CNC Machining: What are The Similarities and Differences Between CNC Machining and Traditional Machining?

Compared with traditional machine tools, CNC machine tools have great advantages in technology and are the product of the development of modern technology. At present, CNC machining centers and CNC machine tools continue to use traditional processing technology in many aspects of processing technology, and integrate traditional processing technology with CNC machine tool processing characteristics, so that the advantages of CNC machine tool processing can be brought into play. However, it is unscientific to continue to use the traditional machine tool processing technology in this way. The technicians should evaluate the new processing technology according to the characteristics of CNC machining, so that the CNC machining technology can give full play to its advantages.

1. The CNC machining process is more complicated

When using the CNC machining process, it is necessary to fully consider the positioning datum, manufacturability and clamping method of the CNC machined parts, and also to formulate the process route, select the tool, consider the process parameters and cutting methods, etc. For these, it can be simplified in the CNC machining of traditional machine tools. Therefore, the CNC machining process is much more complicated in actual use, and there are many factors affected. In the process of use, it is necessary to carry out a scientific and reasonable analysis of the CNC programming, and the analysis must be comprehensive. The same CNC machining task can have different process schemes when using CNC machining. This is one of its main features and is unmatched by traditional CNC machining processes.

2. The choice of CNC machining tools

Since the methods and processes of CNC machining and traditional CNC machining are very different, the selection of tools is also very different. High-speed cutting is used in the CNC machining process, while high-speed cutting is used in traditional CNC machining, which has great advantages. High-speed cutting has greatly improved the quality and efficiency of CNC machining, and the cutting deformation is small. The machining cycle, therefore, should be appropriately increased for high-speed cutting in CNC machining. At present, dry cutting is used more. This method only needs to add a small amount of cutting fluid or no cutting fluid, but the tool must have ultra-high heat resistance. Compared with traditional CNC machining, CNC machining has higher requirements on tools. In addition, the status of tool manufacturers has changed, which has greatly changed the role and status of the tool industry: in the past, only the production and supply of tools was carried out alone, but now, not only the production of tools, but also the development of cutting processes and innovation, and manufacture corresponding supporting products and technologies; from the original tool supplier to an important partner for enterprise CNC machining and manufacturing to improve efficiency and quality.

3. Selection of clamping and fixtures

When performing CNC machining, there are two requirements for the clamp: first, the coordinate direction of the clamp and the machine tool should be fixed; second, the dimensional relationship between the machine tool coordinate system and the parts should be coordinated. When the CNC machining center selects the fixture, the position and installation requirements should be determined according to the reference hole and groove of the worktable, so that the dimensional relationship between the machine tool coordinate system and the parts can be ensured, which is related to the traditional CNC machining of machine tools. one of the differences.

When clamping, there are mainly two steps, namely clamping and positioning. When clamping a traditional machine tool, it is limited by the capacity of the machine tool, which increases the number of clamping times. When clamping a CNC machine tool, multiple surfaces can be processed at one time, thereby reducing the clamping error. Special fixtures are used in the clamping process to facilitate positioning and clamping, but the cost is very high. If the number of pieces to be processed is large, the cost allocated to the fixture cannot be ignored. When the fixture is designed and used, it should be paid attention to. CNC machining can be debugged through the instrument to meet the requirements of positioning standards. This process does not require special fixtures, as long as ordinary pressing elements can complete the clamping, which greatly reduces the cost.

4. Comparison of tool paths

When determining the tool path of an ordinary machine tool, it needs to be controlled and grasped by the staff themselves, while in CNC machining, the tool path has been determined when the project is compiled.
 

5. Comparison of CNC machining methods

CNC machine tools have a great feature. For some traditional machine tools, some processing methods need to be used carefully, and CNC machine tools make them usable. Cantilever boring in traditional machining and support boring formed by tailstock guidance have been replaced by turning boring in CNC machine tools and different forms of canned cycle methods. The empty tool method, filling method, dressing method and other processes used in traditional machining are replaced by various forms of back boring method, circular interpolation method and numerical control dressing method. At present, the new hard cutting, as a new CNC machining process, can not only improve the work efficiency, but also greatly reduce the cost input, which makes the traditional grinding process face new challenges. It is the development trend of modern manufacturing and processing. Compared with wet cutting, the green manufacturing process of dry cutting also has many advantages, but there are still shortcomings. However, by analyzing the influencing factors and characteristics of dry cutting, and finding compensatory measures, the advantages of this cutting method are still relatively large.

6. Comparison of cutting amount

In traditional CNC machining, the control and manipulation of the machine tool is completed by the staff with work experience, which is conservative in terms of safety and control ability, especially when operating on curved surfaces and curves, it is easy to appear Error, in order to reduce the scrap rate, the cutting amount is increased. When the CNC machine tool is processing, the control system controls the CNC machining action. No matter what kind of CNC machining is encountered, it can be well controlled, and the work of the tool on the working surface is flexible and automatic. Yes, there is no discontinuous phenomenon. During the CNC machining process, the program will set a reasonable use value for the amount of cutting, which greatly improves the CNC machining efficiency. Compared with traditional machine tool CNC machining, this has a great advantage.

At present, when high-speed machining is used for rough machining, the adopted scheme is a combination of high cutting speed, high feed rate and small cutting amount. In this process, the number of cuts needs to be increased, but a comprehensive comparison of CNC machining efficiency, durability, and system stiffness is still very valuable. In addition, in the process of high-speed machining, the speed is automatically optimized, the cutting speed is accelerated at the position where the cutting amount is small, and the cutting speed is increased at the position where the machining allowance is large, so that the time of CNC machining is shortened. The efficiency is improved, the damage rate of the tool is reduced, the durability is improved, and the processing quality is improved. After optimizing the F value, the cutting speed can be continuously changed according to the change of the allowance, which cannot be realized in the CNC machining of traditional machine tools.

7. Comparison of the degree of flexibility

Among the traditional machine tools, the flexibility of general-purpose machine tools is very good, but the efficiency of CNC machining is very low; while the special-purpose machine tools have higher efficiency of CNC machining, but there is no high applicable function of parts, and the flexibility is poor and the rigidity is large, which is difficult to adapt to. The continuous modification of products in the market makes the competitiveness weak. For CNC machine tools, as long as the program is changed, CNC machining of new parts can be performed, with good flexibility, automatic operation, high processing efficiency, and can well adapt to the fierce market competition.

8. Quality comparison

When CNC machining is used, the degree of automation is very high, and special attention should be paid to quality and safety. Before the process is put into production, it is necessary to test the processing technology, and only when all aspects of the production requirements can be met can it be put into actual production applications. In traditional CNC machining, the process file can be put into production after it is written, as a guide for the production line, and the above complicated process is not required.

To sum up, the basic guarantee of CNC machining technology is traditional machining technology, which is based on traditional technology to improve CNC machining technology. Although it has certain advanced technology, it still has its own shortcomings. Through the comparison of the two CNC machining processes, the advantages and disadvantages of the two machining processes are analyzed. It is necessary to correctly view the advantages and disadvantages of the two CNC machining processes, and arrange and use them reasonably, so as to improve the production efficiency of CNC machining.