Linear Motion Applications
The modularity of New Way air bearings is particularly well-suited to the creation of tailored linear motion solutions. In fact, there are many ways to create frictionless linear motion with New Way products, including flat round or rectangular air bearings; vacuum preloaded air bearings; air bushings; even air bearing slides assemblies, like New Way's dovetail, end-supported or boxway slides. You'll find more specific information about these applications below.
Linear Motion with New Way Flat Round or Rectangular Air Bearings
Round pucks and rectangular bearings are available from stock in a range of common sizes, allowing for any number of detailed arrangements. Since New Way air bearings are easy to incorporate into systems, linear motion solutions can often be fabricated far less expensively than off-the-shelf assemblies. The ease of adjustability of the bearings, high speed and acceleration, quick settling time, along with superior accuracy in fly height control, allow for superbly consistent motion and repeatability, easily configured to your desired need.
New Way air bearings float on a 5µm layer of air, creating truly non-contact motion that has virtually zero friction. This requires that the flatness of the guide surface be greater than 50% of the fly height of the bearing, thereby ensuring that the bearings remain truly non-contact. This is not as difficult as it may seem, since many common applications involve the use of granite plates, or blocks which are readily available from suppliers at less than 10% of this value. Other viable surfaces include hard-coated aluminum, ceramics, stainless steel, and even glass. Because the air bearings are non-contact, they average any surface deviations out, improving linear motion even further. Also, since there is zero friction, motion control resolution is nearly infinite, since the coefficient-of-static-friction is zero.
When designing a solution with air bearings, care must be taken to create an arrangement that forms a constraint based upon the needs of the application. Since air bearings create a floating body, that body must be constrained in space, in order to perform in the desired axis. Often, a feature can be incorporated on the guide surface to constrain motion to the desired axis, as shown in the figure at left. Numerous other permutations and arrangements can also be utilized.
Linear Motion with New Way Vacuum Preloaded Air Bearings
One such permutation is the use of Vacuum Preloaded Bearings (VPLs), especially where pre-loading is difficult or impossible. These flat round components use vacuum to pre-load the bearing. By adjusting the vacuum and pressure, the fly height and stiffness can be optimized. The result is that only one flat guide surface is necessary, whereas opposed bearing preloading requires two flat guide surfaces that are parallel.
Linear Motion with New Way Air Bushings
When the need for low coefficients of friction and high motion control resolution on rail type systems is required, New Way air bushings may be used. These bushings are available in a range of sizes from 13 mm to 75mm, and in English sizes from ¼" to 3.00", allowing for common shaft size mounting. Since Ra 0.4mm (16µ in) surface finish shafting is commonly available, creating precision single axis linear motion is easy.
By utilizing a tube of porous media, in which there are millions of sub-micron holes, and applying an air pressure of 60PSI (0.4 MPA), an 8 µm (0.0004") layer of air is created between the bushing and shaft. The bushing is designed so that a self-centering force is created by the air flow, allowing for true 360° non-contact motion on round shafting. The bearing surface, being non-contact on the shaft, and coupled with a parallel shaft and bushing, creates precise motion in one axis, and eliminates the heat and vibration commonly associated with roller contact, and recirculating ball linear way arrangements. The micro resolution then available allows for precision applications previously unattainable in rail mounted stages. With compliant O-ring type mounting, misalignment of parallel shafts in linear stages is possible up to .002" over the length of the shaft.
Linear Motion with New Way Slide Assemblies
Finally, New Way offers three different types of standard slide assemblies, which combine an accurate guide surface with an air slide ready-fit for installation. This provides the user with the convenience of integrated guide and bearing systems.
These slides have a straightness of motion and dynamic response often an order of magnitude better than conventional rolling element bearings. New Way end supported air slides, dovetail slides, and boxway slides provide a local straightness (in X and Z) of 250 nanometers (0.25 microns) per 25mm travel (10 micro inches per inch), maximum error (global) 2 microns per 1000mm travel (80 micro inches per yard).
For further assistance with linear motion applications, please refer to the New Way Air Bearing Application and Design Guide.