SHAPES OF NANO-GROOVES AND RIDGE SHAPES ON MICRO-BEARING SURFACES
Journal Title: Tribologia - Year 2009, Vol 227, Issue 5
Abstract
In micro-bearings, where journal diameter has values up to 1 millimetre and the height of the micro-bearing gap has the largest value 1 micrometer, the intelligent features are attained by the groove and ridges on the sleeve and journal surfaces. The average groove depth and ridge height has a value of about 100 nm. The grooves have various geometrical shapes and are lying on the superficial layer of the sleeve and on the journal and are situated in circumferential and longitudinal directions of the cooperating bearing surfaces. The journals have additionally various geometrical shapes; however, in this paper, we are restricted to the cylindrical bearings only. Such grooves and ridges change in real form the height of the super thin, micro-bearing gap where the journal has various shapes. The geometrical shapes of the grooves and the cylindrical, conical, parabolic, hyperbolical geometry of the bearing journal has substantial influence on the hydrodynamic pressure distribution values and friction forces. Using the unit Heaviside‘a function and Fourier series expansions, the present paper shows the various formulae for an analytical description of the various shapes of grooves, which enables one to perform the numerical calculations of the hydrodynamic pressure, carrying capacities, and friction forces. The grooved and ridged gaps have applications in Computer Hard Discs Drivers (HDD) microbearings.<br/><br/>
Authors and Affiliations
Krzysztof Wierzcholski
Keywords
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