CNC engraving machines are good at small tool finishing, with the ability of milling, grinding, drilling and high-speed tapping, and are widely used in many fields such as 3C industry, mold industry and medical industry. This article collects the common questions about CNC engraving processing.
1. What is the main difference between CNC engraving and CNC milling?
CNC engraving and CNC milling both use the principle of milling processing. The main difference is in the diameter of the tool used, where the common tool diameter range for CNC milling is 6-40 mm, while the tool diameter for CNC engraving processing is 0.2-3 mm.
2. CNC milling can only do rough machining, CNC engraving can only do finish machining?
Before answering this question, let's first understand the concept of process. Roughing process is a large amount of processing, finishing process is a small amount of processing, so some people habitually think of roughing as "heavy cutting", finishing as "light cutting". In fact, roughing, semi-finishing and finishing are process concepts, which represent different processing stages. Therefore, the accurate answer to this question is that CNC milling can do heavy cutting and light cutting, while CNC engraving can only do light cutting processing.
3. Can CNC engraving do rough machining of steel material?
To determine whether CNC engraving processing can process a certain material, mainly depends on how big the tool can be used. the tool used for CNC engraving processing determines its maximum removal capacity. If the shape of the mold allows the use of a tool with a diameter of more than 6 mm, it is highly recommended to use CNC milling first, and then remove the remaining material by engraving processing.
4. Can the addition of a speed increasing head to the spindle of a CNC machining center complete the engraving process?
It cannot be completed. This kind of product has appeared in the exhibition 2 years ago, but it cannot complete the engraving process. The main reason is that the design of CNC machining center considers its own tool range and the overall structure is not suitable for engraving processing. The main reason for this misconception is that they mistook the high-speed electric spindle as the only feature of the engraving machine. 5.
5. CNC engraving can use very small diameter tools, can it replace EDM?
No. It is not a substitute. Although engraving has reduced the range of tool diameters available for milling, small molds that were previously only available with EDM can now be machined with engraving. However, the length/diameter ratio of engraving tools is generally around 5:1. When using a small diameter tool, only very shallow cavities can be machined, whereas the EDM process has almost no cutting forces and can machine cavities as long as electrodes can be created.
6. What are the main factors that affect the engraving process?
Machining is a complex process and there are many factors affecting it, mainly the following: machine characteristics, tools, control system, material characteristics, machining process, auxiliary fixtures and surrounding environment.
7. What are the requirements of CNC engraving processing for control system?
CNC engraving processing is first of all milling processing, so the control system must have the control ability of milling processing. For small tool processing, at the same time, it must provide feed-forward function, path advance speed reduction to reduce the frequency of small tool breakage. At the same time, it is necessary to increase the tooling speed in the smoother path section, so as to improve the efficiency of engraving processing.
8. What characteristics of the material will affect the machining?
The main factors affecting the engraving performance of materials are material type, hardness and toughness. Material types include metallic materials and non-metallic materials. In general, the greater the hardness, the worse the processability, the greater the viscosity, the worse the processability. The more impurities, the worse the processability, and the greater the hardness of the particles within the material, the worse the processability. A general standard is: the higher the carbon content, the worse the processability, the higher the alloy content, the worse the processability, the higher the content of non-metallic elements, the better the processability (but generally the non-metallic content in the material is strictly controlled).
9. What materials are suitable for engraving processing?
Non-metallic materials suitable for engraving include Plexiglas, resin, wood, etc. Non-metallic materials not suitable for engraving include natural marble, glass, etc. Metal materials suitable for engraving include copper, aluminum, soft steel with hardness less than HRC40, and metal materials unsuitable for engraving include hardened steel, etc.
10. What is the influence of the tool itself on the processing and how?
The tool factors affecting the engraving processing include tool material, geometric parameters, and sharpening technology. The tool material used for engraving processing is cemented carbide material, which is a powder alloy, and the main performance indicator that determines the performance of the material is the average diameter of the powder. The smaller the diameter, the more wear-resistant the tool, the higher the durability of the tool, more knowledge of CNC programming concern WeChat public number (CNC programming teaching) to receive tutorials, the sharpness of the tool mainly affects the cutting force. The sharper the tool, the smaller the cutting force, the smoother the processing, the higher the surface quality, but the lower the durability of the tool. Therefore, different sharpness should be selected when machining different materials. When processing softer and sticky materials, the tool needs to be sharper, and when the hardness of the processed material is greater, the sharpness should be reduced to improve the durability of the tool. But it should not be too blunt, otherwise the cutting force will be too large and affect the processing. The key factor in the sharpening of the tool is the mesh of the finishing grinding wheel. Grinding wheel with high mesh number can grind more delicate cutting edge, which can effectively improve the durability of the tool. A wheel with a high mesh can produce a smoother rear face, which improves the surface quality of the cut.
11. What is the tool life formula?
Tool life is mainly the tool life during the machining of steel materials. The empirical formula is: (T is the tool life, CT is the life parameter, VC is the cutting line speed, f is the amount of tool eaten per red per revolution, P is the depth of tool eaten). Among them, the biggest influence on the tool life is the cutting line speed. In addition, tool radial runout, tool grinding quality, tool material and coating, coolant will also affect the tool durability.
12. How to protect the engraving machine tool equipment during the machining process?
1) Protect the tool setting instrument from excessive oil erosion.
2) Pay attention to the control of flying chips. Flying chips are very harmful to the machine tool, flying into the electric control cabinet will lead to short circuit, flying into the guide rail will reduce the life of the screw and guide rail, so when processing, the main part of the machine tool should be sealed well.
(3) When moving the lighting, do not pull the head, which can easily pull the head.
4）During the machining process, do not observe close to the cutting area so as not to hurt your eyes with flying chips. When the spindle motor is rotating, it is forbidden to do any operation on the table surface.
