Submicron positioning solutions for precision applications. The role of radial clearance on the performance of foil air bearings kevin radii u. Abstract a fundamentally precise and simple linear motion axis design is discussed where the attractive force from the linear motor is used to preload a carriage supported by six rigidly attached porous carbon air bearings. Hysteresis prediction including preloading effects fluid film bearing vi session 6h marcel mahnera, pu lia, andreas lehna, bernhard schweizera atechnical university darmstadt, department of mechanical engineering, institute of applied dynamics introduction. Study of the stiffness matrix of preloaded duplex angular contact ball bearings article pdf available in journal of tribology 14 october 2018 with 212 reads how we measure reads. As with all our products, the vacuum preloaded air bearings use porous media technology to provide no contact motion.
Army research laboratory, gleim research center, cleveland, ohio samuel howard gleim research center, cleveland, ohio brian dykas ohio aerospace institute, brook park, ohio prepared for the international joint tribology conference. As with conventional bearings, air bearings constrain the relative motion of a desired. S209001 vacuum preloaded air bearing090mm 6104946700. Atlas i series manufacturer of precision air bearings and. Pdf dynamic modeling method for air bearings in ultraprecision. The holding force of an air bearing for one solar panel averages 600 n. Ibs precision engineering vacuum preloaded air bearings. In contrast to conventional bearings, with this technique the air bearings require no manual or costly manufacturing. Development of magnetically preloaded air bearings for a. Mar 21, 2016 preload is critical in most highprecision and highspeed applications, particularly where rotational and positional accuracy is required, wallace says.
Always follow the original equipment manufacturers installation and maintenance guidelines. The combination of noncontact components results in a frictionless motion platform that offers the highest performance, quality, and life. The many technical advantages of air bearings such as near zero friction and wear, high speed and high precision capabilities. A linear air bearing stage with active magnetic preloads for. This article will provide an overview of bearing preloading in common radial and angular contact ball bearing applications. Linear motion along the yaxis is achieved with 4 preloaded 75 x 150 mm2 air bearings, along the sides of the granite guideway. Tapered roller bearings continued tapered roller bearings 316 clearances axialclearance as these bearings are always mounted in opposition, the axial clearance is determined by. Air bearings represent the next logical step in bearing design. However, bearing b is relieved of the axial preload force, and the axial dis placement under additional load is the same as it is for a bearing system without preload, that means it is determined solely by the spring constant c a, if the external axial force exceeds the value cq a w ka f0 1. Static performance of porous carbon air bearings can be predicted 5, and for commercially available bearings, design data bearing gap as a. Characterization of the axial and pitching stiffness of porous vacuum preloaded air bearings angelica ruszkowski1, kaan erkorkmaz1, gordon stubley1 1department of mechanical and mechatronics engineering university of waterloo waterloo, ontario, canada introduction demands for highresolution and highspeed.
Clean radial air bearings and guide surfaces when needed. A new foil air bearing test rig for use to 700 c and 70 000 rpm chris dellacorte national aeronautics and space administration lewis research center cleveland, ohio 445 summary a new test rig has been developed for evaluating foil air bearings at high temperatures and speeds. Extremely rigid structures with high natural frequencies. This article describes what is preloading, preloading of bearings, need for preloading of bearings.
Numerical and experimental investigations on preload effects. Eight aerostatic bearings with rectangular carbon porous pads are located under the table to support vertically and preloaded by four magnetic actuators attached at the corners, and four bearings are located on each side of the stage, similar to the conventional wraparound design for horizontal direction. Air bearing stages linear, rotary, and spherical replace mechanical contact by a thin air film, avoiding wear, friction. Flexure mounts provide bidirectional stiffness, a low pivot point, and infinitesimal angular adjustment for new way vpl air bearings. Oav vacuum preloaded air bearing utilize a combination of air pressure and vacuum, air bearings hold it down while simultaneously lifting from surface. The piglide mb air bearing stage is linear servo motor driven with fully preloaded air bearings and an integral optical linear encoder. Air bearings are a type of bearing that use pressurized air to create an air gap between two surfaces. Linear motion carriage with aerostatic bearings preloaded by. The preload of the air bearing and thus the gap height are also adjusted with this piston. Bearings apart from being mounted on the shafts and housings have to be preloaded properly for their proper functioning. Make vacuum preloaded spherical air bearings without. The oav vacuum preloaded air bearing combines the use of air pressure and vacuum to be held down while simultaneously being lifting from the surface for ultimite precision.
Since 1994, new way air bearings has been the market leader in porous media air bearing technology. Air bearings in general have a proven track record having been employed in coordinate measuring machines for 20 years. Air bearings also known as aerostatic or aerodynamic bearings are bearings that use a thin film of pressurized gas to provide a low friction loadbearing interface between surfaces. Superprecision cylindrical roller bearings, for example, can only be preloaded radially because of their design, while angular contact ball bearings or tapered roller bearings can only be preloaded axially. The vacuum preloaded air bearings are placed on the back side of the optic. Spring preloaded fag nonlocating bearing units spp 4 nonlocating bearing units spp spring preloaded nonlocating bearing units spring preloadedspp ar very costeffective, readytofit units with an integral sliding seat function, figure 1, figure 4. A new foil air bearing test rig for use to 700 c and. The naturally porous carbon substrate uniformly distributes. Flat circular vacuum preloaded air bearings performance physical properties installation requirements model part number load capacity, lbsn stiffness, lbsinch nm vacuum holding force at rated vacuum, lbsn flow rate, scfh slpm diameter, inches mm height, inches mm ball seat diameter, inches mm air vacuum. There are many ways to apply preload, as well as many benefits and potential problems with preload. Research laboratory the role of radial clearance on the. In this paper, we propose a linear motion stage designed with magnetically preloaded air bearings. An investigation to the design of vacuum preloaded air. The first article in this series described what preload is.
