(2) Determination of cutting parameters
　　 The cutting volume of Dongguan CNC processing plant includes spindle speed (cutting speed), back-cutting amount, and feed amount. For different processing methods, different cutting parameters need to be selected, and they should be programmed into the program list. The principle of reasonable selection of cutting parameters is that during rough machining, productivity is generally improved, but economy and processing costs should also be considered; during semi-finishing and finishing, cutting efficiency and cutting efficiency should be taken into account while ensuring the quality of machining. Economy and processing cost. The specific value should be determined according to the machine tool manual, cutting parameter manual, and combined with experience.
Seven, the determination of the tool setting point and the tool change point
　　Dongguan CNC machining factory should correctly select the position of "tool setting point" and "tool change point" when programming. The "tool setting point" is the starting point of the movement of the tool relative to the workpiece when machining parts on the CNC machine tool. Since the program segment is executed from this point, the tool setting point is also called "program starting point" or "tool starting point".
The selection principle of the knife point is:
2. It is easy to align on the machine tool and easy to check during processing;
3. The processing error caused is small.
　　 Dongguan CNC Processing Factory The tool setting point can be selected on the workpiece or on the outside of the workpiece (such as on the fixture or on the machine tool), but it must have a certain size relationship with the positioning datum of the part. In order to improve the machining accuracy, the tool setting point should be selected as far as possible on the design basis or process reference of the part, such as a workpiece positioned with a hole, the center of the hole can be selected as the tool setting point. The position of the tool is aligned with this hole, so that the "tool position point" and the "tool setting point" coincide. The common calibration method in the factory is to install the dial indicator on the machine tool spindle, and then rotate the machine tool spindle to make the "tool position point" consistent with the tool setting point. The better the consistency, the higher the accuracy of tool setting. The so-called "tool location point" refers to the tip of a turning tool and a boring tool; the tip of a drill; the center of the bottom surface of the end mill and end mill head, and the center of the ball end of a ball end mill.
　　 After the parts are installed, the workpiece coordinate system and the machine tool coordinate system have a certain size relationship. After the workpiece coordinate system is set, the coordinate value of the first block starting from the tool setting point; the coordinate value of the tool setting point in the machine tool coordinate system is (X0, Y0). When programming by absolute value, regardless of whether the tool setting point coincides with the workpiece origin, it is X2 and Y2; when programming by incremental value, when the tool setting point coincides with the workpiece origin, the coordinate value of the first block is X2 , Y2, when they do not overlap, it is (X1 + X2), Y1 + Y2). The tool setting point is both the start and end of the program. Therefore, the repeat accuracy of the tool setting point should be considered in batch production. The accuracy can be checked by the coordinate value (X0, Y0) of the tool setting point away from the machine origin.
　　 The so-called "machine origin" refers to a fixed limit point on the machine tool. For example, for a lathe, it refers to the intersection of the center of rotation of the spindle of the lathe and the end face of the head chuck. When the tool needs to be changed during processing, the tool change point should be specified. The so-called "tool change point" is the position of the tool holder when it is indexed and changed. This point can be a fixed point (such as a machining center machine tool, the position of the tool change manipulator is fixed), or an arbitrary point (such as a lathe). The tool change point should be located outside the workpiece or fixture, and the tool holder does not touch the workpiece or other parts when it is indexed. The set value can be determined by actual measurement method or calculation.
8. Determination of processing route
　　Dongguan CNC machining factory In CNC machining, the path of the tool position relative to the workpiece is called the machining route. When programming, the main principles for determining the processing route are as follows:
1) The processing route should ensure the accuracy and surface roughness of the processed parts, and the efficiency is high.
2) Make numerical calculation simple to reduce programming workload.
3) The processing route should be the shortest, which can reduce the program segment and the time of empty tool. To determine whether it is a single pass or multiple passes to complete the processing and whether to use down milling or up-cut milling in the milling process, determine whether it is one pass or multiple passes.
For CNC machine tools with point-position control, Dongguan CNC processing plants only require high positioning accuracy and the positioning process as fast as possible, while the movement path of the tool relative to the workpiece is irrelevant. Therefore, this type of machine tool should be arranged according to the shortest idle stroke. route. In addition, the axial movement size of the tool must be determined. The size is mainly determined by the hole depth of the machined part, but some auxiliary dimensions should also be considered, such as the lead-in distance and overrun amount of the tool.