CNC machining programming: refers to the process of automatically generating CNC machining programs with the support of the computer and the corresponding computer software system. It gives full play to the computer's fast computing and storage function.

1.The Principle Of Coarse First And Then Fine

The machining sequence of each surface is carried out in the order of roughing, semi-finishing, finishing and finishing, with the aim of gradually improving the precision and surface quality of the machined surface of the part. If the parts of all the surfaces are processed by CNC machine tools, work by row - generally according to the roughing, semi-finishing, finishing order, that is, after the completion of all the rough machining and then semi-finishing and finishing. Roughing when the majority of the machining margin can be quickly removed, and then finishing each surface in turn, so as to improve production efficiency, but also to ensure the machining accuracy of the parts and surface roughness. This method is suitable for machining surfaces with high requirements for positional accuracy. This method is suitable for machining surfaces with high requirements for positional accuracy. This is not absolute, such as for - some dimensional accuracy requirements of the processing surface, taking into account the rigidity of the part, shape and size accuracy requirements, can also be considered Consider these machining surfaces are completed in the order of roughing, semi-finishing, finishing. For the high accuracy requirements of the processing surface, in the roughing and finishing process, the parts are best set aside for a period of time After rough machining, the surface stress of the parts is completely released, reducing the degree of stress deformation on the surface of the parts, which is conducive to improving the machining accuracy of the parts.

2.Face First, Then Hole Principle

For the box class, bracket class, body class and other parts, the plane profile size is larger, plane positioning is more stable and reliable, so the plane should be machined first, and then the hole. In this way, not only to make the subsequent Machining has a stable and reliable plane as a positioning reference surface, and in the flat surface processing holes, processing becomes easier, but also conducive to improving the accuracy of hole processing. Usually, the part can be divided into processes according to the processing parts, generally first processing simple geometry, after processing complex geometry; first processing of lower precision parts, after processing higher precision parts; first processing plane, After processing holes.

3. Base Surface First Processing Principle

At the beginning of processing, always used as a finishing reference surface processing out, because the positioning reference surface is accurate, the clamping error is small, so the processing of any part, always first to the positioning roughing and semi-finishing of the positioning reference surface, if necessary, but also finishing, for example, shaft parts are always roughing and semi-finishing of the positioning reference surface, and then finish machining. For example, shaft Parts are always processed first center hole, and then the center hole surface and positioning hole for the finishing reference processing hole system and other surfaces. If there is more than one precision datum surface, it should be in accordance with the sequence of datum conversion and gradually To improve the processing accuracy of the principle to arrange the processing of the datum surface.

4. Internal First, Then External Principle

For precision sleeve, the coaxiality requirement between outer circle and hole is high, and the principle of hole first and then outer circle is generally adopted, that is, the outer circle is used as the positioning reference to process the hole first, and then the hole with higher accuracy is used as the positioning reference to process the outer circle. This can ensure the high coaxiality requirement between the outer circle and the hole, and the fixture structure is also very simple.

5. Principles For Reducing The Number Of Tool Changes

In CNC machining, the machining sequence should be arranged as much as possible according to the order in which the tool enters the machining position.