Abstract
In the oil-air lubrication applied to the high-speed spindle supported with a set of ball bearings, very severe noise is emitted so that the high-pressure air supplied through a couple of thin nozzles may collide with steel balls which are rolling at high speed. In this paper, the sound noise radiated from the spindle unit has been measured, changing theflange shape of the tool holders, the supplied air pressure, the number of nozzles and so on. A special spindle supported by magnetic bearings is also used in the experiment. From those experimental results, it is confirmed that the collision air causes such sound noise.
