METHOD OF REMOVING HARD CARBON FILM FORMED ON INNER CIRCUMFERENTIAL SURFACE OF GUIDE BUSH

摘要

A guide bush (11) having a hard carbon film (15) on an inner circumferential surface thereof in slide contact with a workpiece is placed in a vacuum chamber (61) in which an anode (79) and a filament (81) are provided, with an auxiliary electrode (71) inserted in a central bore (11j) of the guide bush. The vacuum chamber (61) is evacuated while grounding the auxiliary electrode (71) or applying a DC positive voltage thereto. An oxygen-containing gas is then introduced into the vacuum chamber, and a DC voltage is applied to the guide bush (11) and the anode (79), and an AC voltage is applied to the filament (81), whereby a plasma is generated in the vacuum chamber (61). The hard carbon film (15) is thus etched and removed from the inner circumferential surface of the guide bush (11).