Effect of air rarefaction on the contact behaviors of air lubricated spiral-groove thrust micro-bearings

•The contact behavior of an air bearing is studied considering air rarefaction.•The air rarefaction shows a significant increase in the asperity contact force.•The groove depth has a major effect on the contact behavior of the bearing.•Larger standard deviation of asperity height generates lower air bearing force.

The contact behaviors of an air lubricated spiral-groove thrust micro-bearing were investigated. The air bearing force and asperity contact force of the bearing were calculated considering the effect of air rarefaction and surface roughness. The effect of the groove depth and the standard deviation of asperity height was discussed. The results showed that the air bearing force decreases significantly when the air rarefaction is considered. This then leads to an increase in asperity contact force. The depth of spiral grooves and the standard deviation of asperity height also significantly affect the asperity contact force of the bearing.