How To Learn CNC Machining Well

[Wu Feiyu]

Step 1: must be an excellent craftsman.
CNC machine tool integrates drilling, milling, boring, reaming, tapping and other processes. The technical literacy of process personnel is very high. Numerical control program is the process of using computer language to reflect the processing technology. Process is the basis of programming. If you don’t understand technology, you can never say you can program.

You should meet the following technical standards and requirements:
1. Be familiar with the structure and process characteristics of drilling, milling, boring, grinding and planing machines,
2. Familiar with the properties of processing materials.
3. Solid basic knowledge of tool theory, master the conventional cutting parameters of tools, etc.
4. Be familiar with the process specifications and guidelines of the enterprise, the general requirements that various processes can meet, and the process route of conventional parts. Reasonable material consumption and man hour quota, etc.
5. Collect a certain amount of data on cutting tools, machine tools and mechanical standards. In particular, be familiar with the tool system for NC machine tools.
6. Be familiar with the selection and maintenance of coolant.
7. Have a common sense understanding of relevant types of work. For example: casting, electrical processing, heat treatment, etc.
8. Good fixture foundation.
9. Understand the assembly and use requirements of machined parts.
10. It has a good foundation of measurement technology.

Step 2: be proficient in NC programming and the application of computer software.
I think this is relatively easy. There are only dozens of programming instructions, and all kinds of systems are similar. It usually takes 1-2 months to get familiar with it. The automatic programming software is a little more complex and needs to learn modeling. But for people with good CAD foundation, it is not difficult. In addition, if it is manual programming, the basis of analytical geometry is also better! Readers are most adaptable to the study of these knowledge. In practice, the standard of a good procedure is:
1. It is easy to understand and organized, and everyone can understand it.
2. The fewer instructions in a program segment, the better, for the purpose of simplicity, practicality and reliability. From the perspective of programming, I think the instructions are G00 and G01. Others are auxiliary instructions, which are set for convenient programming.
3. Easy to adjust. When the machining accuracy of parts needs to be fine tuned, it is best not to change the program. For example, if the tool is worn and needs to be adjusted, just change the length and radius in the tool offset table.

Step 3: be familiar with CNC machine tools. Proficient in the maintenance of CNC machine tools.
To be familiar with CNC machine tools, you should:
1. Familiar with CNC electrical components and control principle. Be able to say the names and functions of various components in the electric box, and understand the electrical schematic diagram. It can find out the alarm content according to the electrical alarm number.
2. Understand the structure and transmission principle of ball screw. Know which factors have a great impact on the accuracy of the machine tool.
3. Understand the structure of bearings at both ends of machine tool screw and its influence on machine tool accuracy.
4. Understand the lubrication system of the machine tool (bearing, spindle, each moving pair, gearbox, etc.) and the distribution of each lubrication point. The brand of machine tool lubricating oil and the normal consumption of oil every week or every month.
5. Understand the cooling system of machine tool: cutting (water, gas) cooling, spindle cooling, electric box cooling, etc
6. Understand the main transmission structure of the machine tool and the specific data characteristics between the speed and torque of each machine tool.
7. Understand the characteristics of machine tool guide rail pair: wire rail or slide rail, and how rigid (bearing capacity)?
8. Be able to eliminate common operation faults (such as exceeding the limit, error of tool number of tool magazine, etc.)
9. Proficient in various accuracy (static and dynamic) indexes and detection methods of machine tools.
10. Familiar with tool magazine mechanism and tool changing principle.

Step 4: cultivate good habits and adapt to the characteristics of NC machining.
The master suitable for NC machining should be modest, rigorous, calm, careful thinking, organized and independent.
1. The processing of some large parts includes not only many processing contents, but also the transformation of spatial three-dimensional coordinates. The calculation of machining path is very complex and difficult to determine. If the problems are not considered carefully and comprehensively, the calculation is inaccurate, and the program modification becomes more and more chaotic during debugging, the probability of error will be large. “Think before you act” is most appropriate here.
2. Part debugging is a process of cooperation among many people, including operators, inspectors, fixture designers, fixture assemblers, etc. When problems arise, we should consult them more, do more experiments, and avoid making arbitrary conclusions. Don’t blame employees who make mistakes too much, and have a “compassionate” attitude.
3. The work of NC machine tool is controlled by instructions. During debugging, you must be very clear about the running track of the machine tool before pressing the “start” button. Be rigorous and meticulous. Never let the machine tool move first. Once the program is wrong or the compensation parameters are incorrect, or the coordinate system is selected incorrectly. Parts will be scrapped if they are light, and safety accidents will occur if they are heavy. Those who have a bad temper, have no clue, and persist in teaching are not suitable for the operation of CNC machine tools.
4. In case of problems during debugging and processing, be calm and don’t panic and misoperate again. Better psychological quality.
5. When the parts fail to pass the commissioning for many times, the analysis shall be organized and the responsibility shall be given according to the basis. Some relevant departments will give various explanations for various reasons. At this time, you should have your own opinion and remember: it doesn’t matter to do a wrong thing, but you can’t choose the wrong way of doing things.

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