(5) When opening and closing the machine door, do not open and close it violently. In finishing, the impact vibration during the opening of the door will cause the machined surface to have tool lines.
(6) to give the spindle speed, after the start of machining, otherwise, due to the slow start of the spindle, resulting in not reaching the desired speed to start machining, so that the motor suffocated.
7) It is forbidden to place any tool or workpiece on the cross beam of the machine.
8) It is strictly forbidden to place magnetic tools such as magnetic suction cups and percentage meter holders on the electric control cabinet, otherwise it will damage the display.
13. What parameters need to be adjusted when the new tool is turning in the process of machining and the machining is very hard?
The reason for the hard machining is that the power and torque of the spindle can not bear the current cutting amount. A reasonable approach is to make a new path, reduce the depth of tool eating, grooving depth and trimming amount. If the overall machining time is less than 30 minutes, you can also improve the cutting state by adjusting the tool speed.
14. What is the role of cutting fluid?
Metal processing pay attention to adding cooling oil. The role of the cooling system is to take away the cutting heat and flying chips, and to lubricate the machining. The cooling fluid takes away the cutting heat, reduces the heat transferred to the tool and motor, and improves their service life. The flying chips are taken away to avoid secondary cutting. The lubricating effect reduces the cutting force and makes the machining more stable. In purple copper machining, the choice of oil-based cutting fluid can improve the surface quality.
15. What are the stages of tool wear?
Tool wear is divided into three stages: initial wear, normal wear, and rapid wear. In the initial wear stage tool wear is mainly due to the low temperature of the tool, and does not reach the optimal cutting temperature, at this time, the tool wear is mainly abrasive wear, such wear on the tool is relatively large, more CNC programming knowledge focus on WeChat public number (CNC programming teaching) to receive tutorials, it is easy to lead to tool chipping. This stage is a very dangerous stage, not handled well, may directly lead to tool chipping failure. When the tool spends the initial wear period, the cutting temperature of the tool reaches a certain value, which is the main wear is diffusion wear, and its role is mainly to cause local flaking. Therefore, the wear is relatively small and slow. When the wear reaches a certain level, the tool fails, and it enters the period of sharp wear.
16. Why and how do tools need to be ground?
We mentioned above that the tool is easy to break down in the initial wear stage, in order to avoid the phenomenon of breaking down, we must sharpen the tool. Make the cutting temperature of the tool gradually rise to a reasonable temperature. It is experimentally verified that the comparison is carried out using the same machining parameters. It can be seen that after sharpening, the tool life increases by more than two times.
The break-in method is to reduce the feed rate by half while maintaining a reasonable spindle speed, and the machining time is about 5 to 10 minutes. Take a small value when machining soft materials and a large value when machining hard metals.
17. How to determine severe tool wear?
The methods to determine severe tool wear are.
1) Listening to the machining sound and the appearance of a harsh screeching sound.
2) listening to the spindle sound, the spindle appears obvious holding rotation phenomenon.
(3) feel the vibration increase in processing, the machine tool spindle appears obvious vibration.
(4) look at the processing effect, the processed bottom surface tool pattern is sometimes good and sometimes bad (if the beginning of the stage so that the depth of the eating tool is too deep).
18. When should I change the tool?
We should change the tool at the time of about 2/3 of the tool life limit. For example, if the tool is severely worn at 60 minutes, the next machining should start tool change at 40 minutes, and make a habit of changing tools regularly.
19. Can a severely worn tool continue to be machined?
After the tool is severely worn, the cutting force can increase to 3 times of normal. And the cutting force has a great influence on the life of spindle electrode, the life of spindle motor and the force is inversely proportional to 3 times. For example, 10 minutes of machining with a 3 times increase in cutting force is equivalent to 10*33=270 minutes of spindle use under normal conditions.
20. How to determine the tool extension during roughing?
The shorter the tool extension, the better. However, in actual machining, if it is too short, the length of the tool has to be adjusted frequently, which affects the machining efficiency too much. Then how to control the tool extension length in the actual machining? The principle is like this: φ3 diameter toolpost can be processed normally by extending 5mm, φ4 diameter toolpost can be processed normally by extending 7mm, and φ6 diameter toolpost can be processed normally by extending 10mm. Try to go up to these values or less when putting on the tool. If the length of the upper tool is greater than the above values, try to control the depth of machining when the tool is worn, this is a little difficult to grasp, need more exercise.
21. How to deal with a broken tool when machining suddenly?
1) Stop machining and check the current serial number of machining.
2) Check the broken tool, whether there is a broken tool body, if so, take it out.
(3) analyze the reason for the broken tool, which is the most important, why the tool is broken? We have to analyze it from the above-mentioned various factors affecting the processing to analyze. But the reason for the broken tool is that the force on the tool has suddenly increased. Either the path problem, or the tool jitter is too large, or the material has a hard block, or the spindle motor speed is not correct.
4) After the analysis, replace the tool for machining. If there is no replacement path, to advance a serial number on the original serial number for machining, this time must pay attention to the feed rate will be down, one because the broken tool at the hardening is serious, and the second is to carry out tool grinding.
22. How to adjust the machining parameters when the rough machining situation is not good?
If the tool life is not guaranteed under the reasonable main axis speed, when adjusting the parameters, adjust the draft depth first, then adjust the feed speed, and then adjust the lateral feed. (Note: Adjusting the depth of tooling is also limited, if the depth of tooling is too small, so too much delamination, although the theoretical cutting efficiency is high, but the actual processing efficiency is affected by some other factors, resulting in processing efficiency is too low, it should be replaced by a smaller tool for processing, but the processing efficiency is higher. Generally speaking, the minimum depth of tool eating should not be less than 0.1mm.