Method for manufacturing spark plug and caulking metallic mold

摘要

A method for manufacturing a spark plug, the spark plug comprises: a cylindrical metal shell having a portion to be caulked and a tool-engaging portion that is to be attached on an engine; an insulator that is inserted into the metal shell and extends axially; and a caulking metallic mold, the method comprising caulking the portion to be caulked to be fixed to an outer circumferential face of the insulator with the caulking metallic mold, wherein the caulking metallic mold comprises a face, the face comprising a hard carbon film that comprises an amorphous carbon phase, and the face is contact with or sliding to the portion to be caulked.