Guide bush and method of forming hard carbon film over the inner surface of the guide bush

Abstract

A hard carbon film (15) is formed directly or through an intermediate layer for enhancing adhesion over an inner surface (11b) of a guide bush (11) for holding a workpiece (51) rotatably and axially slidable on an automatic lathe at a position near a cutting tool, to be in sliding contact with the workpiece (51) or directly or through an intermediate layer for enhancing adhesion on the surface of a superhard lining fixed to the inner surface (11b). The guide bush (11) has remarkably enhanced durability and prevents damaging the workpiece (51) and seizing that makes a machining operation impossible even when the guide bush (11) is used for an extended period of time and when the automatic lathe operates for heavy machining. The hard carbon film (15) having satisfactory adhesion to the inner surface (11b) can be efficiently formed in a uniform thickness over the inner surface (11b) by placing the guide bush (11) in a vacuum vessel, extending an auxiliary electrode in the center bore of the guide bush (11) and producing a plasma of a gas containing carbon.

Dependencies are inferred from the claim text.