2 CNC: CNC, the abbreviation of numerical control, refers to a method of controlling mechanical movement and machining process by using digital information. There are two versions of numerical control, NC (numerical control): representing the old version and the original numerical control technology. CNC (Computerized Numerical Control): Computer numerical control technology, the preferred abbreviation of numerical control. After 1970, computers gradually replaced hardware circuit components, which is called computer numerical control system. Usually, dedicated computers and interface circuits are used to control the actions of multiple numerical control devices. So now CNC generally refers to CNC (Computer Numerical Control).