AIR BEARING APPLICATION AND DESIGN GUIDE
AIR BEARING APPLICATIONAND DESIGN GUIDEREVISION E -- JANUARY 2006New Way Air Bearings 50 McDonald Blvd. Aston, PA 19014 USA 610.494.6700 www.newwayairbearings.com
New Way Air BearingsAir Bearing Application and Design GuideTABLE OF CONTENTSPART I: UNDERSTANDING AIR BEARINGS .31. Introduction . 32. What is an air bearing? . 33. Why use air bearings? . 3Friction . 3Wear. 3Stiffness . 3Load Capacity . 34. Types of air bearing technology . 3Aerodynamic bearings . 3Aerostatic bearings . 3Orifice and Porous Media Technology. 35. Air Bearing Products . 3Flat Bearings (Pucks). 3Air Bushings. 3Vacuum Preloaded Bearings (VPLs) . 3Air Bearing Slides. . 3Radial Bearings. 36. Air Bearing Applications. 3Machines for the Image Setting Industry . 3Coordinate Measuring Machines . 3Testing Equipment . 3High Speed Equipment . 3Ultra accurate machine tools . 3Linear Stages. 3OEM . 3Custom Projects and Test Rigs . 3PART II: CHOOSING AIR BEARINGS .37. Selecting the right air bearing product for your application. 3 2006, New Way Air BearingsAir Bearing Application and Design Guide – Revision EPage 2 of 68
Air Bearing Application and Design GuideNew Way Air BearingsPART III: DESIGNING WITH AIR BEARINGS.38. Air Bearing Guides . 3Guide Surface Considerations. 3Surface finish . 3Local flatness . 3Holes in the guide . 3Seams in the guide way. 39. Stiffness and Preload . 310. Loads Acting on Air Bearing Systems . 3Gravity Loading. 3Payload distribution and mobility . 3Preloading with other air bearings . 3Dynamic Loading . 3PART IV: SETTING UP AND USING AIR BEARINGS.311. Flat Bearings . 3Mounting and Adjusting . 3Adjusting Main bearings. 3Adjusting Preload bearings. 3Typical Configurations . 312. VPLs . 3Vacuum Preloaded Air Bearing Technology. 3Kinematics and Elastic Averaging . 313. Air Bushings. 3Air bushing installation . 3Assembling an Air Bushing Slide. 3Typical Configurations . 314. Rotary Tables . 3PART V: ADDITIONAL INFORMATION .315. Air Supply. 316. Measuring flow . 317. Flow . 318. Plumbing . 319. Airflow through the bearing gap. 320. Air Supply Requirements. 3Technical Support: 610.494.6700www.newwayairbearings.comPage 3 of 68
New Way Air BearingsAir Bearing Application and Design GuidePART I: UNDERSTANDING AIR BEARINGS1. Introduction1.Bearing technology represents one of the age-old problems for mechanical engineers. Rollingelement bearings developed in the last century were a revolutionary improvement over the plainbearings that had been pushed to their limits in applications like electric motors and automobilewheels. Similarly, rolling element bearings are today being pushed to their technical limits by thedemands of applications like semiconductor manufacturing, high resolution scanning, and high-speedmachinery.Air bearings represent the next logical step in bearing design. Air bearings in general have a proventrack record having been employed in coordinate measuring machines for 20 years. The manytechnical advantages of air bearings such as near zero friction and wear, high speed and highprecision capabilities, and no oil lubrication requirements are powerful advantages for today'smachine designers. However, these benefits have not been more fully utilized to date because airbearings are difficult to manufacture and they have not been commercially available until recently.New Way Precision was founded ten years ago to pioneer the use of porous media technology andmake air bearings that are robust, simple to use, inexpensive, and available off-the-shelf.Figure 1 - Bearing Performance vs. CostThe purpose of this guide is to answer the common questions that designers have when firstconsidering air bearings, as well as to provide detailed information that will help ensure the successof your advanced application. This is believed to be the first such collection of information regardingthe selection, mounting, and application of commercially available air bearing products. 2006, New Way Air BearingsAir Bearing Application and Design Guide – Revision EPage 4 of 68
Air Bearing Application and Design GuideNew Way Air Bearings2. What is an air bearing?Unlike contact roller bearings, air bearings utilize a thin film of pressurized air to provide a ‘zerofriction’ load bearing interface between surfaces that would otherwise be in contact with each other(Figure 2). Being non-contact, air bearings avoid the traditional bearing-related problems of friction,wear, and lubricant handling, and offer distinct advantages in precision positioning and high speedapplications.The fluid film of the bearing is achieved by supplying a flow of air through the bearing face and intothe bearing gap. This is typically accomplished through an orifice or a porous media that restricts ormeters the flow of air into the gap, referred to in Figure 2 as R1. The restriction is designed such that,although the air is constantly escaping from the bearing gap, the flow of pressurized air through therestriction is sufficient to match the flow through the gap. It is the restriction through the gap, R2 thatmaintains the pressure under the bearing and supports the working load. If air pressure wereintroduced to the gap without restriction (R1), the flying height would be higher, the air consumptionhigher, and the stiffness would be lower than could be achieved with proper restriction. Thisrestriction is referred to as air bearing compensation. It is used to optimize the bearing with respect tolift, load, and stiffness for particular applications and will be discussed later in more detail.Threaded ball studfor easy adjustmentSlide HousingAir Bearing(Puck)Air filmAir Supply(60 PSI)Gap Restriction (R2)Guide SurfaceOrifice Restriction (R1)Figure 2 - Flat Air BearingTechnical Support: 610.494.6700www.newwayairbearings.comPage 5 of 68
