Air bearing technology
Technical specifications follow later on
Based on its longstanding expertise and know-how in the field of air-bearing development and production, Systemtechnik Hölzer GmbH (SH) features both of the most common air-bearing technologies, with either orifices or porous material. Given the proven advantages of bearings with orifices for air-distribution as compared to the most common porous materials in the market, the following details exclusively refer to the former air-bearing type.
The different layouts of SH air-bearings with orifices unrestrictedly meet the requirements up-to-date air-bearing technology is confronted with, such as:
- maximum precision positioning & guiding accuracy
- highest speed-rates / acceleration
- 100 % emergency running properties in case of air-failure
- no wear - maintenance free
- free of friction – no stick-slip
- no lubricants – no contamination
- suitable for clean-room application
These properties cover the most demanding applications of air-bearings in the field of precision coordinate measuring & high-speed production machinery, among which the most important are electronics-components manufacturing, high-resolution scanning & measuring and precision cutting/milling machinery.
The SH air-bearings, designed with an anodized alloy housing function either as carrying bearing, guiding bearing or balancing bearing.
Commonly acknowledged determinants for air-bearing qualities are:
1. Load rate / capacity utilization
2. Stiffness / height of air-cushion gap
3. Air-bearing body oszillation
4. Economic efficiency
1. The rate of capacity utilization is high by nature of the bearings` design because the max. air floating pressure evenly covers most of the bearings surface (“face”) before it equalizes to atmospheric pressure.
2. More important than the bearings` load capacity is its stiffness which is defined by the effect on the height of the air-cushion gap in case the bearing is exposed to different degrees of strain (i.e. acceleration). The basic stiffness of an air-bearing, like other properties, is determined by design. A constant stiffness-ratio, which is often altered due to dimensional fluctuation of the orifices, is guaranteed by employing a ruby in the SH orifices which ascertains a constant air flow rate. The bearings` air-distributing notches, which divide the surface into three segments to assure the anti-tipping properties of a three-legged table, encase a highly plane and lapped surface. The latter belongs to the SH core competences and is an integral part of the SH general service range.
3. SH bearings are characterized by an optimally tuned dimensional relation between the bearings` chamber and the appropriate height of the air-gap (correlation between air feeding pressure, orifice-diameter, load-rate). Basically, any air-bearing can be destabilized by altering subject parameters. In case the beared machinery-components show weight-tolerances, it is essential to re-establish an even, identical air gap pressure among all bearings forming a closed system. SH provides a solution to this problem with adjustable air-bearings equipped with a fine-tuning device.
4. The SH air-bearings` competitive edge with regards to their performance together with their comparably moderate air consumption make them first choice to economically complete high-precision positioning tasks.