Abstract: A cutting tap includes thread ridges, roots formed between the respective axially adjacent pairs of thread ridges, and a plurality of deburring thread grooves arranged at a constant pitch toward the axial front side of the cutting tap from the rearmost ones of the roots in which the deburring thread grooves are formed, and formed such that a groove bottom diameter of the deburring thread grooves gradually decreases toward the axial front side of the cutting tap. The respective deburring thread grooves have groove bottom diameter reliefs by which the groove bottom dimeter gradually decreases from the front side toward the rear side of each deburring thread groove in the rotation direction of the cutting tap, the groove bottom diameter reliefs being set to be larger than effective diameter reliefs of the thread grooves.

Abstract: A cutting tap includes thread ridges, roots formed between the respective axially adjacent pairs of thread ridges, and a plurality of deburring thread grooves arranged at a constant pitch toward the axial front side of the cutting tap from the rearmost ones of the roots in which the deburring thread grooves are formed, and formed such that a groove bottom diameter of the deburring thread grooves gradually decreases toward the axial front side of the cutting tap. The respective deburring thread grooves have groove bottom diameter reliefs by which the groove bottom dimeter gradually decreases from the front side toward the rear side of each deburring thread groove in the rotation direction of the cutting tap, the groove bottom diameter reliefs being set to be larger than effective diameter reliefs of the thread grooves.

Abstract: A rotary cutting tool is provided which is less likely to cause chips to get stuck, and which can be manufactured at a low cost. The rotary cutting tool includes a body having a relief surface (6) and a rake face (7) which is connected to the relief surface (6). An oxide film (9) is formed on the rake face (7) by oxidizing the surface of the body, and a hard film (8) is formed on the relief surface (6) and the oxide film (9), The hard film (8) is made of a metal carbide, a metal nitride, a metal carbonitride, or a solid solution thereof.