The Skills List Of CNC Turning
The machining order of the parts: drilling first and then flat ends (this is to prevent shrinkage during drilling); roughing first, then finishing (this is to ensure the accuracy of the parts); first the machining tolerance is large and the final machining tolerance is small (This is to ensure that the surface with small tolerances is not scratched and prevents parts from deforming).
Choose a reasonable speed, feed rate and cutting depth according to the hardness of the material. My personal summary is as follows:
- 1. Choose high speed, high feed rate and large cutting depth for carbon steel materials. Such as: 1Gr11, choose S1600, F0.2, cutting depth 2mm;
- 2. Choose low speed, low feed rate and small cutting depth for cemented carbide. For example: GH4033, choose S800, F0.08, and cut depth 0.5mm;
- 3. Titanium alloy chooses low speed, high feed rate and small cutting depth. For example: Ti6, choose S400, F0.2, and cut depth 0.3mm.
Tool setting skills
The tool setting is divided into tool setting instrument tool setting and direct tool setting. Most lathes do not have a tool setting instrument, which means direct tool setting. The tool setting technique mentioned below is direct tool setting. First select the center of the right end 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 to the center of the right end of the part as the zero point; the tool touches the right end and enters Z0 to click to measure The measured value will be automatically recorded in the tool compensation value of the tool, which means that the Z axis tool setting is correct, the X tool setting is a trial cutting tool setting, and the outer circle of the tool turning part is less, and the measured outer circle value is measured ( If x is 20mm) input x20, click measure, the tool compensation value will automatically record the measured value, then the x axis is also right; this tool setting method, even if the machine is powered off, the call will not change after the call is restarted The tool value can be applied to the mass production of the same part for a long time, and the tool does not need to be re-adjusted when the lathe is closed.
After programming the parts, you need to carry out trial cutting and debugging after setting the tool. In order to prevent errors in the program and errors in the tool setting, which will cause collisions, we should first carry out the simulation of empty strokes, in the coordinate system of the machine tool. The tool is shifted to the right by 2 to 3 times the total length of the part; then the simulation process is started. After the simulation process is completed, the program and tool setting are confirmed. , And then find a full-time inspection and inspection. Only after the full-time inspection confirms that it is qualified, it means that the debugging is over.
Complete the machining of parts
After the trial cut of the first piece is completed, batch production is required, but the qualification of the first piece does not mean that the entire batch of parts will be qualified, because in the machining process, the tool will be worn due to the difference in the machining material. Soft, the tool wear is small, the machining material is hard, and the tool wear is fast, so during the machining process, it is necessary to diligently inspect, increase and decrease the tool compensation value in time to ensure the qualification of the parts.
In short, the basic principle of machining: first roughing, removing the excess material of the workpiece, and then finishing; vibration should be avoided during machining; to avoid thermal denaturation of the workpiece during machining, there are many reasons for the vibration, which may be overloaded Large; it may be the resonance between the machine tool and the workpiece, or it may be the lack of rigidity of the machine tool, or it may be caused by the passivation of the tool. We can reduce the vibration by the following methods; Whether the workpiece is clamped securely, increase the speed of the tool. The latter reduces the speed to reduce resonance. In addition, check whether it is necessary to replace the new tool.
In addition, in order to safely operate the CNC machine tool and prevent the machine tool from colliding, I have the following points:
It is often heard that if you do not touch the machine tool, you will not be able to learn the operation of the machine tool. This is a very wrong and harmful understanding. The collision of the machine tool is a great damage to the accuracy of the machine tool. , Which has a greater impact on machine tools with less rigidity.
Once the machine tool collides, the accuracy of the machine tool is fatal. Therefore, for high-precision CNC lathes, collisions must be absolutely eliminated. As long as the operator is careful and masters certain anti-collision methods, collisions can be completely prevented and avoided.
The main reasons for collisions are:
- First, the diameter and length of the tool are entered incorrectly;
- Second, the size of the workpiece and other related geometric dimensions are entered incorrectly, and the initial position of the workpiece is incorrect;
- Third, the workpiece coordinate system of the machine is set incorrectly Or, the zero point of the machine tool is reset during the machining process, and changes occur.
Most of the machine tool collisions occur during the rapid movement of the machine tool. The collisions at this time are also the most harmful and should be absolutely avoided. Therefore, the operator should pay special attention to the initial stage of the execution of the program and when the machine tool is changing the tool. At this time, once the program is edited incorrectly, and the diameter and length of the tool are entered incorrectly, then collision is likely to occur. At the end of the program, if the sequence of CNC axis retraction is wrong, then collision may also occur.
In order to avoid the above-mentioned collision, the operator must give full play to the functions of the five senses when operating the machine tool, and observe whether the machine tool has abnormal movements, sparks, noise and abnormal noise, vibration, and burning smell. If abnormal conditions are found, the program should be stopped immediately. After the problem of the standby bed is resolved, the machine tool can continue to work. In short, mastering the operation skills of CNC machine tools is a gradual process and cannot be achieved overnight.
It is based on mastering the basic operation of machine tools, basic machining knowledge and basic programming knowledge. The operation skills of CNC machine tools are not static. It is an organic combination that requires operators to give full play to their imagination and hands-on ability. It is an innovative labor.
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