to high frequency

short travel applications.

ADVANTAGES

• GREATER PRECISION

• HIGH SPEED

• INCREASED TOOL LIFE

• IMPROVED SURFACE FINISH

• LONG BEARING LIFE

• CLAENLINESS

DISADVANTAGE

• HIGH GEOMETRY ACCURACY DURING

MANUFACTURING.

• CLEAN AND DRY SUPPLY OF PRESSURIZED AIR.

• HIGH PRICING.

• REQUIRE SOME KIND OF POWER CONSUMPTION

CONCLUSION•It is a technology that improves accuracy, resolution, smoothness

and dynamic response performance over rolling element bearings

• It is Viable clean solution for high speed applications.

• These advantages turn them into a clean and environment

Friendly bearing solution for various high-speed applications

such as optical scanning equipment and machine tool spindles

for PCB drilling and micro-milling.

References•Tobias Waumans, Jan Peirs, Farid Al-Bender, Dominiek Reynaert(2011) “Air bearing for

high speed applications” Vienano

•Crăcăoanu1 and F. Bremer(2008)” Air bearing in high precision system”

•Manoj Kumar Sharma, Gohil Priyank(2013)” Study of Dynamic Characteristics and Design

Analysis of Bush & Spindle of Ultra-Precision Aerostatic Bearing” IJSR

•http://www.newwayairbearings.com/design/technical-resources/new-way-technical-

reports/tech-report-1-air-bearing-comparison

•https://en.wikipedia.org/wiki/Air_bearing

•AIRFLOAT” How air bearings work” Decatur LLC · 2230