Abstract: An improved method of machining slots and material feed holes in a molding die such as an extrusion die designed to form a honeycomb structure of ceramics employed as a catalyst carrier of a catalytic converter for automotive vehicles. In one of the preferred embodiments, shallow holes are drilled in a die material and subjected to electrochemical machining to remove material from the bottoms of the shallow holes so that they communicate with the material feed holes without any burrs. In the other embodiment, the slots are cut using a rotary cutter in a given order which will balance reaction forces exerted on the cutter from both side walls of each slot to minimize deformation of the cutter during cutting of the slots, thereby preventing the slots from being curved undesirably.

Abstract: An improved method of machining slots and material feed holes in a molding die such as an extrusion die designed to form a honeycomb structure of ceramics employed as a catalyst carrier of a catalytic converter for automotive vehicles. In one of the preferred embodiments, shallow holes are drilled in a die material and subjected to electrochemical machining to remove material from the bottoms of the shallow holes so that they communicate with the material feed holes without any burrs. In the other embodiment, the slots are cut using a rotary cutter in a given order which will balance reaction forces exerted on the cutter from both side walls of each slot to minimize deformation of the cutter during cutting of the slots, thereby preventing the slots from being curved undesirably.