The selection of cutting tools is one of the important contents in CNC machining technology, which not only affects the machining efficiency of the machine tool, but also directly affects the machining quality of the parts. Due to the fact that the spindle speed and range of CNC machine tools are much higher than ordinary machine tools, and the spindle output power is larger, compared with traditional machining methods, higher requirements are put forward for CNC machining tools, including high accuracy, strength, rigidity, durability, size stability, and easy installation and adjustment. This requires a reasonable structure of the cutting tool, standardization of geometric parameters, and serialization. CNC cutting tools are one of the prerequisites for improving machining efficiency, and their selection depends on the geometric shape of the machined parts, material status, fixture and the rigidity of the tool used in the machine tool. The following aspects should be considered:

(1) Select the cutting tool based on the cutting performance of the part material. For turning or milling high-strength steel, titanium alloy, and stainless steel parts, it is recommended to choose indexable hard alloy cutting tools with good wear resistance.

(2) Select cutting tools based on the machining stage of the parts. In the rough machining stage, the removal of excess material is the main focus, and tools with good rigidity and low accuracy should be selected. In the semi precision and precision machining stages, tools with high durability and accuracy should be selected to ensure the machining accuracy and product quality of the parts. The precision of the tools used in the rough machining stage is the lowest, while the precision of the tools used in the precision machining stage is the highest. If the same tool is selected for rough and precision machining, it is recommended to use the tool that has been eliminated from precision machining during rough machining, because the wear of the eliminated tool from precision machining is mostly slight wear on the edge, and the coating is worn and polished. Continuing to use it will affect the machining quality of precision machining, but the impact on rough machining is relatively small.

(3) Select cutting tools and geometric parameters based on the characteristics of the processing area. When the structure of the parts allows, cutting tools with large diameters and small aspect ratios should be selected; The end edge of the over center milling cutter for cutting thin-walled and ultra-thin wall parts should have sufficient centripetal angle to reduce the cutting force on the tool and cutting area. When processing parts made of softer materials such as aluminum and copper, a slightly larger rake angle end mill should be selected, and the number of teeth should not exceed 4.

When selecting a tool, it is important to ensure that the size of the tool matches the surface size of the workpiece being processed. In production, the peripheral contour of flat parts is often processed using end mills; When milling flat surfaces, a hard alloy blade milling cutter should be selected; When processing protrusions and grooves, choose high-speed steel end mills; When processing rough surfaces or rough holes, a corn milling cutter with a hard alloy blade can be selected; Ball end milling cutters, circular milling cutters, conical milling cutters, and disc milling cutters are commonly used for the processing of some three-dimensional surfaces and variable angle profiles.

When machining free-form surfaces, due to the zero cutting speed at the end of the ball end tool, in order to ensure machining accuracy, the cutting line spacing is generally very small. Therefore, the ball end milling cutter is suitable for precision machining of surfaces. And the end milling cutter is far superior to the ball end milling cutter in both surface processing quality and processing efficiency. Therefore, when rough machining and semi precision machining of curved surfaces, it is recommended to choose the end milling cutter as much as possible while ensuring that the parts are not cut. In addition, the durability and accuracy of cutting tools are closely related to tool prices. It must be noted that in most cases, selecting a good tool may increase tool costs, but the resulting improvement in machining quality and efficiency can greatly reduce the overall machining cost.

On the machining center, all cutting tools are pre installed in the tool library and corresponding tool changing actions are carried out through the selection and tool changing instructions of the CNC program. It is necessary to select corresponding standard tool holders that are suitable for the specifications of the machine tool system, so that CNC machining tools can be quickly and accurately installed on the machine tool spindle or returned to the tool library. Programmers should be able to understand the structural dimensions, adjustment methods, and adjustment range of the tool holder used in the machine tool, in order to ensure that the radial and axial dimensions of the tool are determined and the arrangement order of the tool is reasonably arranged during programming.