Image Number 8 for United States Patent #5976347.
A method of three-dimensionally microcutting a metal material suitable for molds is provided. An electrolyte is interposed between a work piece which is made of a conductive material, and an electrode. Through application of an electrolysis voltage between the work piece and the electrode with the electrolyte interposed between them, a passive state film is formed on the surface of a to-be-cut part of the work piece. Then, the passive state film on the surface of the to-be-cut part of the work piece is cut.