Advantages of Air Bearings
Today’s high-speed and ultra-precision machinery and tools must avoid friction to operate with high accuracy and reliability. While a variety of bearings are available on the market to reduce friction between machinery moving parts, each work differently and offer a different level of performance. Traditional roller bearings, for example, contact surfaces during operation and generate heat that results in wear and some levels of friction that can affect machine performance. Air bearings from New Way® offer superior performance over roller bearings.
Even orifice air bearings that maintain a thin film of pressurized air to avoid direct surface contact have their challenges. Constructed of hard-coated aluminum or stainless steel, orifice bearing surfaces are easily scratched. A scratch across a groove or orifice on the bearing face can result in a costly crash or impact fly height. Users also must carefully choose an orifice air bearing with the right number, size, and distribution of jeweled holes to maintain air stability during operation.
How Air Bearings Work
New Way Air Bearings incorporate Porous Media Technology™ that maintains a controlled and uniform distribution of air pressure across the bearing surface for greater stability and stiffness (see Graphic 1.) Because New Way Air Bearings are composed of porous carbon media, they are harder to clog and, even if nominally scratched, operate evenly. They also fly at small air gaps, making them crash tolerant.
Graphic 1: Comparison of orifice vs. porous media air bearing technology that features millions of sub-micron holes for better air distribution that results in greater stability and stiffness.
Here’s What the Experts Say about Air Bearings
According to Design World magazine, a primary benefit of air bearings is the elimination of friction-induced wear, heat generation, and need for lubrication. Without recirculating elements, air bearings achieve higher speeds than a ball or roller bearing. The publication also points out that the fluid film in air bearings compensates for small-scale errors for more accurate motion than mechanical bearings.
The following table outlines the performance differences between New Way Porous Media Air Bearings and conventional roller bearings:
|Porous Media Air Bearing||Rolling Element Bearing|
|Straighter motion for optimum positioning.||Momentum of balls amplifies unwanted bearing motion causing precision deviations.|
|High speeds an order of magnitude greater than conventional roller element bearings.||Contact with the rail or guideway and multiple ball velocities limit the speed capabilities. Balls or rollers can slip at high acceleration.|
|Smooth and silent operation without vibrations.||Recirculating rollers or balls cause velocity ripples that compromise stability and performance.|
|Zero friction and zero wear for consistent, long-term performance at higher resolution.||Balls show wear from mechanical contact resulting in inconsistent machine characteristics.|
|Elimination of lubricants and low particle generation avoid environmental contamination in clean rooms. In dusty environments, air bearings push away dust.||Oil lubrication required by rolling element bearings can puddle, contaminating the area.|
Because of their non-contact nature, porous media air bearings provide advantages that traditional rolling element bearings, or even conventional orifice air bearings, inherently cannot. Here you’ll find the performance of porous media air bearings compared to that of conventional rolling element bearings across eight critical characteristics.
When your application requires precision positioning, it is important to understand that rails and guideways often exhibit flatness deviations. Some of these are inherent…others may develop over time. Either way, the momentum of the balls in a rolling element bearing actually amplify the unwanted motion of the bearing. In fact, rail-ball contact further damages both…
A direct comparison of porous media air bearings and conventional rolling element bearings shows that, when using the latter, there is a significant amount of unwanted motion in all directions. This is because there are minute differences in the size of the balls themselves and the balls are also slightly larger then the clearance in…
Mechanical contact requires lubrication. Because conventional rolling element bearings rely on the movement of balls against a guide surface, lubrication is a standard part of ongoing equipment maintenance. But lubricant migrates to the guide surface, and also causes out-gassing, often effecting the process at hand or the environment. Maintenance is not only necessary, it can…
Conventional rolling element bearings are limited in their acceleration capabilities because of the rotating inertia of the balls in their guideways. These balls start and stop at inconsistent points. They slide, skip and skid. This causes precision problems, especially for applications with light loads over short distances. In a direct comparison, porous media air bearings…
There is an order of magnitude difference which separates the speed capabilities of conventional rolling element bearings from their porous media air bearing counterparts. Contact with the rail or guideway, and multiple different ball velocities, limit the speed capabilities of conventional rolling element bearings to 3-5 m/s. Porous media air bearings are a completely non-contact…
Any comparison with porous media air bearings must include a recognition of the constantly changing, multiple forces which act on the raceway integral to the function of the competitive rolling element bearing. The changing directions of the balls within this raceway result in velocity ripples which, in turn, compromise stability and impact performance. These velocity…
When it comes to wear, contact is, again, the differentiating factor between rolling element bearings and porous media air bearings. Quite simply, balls show wear from mechanical contact. Over their lifetime, this causes friction changes, resulting in inconsistent machine characteristics. In fact, in mechanical contact systems, wear is a function of load, acceleration, velocity, distance,…
The comparison between conventional rolling element bearings and porous media air bearings begins and ends with contact. Contact, and the resulting high stiction, often causes the rolling element bearing to overshoot its mark. This causes resolution problems, especially with light loads over short distances. New Way Porous Media™ air bearings are entirely non-contact, so there…
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