For the moment, we will examine a basic linear bearing with cross rollers making contact within a vgroove. Linear motion axes are ubiquitous in manufacturing. Air bearing application and design guide new way air bearings. Air bearing application and design guide new way air bearings technical support. The atlas i series stages employ fully preloaded air bearings with large bearing surfaces to provide excellent mechanical stiffness and load capacity. Piglide air bearing technology impact of nanotechnology. Air bearings can provide effectively zero friction, do not require lubricants. Air bearings are fluid bearings that use a thin film of pressurized gas to provide a low friction. By adjusting the vacuum and the pressure separately, the fly height and stiffness of these vacuum preloaded air bearings can be optimized. The twodimensional pressure distribution in each bearing pad is described by the reynolds equation for compressible fluids. Air bearings are the proven standard for superior smoothness of motion and positioning control in high precision applications. Hence axial adjustment of the bearing by any means is another methodology for the preloading of the bearings. Pdf study of the stiffness matrix of preloaded duplex.
The oav profile tseries rail guides are manufactured using premium grade aircraft quality material. I show how to make spherical, cylindrical, and flat bearings that are also vacuum preloaded, meaning the bearing is. The magnetic actuators for preloading air bearings were combined with permanent magnets and coils to adjust the air bearing clearance by actively controlling the magnetic force. If, under operating conditions, a bearing has radial play. This arrangement provides high stiffness in the ydirection, and also decreases gantry splay. Bearing preload is an axial or thrust load applied to a bearing that removes excess play. Vacuum is used to cancel the air bearing force while decreasing the air gap for better stiffness. We offer a variety of sizes which can easily be used to customize air bearing systems. As with conventional bearings, air bearings constrain the relative motion of a desired object to one or more axes. This article deals with the various types of preloading methods used for bearings. Vacuum preloaded bearings vpls are similar to flat air bearings but they utilize vacuum to provide preloading of the bearing against the guide surface. They comprise a standard spindle bearing with a double width outer ring. It is basically constraining the bearing axially in order to reduce the clearances in the bearing. A detailed elastogasdynamic model of a preloaded threepad air foil journal bearing is presented.
Follow all tolerance, fit, and torque recommendations. Design analysis porous graphite bearings were selected for the design because they are very damage resistant. The piglide mb air bearing stage is linear servo motor. Any reproduction, disclosure or use of this drawing or the information contained herein is expressly prohibited except as new way. Depending on the bearing type, preload may be either radial or axial. The air bearing stage system with the proposed active magnetic preload is shown in fig. Low profile, fully preloaded single plane designs with integrated pressure vacuum air bearings. Heres where youll see real customer applications, get a sense of how the product performs and possibly spark creative ideas for your next design. Sometimes the bearing area and vacuum area are separated by a groove which is connected to ambient pressure in order to prevent flow from the pressurized area to the vacuum ejected area. New way air bearings offers bearings that come preloaded with vacuum to give you more control over the fly height and air gap stiffness. Not only is less air used in vacuum preloaded air bearings when compared to orificebased air bearings, but the air is evenly distributed by the porous media.
Easy application new way makes air bearing components easy for anyone to apply. Pdf air bearings have been widely used in ultraprecision positioning stages due to. The two surfaces do not touch, thus avoiding the traditional bearingrelated problems of friction, wear, particulates. The airbearing components diameter 34 mm with integrated magnets are so small such that they are able to glide contactfree along conventional rolled sheet plates smoothly and with a bearing gap height of about 25. A new technique to make graphite air bearings without precision tooling. Vacuum preloaded vpl air bearings are generally designed by combining a collar bearing and a central area where vacuum is drawn figure 1. Bump and top foil deflections are herein calculated with a nonlinear beamshell theory according to reissner. Combining vacuum with air pressure, they offer advantages for a wide range of applications in a diverse group of markets and industries. Because the gap is kept small by a preload force, the air escapes to. This means that one bearing race can be moved radially and axially relative to the other.
The unique use of porous media in vacuum preloaded air bearings makes them ideal for clean room use. The air bearings are assembled by vacuuming the pads to two orthogonal planes, positioning the carriage above the pads, and then injecting epoxy between the bearings and. Why is preload necessary in some bearing applications. Preloaded magnetic actuators were combined with permanent magnets and coils to adjust the air. Air bearings provide advantages over mechanical bearings when vibrationfree motion is required, highly constant velocity control is crucial, and when angular repeatability and geometric performance must be optimal. Characterization of the axial and pitching stiffness of. This stage offers ultraprecision in a miniature package. Clean by applying alcohol to a clean, dry cloth and wiping surfaces thoroughly. Nearly every conventional bearing has an analogous air bearing form.
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