New Way Air BearingsAir Bearing Application and Design Guide3. Why use air bearings?Because of their advantages over rolling element bearings, air bearings are a natural choice forapplications such as Coordinate Measuring Machines, precision machine tools, semiconductor waferprocessing machines, and other clean room, high speed, and precision positioning environments. Themain advantages of air bearings are listed below. Some of the specific concerns of the designengineer (friction, wear, stiffness, and load capacity) are then discussed in more detail.ZERO FRICTION.Because of zero static friction, infinite resolution and very high repeatability are possible.ZERO WEAR.Non-contact means virtually zero wear resulting in consistent machine performance and low particlegeneration.STRAIGHTER MOTION.Rolling element bearings are directly influenced by surface finish and irregularities on the guide. Beingnon-contact air bearings average these errors.SILENT AND SMOOTH OPERATION.Recirculating rollers or balls create noise and vibration as hard elements become loaded and unloadedand change direction in return tubes. This is especially noticeable in the resolution of scanners.HIGHER DAMPING.Being fluid film bearings, air bearings have a squeeze film damping effect resulting in higher dynamicstiffness and better controllability.ELIMINATES OIL.Air bearings do not use oil lubrication, eliminating the problems associated with oil. In dustyenvironments (dry machining) ways are dry and bearings are self-cleaning because positive air pressurepushes dust away. In contrast, oil lubrication becomes a lapping slurry.HIGH SPEEDS.High speeds - high acceleration. No balls or rollers to slip at high acceleration. 2006, New Way Air BearingsAir Bearing Application and Design Guide – Revision EPage 6 of 68
Air Bearing Application and Design GuideNew Way Air BearingsFrictionVariances in friction have always been at the heart of precision positioning problems, particularlywhen attempting to initiate or stop motion precisely. This is because especially in plain bearings, butalso in rolling bearings, the static coefficient of friction is higher than the dynamic coefficient of friction.In other words it takes more force to initiate motion than it does to maintain motion. So when a motorturns a screw to push a slide, the screw winds up and stores some of the energy because of the highstatic friction. When the slide starts to move, the friction falls and the screw unwinds, pushing theslide past its desired position. This phenomenon is known as ‘stick-slip’ and is most pronounced inplain way systems. However, it can also cause positioning or bandwidth issues even in machines withrolling element bearings and closed loop feed back.Today heavy machine tool slides can bepositioned within .0001” using rolling elementbearings because the difference between thestatic and dynamic coefficients of friction isreduced by an order of magnitude compared toplain bearings.But even rolling elementbearings are reaching their limits. For instance,in some areas of the electronics capitalequipment industry, positioning to even .00001”is considered too course.Rolling elementbearing manufacturers have started to reducetheir preloading (compromising stiffness) inwhat has become known as a ‘California Fit’ inan effort to meet these requirements, but thereare limits to how effective this can be.In air bearings there is no difference betweenFigure 3 - Coefficients of Frictionstatic and dynamic coefficients of friction so thestick-slip issue is completely eliminated. Friction in air bearings is a function of air shear from motion,so at zero velocity there would be zero friction making infinite motion resolution theoretically possible.Friction has a direct effect on efficiency. In fact one of the first air bearing patents applied for was byWestinghouse for use in vertical steam driven generating turbines. Westinghouse knew that becausethe viscosity of air is several hundred times lower than that of oil, he could reduce the energy loss dueto oil shear. Unfortunately for Westinghouse, at that time (1890) it was exceedingly difficult tomanufacture the large bearing surfaces to the high precision required for air bearings to work. Todaylarge turbines still use oil based hydrodynamic bearings, but many of the new micro turbines on theTechnical Support: 610.494.6700www.newwayairbearings.comPage 7 of 68
