HSS end mills are a type of milling tool with cutting tooth on the circumference and at the bottom and to shave metals, etc., by rotating. Their cutting tooth come in different shapes, and are capable of machining in various forms. The length, number and diameter of the cutting tooth vary; select the effective tooth according to the machining details of the cutting area. The material of the cutting tooth is high-speed steel, and it is suitable for machining relatively soft materials such as resin, aluminum, brass and general steel. Some of HSS end mills are applied surface coating to suit the materials of work material. Friction can be reduced by the use of cutting oil for longer tool lifespan. HSS end mills have toughness and are less likely to break, which make them cost-effective and suitable for assembly, parts machining of precision components, etc. HSS end mills that have worn out after a long period of use can be reused by polishing the cutting tooth.