The work out method of CNC Machining program basically has two kinds: Program of manual work out and program of automatic work out. (1) manual process designing points to manual process designing to basically work by what will complete each phase in numerical control process designing artificially. If pursue,next place are shown. General not quite complex to geometrical appearance part, wants machine program is not long, calculation is simpler, compare with manual process designing appropriate. The characteristic of manual process designing: Between cost take time longer, appear easily mistake, cannot be competent the process designing of complex form spare parts. According to foreign data statistic, when using manual process designing, of a paragraph of program write what time runs the actual time of treatment on the machine tool with its to compare, it is on average about 30: 1, and because machine program work out is difficult,numerical control machine tool cannot have 20%~30% in the reason of actuate is, process designing time is longer. (2) the computer is automatic process designing is automatic process designing is to point to in process designing process, besides the analysis part drawing appearance is mixed outside making craft honest brief of a case undertake artificially, the others job all is assisted by the computer finish. Use the computer when automatic process designing, mathematical processing, writing the work such as program, checking program is finished automatically by the computer, as a result of the computer but automatic scale gives contrail of motion of cutting tool center, make process designing personnel can check an order in time correct, when need can revise in time, in order to obtain right order. As a result of the computer automatic process designing replaced to program personnel to finish trival numeric computation, can improve process designing efficiency a few times it is consummate hundredfold, because this solved the process designing difficult problem of a lot of complex parts with manual inextricability process designing. Consequently, the characteristic of automatic process designing depends on process designing work efficiency tall, can solve the process designing difficult problem of complex form spare parts. What the basis inputs means is different, can be cent of automatic process designing graphical numerical control numerical control of automatic process designing, language is automatic process designing and speech numerical control are automatic process designing. Graphical numerical control is automatic process designing is to show the graphical information the spare parts inputs the computer directly, pass the processing of software of automatic process designing, receive CNC Machining order. Current, graphical numerical control is automatic process designing is to use means of most extensive automatic process designing. After automatic process designing points to language numerical control to reach parameter of requirement of the geometrical dimension that machines a spare parts, craft, cutting auxiliary information to wait to write source program with numerical control language, in inputting the computer, handle further by the computer again get spare parts machine program. Speech numerical control is automatic process designing is to use speech recognition implement, the treatment that gives out process designing personnel dictates voice change is machine program. CNC Milling