New Way Air BearingsAir Bearing Application and Design Guidemarket are employing aerodynamic bearing systems to improve efficiency. Friction also has an effecton precision. Remember the old saying, what are the three main sources of error in a precisionmachine? Heat, heat, and heat! Friction creates heat, which is a precision engineer’s worst enemy.For instance when a spindle heats up it grows axially. As the heat conducts into the headstock it willexpand and the center of rotation will grow away from the base. In most cases air bearings will createsignificantly less heat in a given application than a rolling element or plain bearing. This is not to saythat air bearings cannot create heat, as they can but relative speeds need to exceed 100 feet persecond before significant heat can be measured.WearMechanical wear is another thorn in the side of the design engineer. Advanced machines arerequiring faster speeds and higher reliability. In fact, there are machines currently on the market thatmake a billion moves per year. It is impractical to perform accelerated testing on such a machine soat best the engineer must employ speed, acceleration, and loading calculations in order to estimatethe life of the bearing. This problem is avoided with air bearings due to their non-contact nature.Speed, acceleration, and loading are not wear factors and they have no influence on the life of the airbearing.The mode of wear in an air bearing is erosion, so the cleanliness of the air has the greatest effect. Airbearings are immune to conventional notions of wear and will perform exactly the same in the 10thyear of operation as they did in the first, even after a billion cycles per year. This is a big advantagewhen it comes to machine reliability. Equipment builders that can say to their customers that wearhas been eliminated, as a variable that could affect their statistical process control will have a distinctcompetitive advantage. The lack of debris from wear and no need for oil lubrication due to the noncontact nature of air bearings also means that they are ideally suited for use in clean room, medical,pharmaceutical, and food processing environments. Air bearings also excel in dry dusty environmentssuch as salt or sugar factories, which can be highly corrosive. In these environments any oillubrication quickly becomes a lapping slurry. Air bearings have a self-purging effect with constant airexiting the bearing blowing away light dry dust. 2006, New Way Air BearingsAir Bearing Application and Design Guide – Revision EPage 8 of 68
Air Bearing Application and Design GuideNew Way Air BearingsStiffnessA common misconception about air bearings isthat they do not have the req
introduced to the gap without restriction (R1), the flying height would be higher, the air consumption higher, and the stiffness would be lower than could be achieved with proper restriction. . for easy adjustment Figure 2 - Flat Air Bearing Orifice Restriction (R 1) . the static coefficient of friction is higher than the dynamic .
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Jul 19, 2021 · Air Bearing Blower Air Bearing Centrifugal Blower Air Suspension Bearing Technology Self-developed patent winning core technology. 2 Ultra-high-speed air bearing ensures true oil-free and no mechanical friction. 3 The air bearing has tested 20,000 times of start and stop, the approval service life of semi-permanent. Energy conservati
Bearing type Canon Air Bearing AB36RV Canon Air Bearing AB50RV Canon Air Bearing AB50LRV Canon Air Bearing AB250R Rotation speed Max 15,000rpm Max 22,000rpm Max 10,000rpm 500 2,500rpm Encoder pulse 2,048 2,048 83,328 1,024 Jitter 0.
Air Bearing Technology Overview ¾ An air bearing is a non-contacting system where air acts as the lubricant that separates the two surfaces in relative motion. ¾ There are two types of air bearing systems: aerostatic and aerodynamic. ¾ Air bearing technology offers real advantages to applications where the demand for accuracy,
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contents 1. bearing failure analysis 3 1.1 determination of operating data 3 1.2 lubricant sampling 4 1.3 inspection of the bearing environment 4 1.4 assessment of bearing in mounted condition 5 1.5 dismounting the damaged bearing 5 1.6 assessment of the complete bearing 5 1.7 assessment of bearing components
4 TIMKEN METRIC TAPERED ROLLER BEARINGS BEARING DATA TIMKEN METRIC TAPERED ROLLER BEARINGS Bore Part Number Dimension Series (ISO 355) Bearing Dimensions Bore d O.D. D Width T B Width C mm mm mm mm mm mm 15 30302 2FB 15.000 42.000 14.250 13.000 11.000 17 30203 2DB 17.000 40.000 13.250 12.000 11.000 30303 2FB 17.000 47.000 15.250 14.000 12.000 20 File Size: 279KBPage Count: 20Explore furtherTapered Roller Bearing Catalog Timkenwww.timken.comTimken Tapered Roller Bearing Catalog - TIMKEN - PDF .pdf.directindustry.comTimken Metric Tapered Roller Bearing Catalogwww.timken.comTIMKEN METRIC TAPERED ROLLER BEARINGSwww.timken.comTimken-Tapered Roller Bearing Catalogue - THE TIMKEN .pdf.aeroexpo.onlineRecommended to you b
