Due to the complexity of precision CNC machining (such as different machine tools, different materials, different tools, different cutting methods, different parameter settings and so on), it determines that CNC machining must go through a relatively long period of time, then can reach a certain level. In the long-term actual production process, our engineers summary a manual, which is about some experience about CNC machining technology, procedures, selection of commonly used tool parameters, monitoring during machining and so on.
The division of numerical control processing procedures can generally be carried out according to the following methods.
1. Tool centralized sorting method
It is to divide the process according to the tool used, and use the same tool to machine all the parts that can be completed on the part. Use the second knife and the third knife to complete other parts they can complete. This can reduce the number of tool changes, reduce idle time, and reduce unnecessary positioning errors.
2. Order by processing parts
For parts with a lot of CNC machining content, the machining part can be divided into several parts according to its structural characteristics, such as inner shape, shape, curved surface or plane. Generally, the plane and positioning surface are processed first, and then the hole is processed. The simple geometric shape is processed first, and then the complex geometric shape is processed. The parts with lower precision are processed first, and then the parts with higher precision requirements are processed.
3. Sequential method of roughing and finishing
For parts that are prone to deformation in CNC machining, due to the deformation that may occur after rough machining, the shape needs to be corrected. Therefore, in general, all the processes that need to be roughed and finished must be separated.
When dividing the process, it must be flexibly controlled according to the structure and manufacturability of the parts, the function of the machine tool, the number of parts CNC machining content, the number of installations and the production organization of the unit. It is also recommended to adopt the principle of process concentration or the principle of process dispersion, which should be determined according to the actual situation, but must strive to be reasonable.
The arrangement of the processing sequence should be considered according to the structure of the part and the condition of the blank, as well as the needs of positioning and clamping. The important point is that the rigidity of the workpiece is not destroyed. The order should generally be carried out according to the following principles:
1. The processing of the previous process cannot affect the positioning and clamping of the next process, and the general machine tool processing processes should also be considered comprehensively.
2. The inner shape and cavity are processed first, and then the shape is processed by numerical control.
3. It is best to connect the processes of machining with the same positioning, clamping method or the same tool to reduce the number of repeated positioning, tool changes and the number of times of moving the platen.
4. For the multiple processes carried out in the same installation, the process should first be arranged with less rigid damage to the workpiece.
When determining the positioning reference and clamping plan, the following points should be paid attention to.
1. Strive to unify the design, craftsmanship, and programming calculation benchmarks.
2. Minimize the number of clamping times, as far as possible, to be able to CNC machine all the surfaces to be processed after one positioning.
3. Avoid using manual adjustment schemes that occupy the machine.
4. The fixture should be opened smoothly, and its positioning and clamping mechanism should not affect the cutting during processing such as collision. When encountering such a situation, it can be clamped by using a vise or adding a base plate to draw a screw.