Multi-flute ball end mill

A multi-flute ball end mill, comprising:

• a shank portion configured to rotate about a rotational axis;
• a cutting edge portion having a ball edge portion at a tip thereof;
• three or more ball edges formed on the ball edge portion of the cutting edge portion;
• three or more gashes formed between the respective ball edges;
• three or more peripheral cutting edges continuous with end portions of the ball edges on the shank portion side;
• and
• three or more flutes formed between the respective peripheral cutting edges continuously with the respective gashes,
• wherein a degree of curvature of each of the ball edges is 35% to 55%, the degree being a ratio of a length of a perpendicular line drawn from an apex of a convex curved line of each of the ball edges to a line segment connecting a rotation center point that is an intersection point between the rotational axis and the cutting edge portion with a terminal point of each of the ball edges on the shank portion side with respect to a length of the line segment,
• wherein each of the gashes includes four faces of a rake face of each of the ball edges, a gash wall face, a first gash face, and a second gash face, the four faces being continuous in a rotational direction of the multi-flute ball end mill, and
• wherein the second gash face is formed such that the closer the second gash face is to the rotation center point, the more inwardly the second gash face enters a second face of each of the ball edges continuous with a back side of each of the ball edges in the rotational direction.