Abstract: An electric discharge machining method for machining a core pin for a resin die using an electric discharge machine including a secondary electrode for molding of a round-bar shaped machining electrode. The electric discharge machining method includes a step of executing generating electric discharge machining for cutting out a schematic shape of the core pin from a work with the machining electrode, a step of transferring a shape element of the secondary electrode to the machining electrode and molding the machining electrode for diesinking electric discharge machining, and a step of applying the diesinking electric discharge machining to the work cut out in the schematic shape of the core pin using the machining electrode molded for the diesinking electric discharge machining.

Abstract: An electric discharge machining method for machining a core pin for a resin die using an electric discharge machine including a secondary electrode for molding of a round-bar shaped machining electrode. The electric discharge machining method includes a step of executing generating electric discharge machining for cutting out a schematic shape of the core pin from a work with the machining electrode, a step of transferring a shape element of the secondary electrode to the machining electrode and molding the machining electrode for diesinking electric discharge machining, and a step of applying the diesinking electric discharge machining to the work cut out in the schematic shape of the core pin using the machining electrode molded for the diesinking electric discharge machining.

Abstract: An electrode material for electrical discharge machining made of a W—Cu alloy containing at least 40% by weight of W, at most 15% by weight of an additional element or a compound thereof, and a balance of Cu, contains, as the additional element or the compound thereof, at most 10% by weight of particles selected from an alkali metal element, an alkaline-earth metal element and a rare-earth element, and an oxide, a hydroxide, a nitride, a boride and a sulfide of the elements. For example, the additional element or the compound thereof is an oxide or a hydroxide of each of Ba, Nd and Ce. The particles have a mean particle diameter of less than 3 ?m or a mean interparticle spacing of at most 20 ?m. At least 30% of W particles contained in the alloy preferably have a particle diameter of at most 1 ?m. In addition, not more than 10% by weight of Ni can further be contained.

Abstract: An electric discharge machining apparatus for supplying machining electric power to a gap between an electrode (1) and a workpiece (2). The apparatus includes a gap dimension detection device (8) for detecting a dimension of the gap, a gap average voltage detection device (11) for detecting an average voltage of the gap, a gap dimension correction device (13) for correcting the dimension of the gap, and a gap dimension correction starting device (12) for starting the gap dimension correction device (13) when a first comparison between a detected gap dimension and a predetermined allowable value and a second comparison between a detected gap average voltage and a predetermined reference average voltage are made and the gap dimension detected by the first comparison is larger than the predetermined allowable value and the gap average voltage detected by the second comparison is smaller than the predetermined reference average voltage.