CNC turning tools are generally classified into three categories: form tools, pointed tools, and circular arc tools. Form tools, also known as template tools, determine the contour shape of the workpiece entirely by the shape and size of the tool's cutting edge. Common form tools in CNC turning include small-radius circular arc tools, non-rectangular grooving tools, and threading tools. Form tools should be used sparingly or not at all in CNC machining. Pointed tools are characterized by straight cutting edges. The tip of these tools consists of straight primary and secondary cutting edges, such as 90° internal and external turning tools, left and right facing tools, grooving (parting) tools, and various external and internal turning tools with very small chamfers at the tip. The selection method for the geometric parameters (mainly geometric angles) of pointed tools is basically the same as in ordinary turning, but it should be comprehensively considered in conjunction with the characteristics of CNC machining (such as machining path, machining interference, etc.), and the strength of the tool tip itself should also be taken into account.
Secondly, there are circular arc tools. A circular arc turning tool is a turning tool characterized by a circular arc-shaped cutting edge with very small roundness or profile error. Each point of this tool's circular arc cutting edge is the tool tip; therefore, the tool tip is not on the arc itself, but at the center of the arc. Circular arc turning tools can be used for turning both internal and external surfaces, and are particularly suitable for turning various smooth, concave shapes. When selecting the radius of the circular arc of the turning tool, two points should be considered: the radius of the cutting edge should be less than or equal to the minimum radius of curvature on the concave profile of the workpiece to avoid machining defects. This radius should not be too small; otherwise, not only will manufacturing be difficult, but the tool may also be damaged due to weak tool tip strength or poor heat dissipation.