The tools can be divided into five types according to the surface of the workpiece: the tools for machining various outer surfaces include turning tools, planing knives, milling cutters, outer surface broaches and boring tools; hole machining tools include drill bits, reaming drills, boring tools , reamer and inner surface broach, etc.; thread processing tools include taps, dies, automatic opening and closing thread cutting heads, thread turning tools and thread milling cutters; gear processing tools include hobs, gear shaping knives, shaving knives, cones Gears and broaches, etc.; cutting tools include insert circular saw blades, band saws, hacksaws, cutting tools and saw blades, and so on. In addition, there are combination tools. According to the cutting motion mode and the corresponding blade shape, the tools can be divided into three categories: general-purpose tools such as turning tools, planing knives, milling cutters (excluding forming turning tools, forming planing tools and forming milling cutters), boring tools, drill bits, and expansion. Hole drills, reamers, saws, etc.; cutting tools such as cutting edges have the same or nearly the same shape as the workpiece to be machined, such as forming turning tools, forming planers, forming cutters, broaches, cone reamers and various Threading tools, etc.; special tools for machining special workpieces such as gears, splines, etc. Such as pinion cutters, shaving cutters, bevel gear planers and bevel gear milling cutters, etc.