CNC machining is the process of applying CNC machine tools to process parts. CNC machine tools are also known as machine tools that apply computer control, so the computers here are collectively referred to as numerical control systems. The instructions issued by the CNC system are mainly for effective control of the movement of the CNC machine tool and related auxiliary actions, while the instructions of the CNC system are compiled by the programmer according to the specified instruction format according to the material and processing requirements of the parts, combined with the characteristics of the machine tool. The various movements of the machine tool are executed in accordance with the instructions issued by the numerical control system, and the numerical control system must send various information to the machine tool according to the instructions prepared by the programmer. According to the program pre-programmed by the programmer, when the processing of the part is completed, the machine tool will automatically stop moving, under normal circumstances, if any kind of CNC machine tool is not entered into the program instruction, the CNC machine tool can not work normally.

Under normal circumstances, the CNC machining process mainly includes the following: select and determine the parts that need to be CNC machined; Process analysis of CNC machining of drawings of the parts to be machined; Process design for CNC machining of parts; mathematical processing of drawings of parts; Preparation and processing of program sheets; Production of control media according to the program list; Finally, the verification and modification of the program; Practical process analysis and on-site processing of first part trial processing; Archive documents related to CNC machining of parts. In the specific process analysis process, we must do the following work:

(1) Correctly mark the size of the part drawing. In the specific design process, since the CNC machining program is compiled with precise coordinate points, we must pay attention to the geometric elements of each figure and the interrelationship between the elements (such as tangency, intersection, parallel, etc.); It is necessary to fully clarify the conditions between various geometric elements, and avoid excess dimensions and closed dimensions that affect the process arrangement.

(2) Improve the machining accuracy of parts. Although the accuracy of CNC machine tools is much higher than that of traditional machine tools, for some special cases, such as too thin bottom plate and rib plate, due to the cutting tension generated during processing and the elastic retreat of the thin plate, the vibration of the cutting surface will increase, it is difficult to ensure the tolerance of the thickness and size of the thin plate, and also increase the roughness of the surface of the thin plate. Therefore, when we process thin plates with a large area and a thickness of less than 4 mm, we must pay full attention to this problem in the process.

(3) Keep the relevant dimensions of the arc in the outline of the part as uniform as possible. The diameter of the tool is often limited by the radius of the arc in the contour, if the height of the contour of the part is relatively low, and the radius of the transfer arc is also large, in this case we can use a larger diameter milling cutter to process, when machining the bottom plate surface, because the number of feeds will be reduced accordingly will improve the quality of surface processing, so the workmanship is better. Conversely, CNC milling has poor processability. Generally speaking, when R<0.2H (H is the maximum height of the contour surface to be machined), it can be judged that the workmanship of the part is not good.

(4) Ensure the principle of uniform benchmarks. Often, some parts need to be milled on one side and then re-milled on the other side, so we must remember to use a uniform fiducial positioning, and there should be suitable holes on the part as positioning reference holes. If there are no datum holes on the part, we can set the process holes specifically as positioning references. It is important to use a uniform geometry or size when designing the shape of the part, so as to reduce the number of tool changes and thus the length of the application.