CNC Lathe Operation Skills

Programming Skills:

1. First, consider the processing order of parts. Drill first and then flatten (this is to prevent shrinkage during drilling); Rough turning first, then fine turning (this is to ensure the accuracy of parts); Process large tolerances first and then small tolerances last (this is to ensure that the surface of small tolerance dimensions is not scratched and prevent parts from deformation).

2. Then according to the hardness of the material, we choose a reasonable speed, feed rate and cutting depth. Carbon steel materials choose high speed, high feed rate and large cutting depth. For example: 1Gr11, choose S1600, F0.2, cutting depth 2mm; cemented carbide chooses low speed, low feed rate and small cutting depth. For example: GH4033, choose S800, F0.08, cutting depth 0.5mm; titanium alloy chooses low speed, high feed rate and small cutting depth. For example: Ti6, choose S400, F0.2, cutting depth 0.3mm. Take the processing of a certain part as an example: the material is K414, which is a special hard material. After many tests, S360, F0.1, and cutting depth of 0.2 were finally selected to process qualified parts.

Tool Setting Skills:

Tool setting is divided into tool setting instrument tool setting and direct tool setting. Some lathes in my previous work did not have tool setting instruments, so they were directly set. The tool setting skills mentioned below are direct tool setting. 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 with the center of the right end face of the part as the zero point; when the tool touches the right end face, enter Z0 and click Measure, and the tool compensation value of the tool will automatically record the measured value, which means that the Z-axis tool setting is done. The X-axis tool setting is a trial cutting tool setting. Use the tool to turn the outer circle of the part less. Measure the outer circle value (such as x is 20mm) and enter x20. Click Measure, and the tool compensation value will automatically record the measured value. At this time, the X-axis is also well set.

This tool setting method will not change the tool setting value after the machine tool is powered off and restarted. It can be used for mass production of the same part for a long time. There is no need to re-set the tool even if the lathe is turned off during the process.

Debugging skills.

Complete the Processing of Parts:

After the first trial cutting of the parts is completed, they will be produced in batches, but the qualification of the first piece does not mean that the whole batch of parts will be qualified, because in the process of processing, the tool will be worn due to the different processing materials. The processing material is soft, the tool wear is small, and the processing material is hard, the tool wear is fast. Therefore, during the processing, it is necessary to measure and check frequently, increase and decrease the tool compensation value in time to ensure the qualification of the parts.[Take the previously processed parts as an example: the processing material is K414, the total processing length is 180mm, because the material is very hard, the tool wears very quickly during processing, from the starting point to the end point, there will be a 10~20mm slight deviation due to tool wear, so it is necessary to add a 10~20mm slight deviation in the program manually, so as to ensure the qualification of the parts. 

In short, the basic principle of processing: first rough processing, remove the excess material of the workpiece, and then fine processing; vibration should be avoided during processing; avoid thermal denaturation of the workpiece during processing. There are many reasons for the vibration, which may be excessive load; it may be the resonance of 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. The following methods can be used to reduce vibration; reduce the lateral feed rate and processing depth, check whether the workpiece is clamped firmly, increase the speed of the tool or reduce the speed to reduce resonance, and check whether it is necessary to replace the new tool.

Prevent Machine Tool Collision:

Machine tool collision is a great damage to the accuracy of the machine tool, and the impact on different types of machine tools is different. Generally speaking, it has a greater impact on machine tools with weak rigidity. 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 incorrectly positioned;

Third, the workpiece coordinate system of the machine tool is set incorrectly, or the machine tool zero point is reset during the processing process, resulting in changes. Machine tool collisions mostly occur during the rapid movement of the machine tool. The harm of collisions at this time is also the greatest and should be absolutely avoided. Therefore, the operator should pay special attention to the initial stage of the machine tool in the execution of the program and when the machine tool is changing the tool. At this time, once the program is edited incorrectly, the diameter and length of the tool are entered incorrectly, then it is easy to collide. At the end of the program, the sequence of the tool retraction action of the CNC axis is wrong, then a collision may also occur.

In order to avoid the above collisions, the operator should give full play to the functions of the five senses when operating the machine tool. Observe whether the machine tool has abnormal movements, sparks, noise and abnormal sounds, vibrations, and burning smells. If an abnormal situation is found, the program should be stopped immediately, and the machine tool can continue to work after the machine tool problem is solved. 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 mechanical processing knowledge and basic programming knowledge. The operation skills of CNC machine tools are not static. It requires the operator to give full play to the organic combination of imagination and hands-on ability, and is innovative labor.