End mills are widely used in various machining. Especially, ball end mills are in the widest use to create a variety of curved surfaces. In recent years, high speed milling has been gradually utilized in the light of machining efficiency. It is due to the development of machine tools with high speed and high accuracy, together with the advance of CNC. However, tool wear and breakage are becoming conspicuous with high speed milling. Thus, demands for tools suitable for high speed milling are rapidly increasing. In this study, four kinds of ball end mills were designed and fabricated by means of a tool grinding CAD/CAM system developed by ourselves. As a result, it is found that ball end mills with negative helix angle and negative rake angle are superior to the others from high speed cutting experiments.
