What should be paid attention to in CNC machining?

1. How to program

  (1) The machining sequence of parts should be drilled first and then flat end (this is to prevent material shrinkage during drilling); first rough turning, then fine turning (this is to ensure the accuracy of the parts); first machining with large tolerances and small final machining tolerances (This is to ensure that the surface of the small tolerance dimension is not scratched and prevent the deformation of the part).

  (2) Select a reasonable speed, feed and depth of cut according to the hardness of the material.

  1. High speed, high feed rate and large depth of cut are selected for carbon steel materials. Such as: 1Gr11, select S1600, F0.2, 2mm depth of cut;

  2. Cemented carbide chooses low speed, low feed and small depth of cut. Such as: GH4033, select S800, F0.08, depth of cut 0.5mm;

  3. Select low speed, high feed rate and small depth of cut for titanium alloys. Such as: Ti6, select S400, F0.2, depth of cut 0.3mm. Take me processing a part as an example: the material is K414, which is a very hard material. After many tests, the final selection is S360, F0.1, and the depth of cut is 0.2, and only qualified parts can be processed.

2. How to preset tools？

  First select the center of the right end face of the part as the tool setting point, and set it as the zero point. After the machine tool returns to the origin, each tool that needs to be used is set at the zero point of the center of the right end face of the part; when the tool touches the right end face, enter Z0 and click to measure, The measured value will be automatically recorded in the tool offset value of the tool, which means that the Z-axis tool setting is good, and the X tool setting is a trial cutting tool setting. If x is 20mm) input x20, click to measure, the tool compensation value will automatically record the measured value, then the x-axis is also correct; this tool setting method, even if the machine tool is powered off, it will not change after the power is restarted. The tool value is suitable for mass production of the same part for a long time, during which the lathe does not need to be re-calibrated.

3. How to debug？

  After the parts are programmed, they need to be tested and debugged after the tool is set. In order to prevent errors in the program and mistakes in tool setting, resulting in collision accidents, we should first perform idle travel simulation processing and face them in the coordinate system of the machine tool. The tool is moved to the right by 2-3 times the total length of the part; then start the simulation processing, after the simulation processing is completed, confirm that the program and tool setting are correct, and then start processing the part. After the first part is processed, first self-check to confirm that it is qualified , and then find a full-time inspection and inspection. After the full-time inspection is confirmed, it means that the debugging is over.

4.What should do when mass production?

After the first piece of trial cutting is completed, the parts will be mass-produced, but the qualification of the first piece does not mean that the whole batch of parts will be qualified, because during the processing, the tool will be worn due to the difference of the processing material, and the processing material Soft, the tool wear is small, the processing material is hard, the tool wear is fast, so in the process of processing, it is necessary to check frequently, increase and decrease the tool compensation value in time to ensure the qualified parts.

  In short, the basic principles of machining: first rough machining, remove excess material from the workpiece, and then finish machining; avoid vibration during machining; avoid thermal denaturation of workpiece during machining. There are many reasons for vibration, which may be overloaded. Large; it may be the resonance between the machine tool and the workpiece, or the rigidity of the machine tool may be insufficient, or it may be caused by the passivation of the tool. We can reduce the vibration by the following methods; reduce the lateral feed and machining depth, check Whether the workpiece clamping is reliable, increase the speed of the tool and reduce the speed to reduce the resonance. In addition, check whether it is necessary to replace a new tool.