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In the medical field, advances in modern surgical techniques dictate an almost unparalleled level of precision that can often mean the difference between a successful operation and catastrophe. To this end, high precision ball bearings are used in a wide variety of medical applications ranging from x ray tubes, CT scanners, dental equipment, and the robotic equipment used for cosmetic surgery.
While you might have known that precision is important in many respects, you might not have realized how it applies to you every day. From the precise robotic components that manufacture to exact specifications the products you use every day to the ultra precise dental equipment used to repair your teeth, precision ball bearings help make it happen better and with more accuracy than ever before.
What are air bearings?
An air bearing is a system where an air film acts as the lubricant that separates the two surfaces in relative motion. Unlike conventional (Journal bearings, ball bearings etc.) bearings, air bearings utilize a thin film of pressurized air to provide a non-contacting load bearing interface between the two surfaces in relative motion. Being contact free, air bearings provide an edge of overcoming usual problems in conventional bearings like wear, friction and lubricant handling. It also offers a distinct advantage in high speed machinery applications and precision positioning.
The air gap that acts as a lubricating film of the bearing is achieved by supplying an air flow through the bearing face and into the bearing gap. This air gap is achieved with the use of an orifice or a porous media that restricts or controls the air flow into the bearing gap. The design of restricting the air flow is such that, even though the air is continuously escaping from the bearing gap, the restriction of pressurized air through the gap is sufficient to have enough air that maintains the gap. It is this gap of restricted pressurized air under the bearing that supports the operational load. If there were no restriction of pressurized air then the floating load would reach higher than required resulting in improper functioning and higher air consumption. This controlled flow of pressurized air is referred to as air bearing compensation. It is employed to adjust the bearing with respect to height of lift, working load and stiffness.
Why use air bearings?
Fluids are of two types namely liquids and gasses. In terms of lubricating bearings the difference between the two is essentially the viscosity. We know that liquids have much higher viscosity than gasses. When we consider the fact that gasses having very low viscosity than liquids, it can be applied in lubricating bearings. This also implies that lower the viscosity, lower will be the load bearing capacity. But considering the extremely low viscosity of gasses let us have air as lubricating agent in this case. Air lubricating bearings operate with near zero static and running friction, whereas liquid lubricating bearings have much higher friction in the bearings which result in heat generation. Heat generation in bearings is a major concern which can be avoided using air bearings.
As discussed earlier air bearings require a controlled pressurized air for proper operation which means that a very high accuracy can be obtained during its motion. Using air as a lubricating fluid the cleanliness of the operating surroundings can be achieved. The other exclusive benefits of using air bearings are elaborated in further chapters.
Types of Air Bearing
There are three kinds of air bearing technology:
1 Aerostatic bearings:
Aerostatic bearings work with an external pressurized air source. This air pressure is introduced into to the bearing gap by precision grooves, holes, steps or porous compensation techniques as discussed earlier. As aerostatic bearings have a pressurized air source they can maintain an air gap when there is no relative motion between the bearing surfaces.
2.Aerodynamic bearings: