A method and apparatus is provided for allowing a molecularly thin film to be
established
on a surface of the gas fluid dynamic bearing. The film can be controllably replenished
so that the problem of liquid lubricant starvation is overcome. A suitable non-sludging
lubricant of low surface tension is held in a porous reservoir within the stationary
portion of the bearing. This fluid migrates out of the reservoir to coat the contiguous
bearing surfaces. Alternatively, the lubricant may be held in a porous reservoir
within the rotating portion of the bearing; due to centrifugal force, as the rotating
portion spins, the fluid is spun out and coats the opposite non-rotating surface.
The reservoir may be replaced by a singular reservoir such as a simple hole, depression,
cavity or groove filled with lubricant. The liquid may also migrate by capillary
force through natural surface asperities or roughness by texturing the surface
to promote capillary migration; or the distribution of the lubricant is accomplished
by evaporation and condensation. The reservoir may be located in a region of the
bearing that reaches a relatively higher operating temperature than the wear surfaces
of the bearing. The transport of the lubricant then occurs by evaporation at the
wanner reservoir, and condensation at the cooler bearing surface.