The main contents of CNC programming include: analyzing the part pattern to determine the technological process, numerical calculation, writing processing program, proofreading program and first piece trial cutting.

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The specific steps of programming are described as follows:

1. Analyze the pattern and determine the process

When processing parts on CNC machine tools, the original data obtained by the craftsman is the part drawing. According to the part drawing, you can analyze the shape, dimensional accuracy, surface roughness, workpiece material, blank type and heat treatment status of the part, and then select the machine tool and tool, determine the positioning and clamping device, the processing method, the processing sequence and the cutting amount size. In the process of determining the process, the command function of the CNC machine tool used should be fully considered, and the efficiency of the machine tool should be fully utilized, so that the processing route is reasonable, the number of tool passes and the processing time are short. In addition, relevant process technical documents should be filled in, such as CNC machining process card, CNC tool card, tool path map, etc.

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2. Calculate the coordinate value of the tool path

According to the geometric dimensions of the part drawing and the programmed coordinate system, the movement track of the tool center is calculated to obtain all tool position data. General CNC systems have the functions of linear interpolation and arc interpolation. For contour processing of relatively simple planar parts (such as parts composed of straight lines and arcs), only the starting point, end point, and arc of geometric elements need to be calculated The coordinate value of the center of the circle (or the radius of the arc), the intersection or tangent point of two geometric elements. If the CNC system has no tool compensation function, the coordinate value of the motion path of the tool center must be calculated. For parts with complex shapes (such as parts composed of non-circular curves and curved surfaces), it is necessary to approximate the actual curve or curved surface with a straight line segment (or arc segment), and calculate the coordinate value of its node according to the required processing accuracy.

3. Writing parts processing program

According to the processing route, the tool motion trajectory data and the determined process parameters and auxiliary actions are calculated. The programmer can write the processing program of the part piece by piece according to the function instructions and block format specified by the numerical control system used. When writing, pay attention to: First, the standardization of program writing should be easy to express and communicate; second, on the basis of fully familiar with the performance and instructions of the CNC machine tool used, the skills of each instruction and the skills of program segment writing.