After selecting the cnc processing method and dividing the process, the main content of the process route is to rationally arrange the order of these processing methods and processes. The cnc processing procedures of parts usually include cutting procedures, heat treatment procedures and auxiliary procedures (including surface treatment, cleaning and inspection, etc.). The sequence of these processes directly affects the processing quality, production efficiency and processing cost of the parts. Therefore, when designing the cnc processing process route, the sequence of cutting, heat treatment and auxiliary processes should be reasonably arranged, and the connection problem between the processes should be solved.

Arrangement of cnc processing procedures:

(1) Rough first and then finish. For example, follow the order of rough turning-semi-finish turning-finishing turning to gradually improve the machining accuracy. Rough turning will cut off most of the machining allowance on the surface of the workpiece (the part shown in the cool dotted line as shown in Figure 2-4) in a short time. This improves the metal removal rate on the one hand, and on the other hand satisfies the uniformity requirements of the precision turning. If the uniformity of the margin left after rough turning cannot meet the requirements of finishing, semi-finishing turning should be arranged to prepare for finishing. The precision turning must ensure the machining accuracy, and the contour of the part is cut out according to the size of the drawing.

(2) Near first and farther away. Under normal circumstances, the modern part away from the tool setting point is processed first, and the part away from the tool setting point is processed later in order to shorten the tool moving distance and reduce the idle travel time. For turning, it is beneficial to maintain the rigidity of the blank or semi-finished product and improve its cutting conditions.

(3) The principle of internal and external intersection. For parts that have both internal surfaces (inner cavity) and external surfaces that need to be processed, when arranging the processing sequence, the internal and external surfaces should be roughed first, and then the internal and external surfaces should be finished. Do not process a part of the surface (outer surface or inner surface) of the part before processing other surfaces (inner surface or outer surface).

(4) The principle of base surface first should give priority to processing the surface used as a precision datum. This is because the more accurate the surface of the positioning reference, the smaller the clamping error. For example, when machining shaft parts, the center hole is usually processed first, and then the outer surface and the end surface are processed on the center hole as a fine reference.

(5) The principle of first, first and then second. The main working surface and assembly base surface of the part should be processed first, so as to detect possible modern defects on the main surface of the blank as soon as possible. The secondary surface can be interspersed and carried out after the main processing surface has been processed to a certain degree and before the final finishing.

(6) The principle of face first, hole second. The box body and bracket parts have a larger plane outline size. Generally, the plane is processed first, and then the holes and other sizes are processed. Arranging the processing sequence in this way, on the one hand, it is stable and reliable with the machined plane positioning; on the other hand, it is easy to machine holes on the machined plane and can improve the machining accuracy of the holes, especially when the axis of the hole is not easy when drilling. Partial.