Machining refers to the formation of mechanical parts with a variety of mechanical processing equipment, mainly refers to the processing method without chemical reaction. Mechanical processing mainly includes manual processing and CNC processing: manual processing refers to the method of machinists manually operating milling machines, lathes, drilling machines, saws and other mechanical equipment to process various materials. Manual processing is suitable for small batch, simple parts production. CNC (CNC) refers to the use of CNC equipment for machinists to process, CNC machining in a continuous manner to process the workpiece, applicable to a large number of complex shapes of parts, including turning and milling centres, machining centres, thread cutting machine tools and so on.

CNC machining is currently the mainstream processing methods, we not only need to know the characteristics of CNC machining, but also know the steps of CNC machining, so as to better improve the processing efficiency. What are the steps of CNC machining?

1, analyse the processing drawings, determine the processing technology. Technical staff according to the processing drawings provided by the customer, analyse the shape of the parts, surface roughness, dimensional accuracy, type of blank, workpiece material, heat treatment conditions, and then select the machine tool and cutting tool, to determine the positioning and clamping device, machining method, machining sequence and cutting dosage. In the process of determining the machining process, to give full play to the efficiency of the machine tool, give full consideration to the command function of the CNC machine tool used, so that the machining route is reasonable, the number of times the tool travels is small, and the machining time is short.

2, a reasonable calculation of the coordinate value of the tool path. According to the geometric dimensions of the machined part and set the programming coordinate system, calculate the movement trajectory of the tool trajectory centre to get all the tool position data. General CNC systems have linear interpolation and circular interpolation functions. For the contouring of plane parts with simple shapes, it is only necessary to calculate the coordinate values of the start and end points of the geometric elements, the centre of the circular arc, and the intersection or tangent point of the two geometric elements. If the CNC does not have a tool compensation function, it is necessary to calculate the coordinate values of the tool centre's trajectory. For parts with complex shapes, it is necessary to approximate the actual curve or surface with straight line segments, and calculate the coordinate values of its nodes according to the required machining accuracy.

3, the preparation of parts of the CNC machining programme. According to the tool trajectory of the part, calculate the tool trajectory data, determine the process parameters and auxiliary action, the programmer can be based on the CNC system used to provide the functional instructions and the format of the programme segments, segment by segment to write the parts of the machining program. Preparation should pay attention to: 1, the norms of the program written to facilitate the expression and communication; 2, in full familiarity with the performance of the CNC machine tools used and instructions on the basis of mastering the use of each instruction and the preparation of program segments of the skills.

The above three are the steps of CNC machining, should be followed in the CNC machining process in order to higher energy machining.