**Lubrication**

78 Tribology in Engineering

[24] Rickerby D. G., Macmillan N. H., The Erosion of Aluminium by Solid Particle

[25] Shipway P. H., Hutchings I. M., A Method for Optimizing the Particle Flux in Erosion

[26] Anand K., Hovis S. K., Conrad H., Scattergood R. O., Flux Effects in Solid Particle

Impingement at Normal Incidence, Wear 1980; 60, 369-382.

Testing with a Gas-Blast Apparatus, Wear 1994; 174, 169-175.

Erosion, Wear 1987; 118, 243-257.

**Chapter 6** 

© 2013 Belforte et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 Belforte et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**High Speed Rotors on Gas Bearings:** 

**Design and Experimental Characterization** 

Gas bearings are employed in a variety of applications from micro systems to large turbomachinery. As they are free from contaminants if supplied with clean air, gas bearings and pneumatic guide-ways are often used in food processing, textile and pharmaceutical industries. The new research works are focused on expanding the applications of gas bearings, in particular at very high speeds. Dental drills for example operate at speeds of over 500 krpm and it seems that a limit for gas bearings without cooling is 700 krpm [1]. Nevertheless in [2] a spindle with 6 mm diameter that operated at 1.2 million rpm is

Because of the extremely close manufacturing tolerances that air bearings require and the lack of standard large scale production models, their costs are not at all competitive with those of the rolling bearings in common use. In order to determine whether the initial costs associated with investing in gas bearings will result in savings, each type of technology should be carefully examined. The service life of gas bearings is in fact practically unlimited,

Many investigations of air bearings have been conducted using experimental, numerical and theoretical approaches with analytical models, e.g. [3-6]. However research is still necessary to improve stiffness, load capacity and stability. At present, research studies potential designs individually to seek the main requirements for a particular application. For dynamic gas bearings, applications are currently limited to those involving low power, though an increasing amount of work is focusing on developing reliable solutions for higher-power uses. Machine tool applications, for example, require a stiffness comparable to those of the rolling bearings in common use; in very high speed applications operational stability is essential. In many cases, parameters such as the number and diameter of supply holes, their arrangement, and supply system geometry come into play. Where rotor stability under low

G. Belforte, F. Colombo, T. Raparelli, A. Trivella and V. Viktorov

Additional information is available at the end of the chapter

since they require almost no maintenance and do not wear.

http://dx.doi.org/10.5772/50795

**1. Introduction** 

described.

**Chapter 6** 
