By jett NG | 08 June 2021 | 0 Comments

What are the main differences between CNC engraving and CNC milling?|www.easoar-soon.com

What should we do after the appearance of lines in CNC machining?|www.easoar-soon.com

 

CNC milling machine is also known as CNC milling machine. In English, it means a milling machine controlled by digital signals using an electronic meter. CNC machining is a necessary device for machining tool die, it can more accurately improve the quality and quality of tool die. Minghong knife precision die is specialized in the production of custom machining knife die. Then how to analyze the grain after processing?

CNC after the grain is generally too low speed, tool wear, feed is too high, the knife is too large, there may be no clamping workpiece vibration. CNC processing products in that part of the knife grain, if there is rough and finishing, to distinguish which is caused by a knife, find the reason. Is the cutting fluid aligned with the tool? Does the cutting fluid concentration meet the requirements?

Cutter mold CNC processing

Whether the cutting amount is too large, whether the tool is seriously worn, whether the tool machining path is reasonable: whether the speed and feed are appropriate, sometimes the appropriate increase in speed can improve the surface finish of the workpiece. Whether the fixture pressing plate is reasonable: whether the pressing plate compacts the workpiece. If there is no compressing, the knife pattern will be generated during processing. Whether the spindle tool handle and taper hole are padded with aluminum chips, whether the jacket is padded with debris when the tool is installed, use the dial gauge to hit the tool, observe whether the yaw is within the standard range? According to these problems to the appropriate medicine will be more efficient.

CNC milling machine

112. The 21 questions of CNC finishing machine processing, the main difference between CNC engraving and CNC milling?

1. What are the main differences between CNC engraving and CNC milling?

Both CNC engraving and CNC milling are based on the principle of milling. The main difference is in the diameter of the tool used, in which CNC milling commonly used tool diameter range is 6-40 mm, while CNC engraving tool diameter is 0.2-3 mm.

2. CNC milling can only do rough machining, CNC engraving can only do fine machining?

To answer this question, let's first take a look at the concept of process. Rough machining process of large processing quantity, finishing processing quantity is small, so some people will be used to rough machining is considered to be "heavy cutting", will be considered to be "light cutting". In fact, roughing, semi-finishing and finishing are process concepts, which represent different stages of processing. So, the correct answer to this question is that CNC milling can do either heavy or light cutting, while CNC engraving can only do light cutting.

3 CNC engraving can do rough machining of steel materials?
Determining whether CNC engraving processing can process a material, mainly depends on how big the tool can be used. The tool used for CNC engraving determines its maximum cutting capacity. If the die shape allows the use of tools larger than 6 mm in diameter, it is highly recommended to use CNC milling first, followed by engraving to remove the remaining material.

4 CNC machining center spindle to add a growth head can complete the engraving processing?

Can't finish. This product was shown at the exhibition two years ago, but could not be finished carving. The main reason is that the design of CNC machining center considers its own tool range, the overall structure is not suitable for engraving processing. The main reason for this misconception is that they mistook the high speed motorized spindle as the only feature of the engraving machine.

5 CNC engraving can be used in small diameter tools, it can replace the EDM?

There is no substitute. Although engraving reduces the tool diameter range for milling, small molds that previously could only be EDM can now be achieved by engraving. However, the length/diameter ratio of the carving tool is generally about 5:1. When a small diameter tool is used, only a very shallow cavity can be machined, whereas an EDM process has little cutting force, and the cavity can be machined as long as an electrode can be created.

6. What are the main factors affecting engraving processing?

Mechanical processing is a more complex process, the influence of its factors are more, mainly there are the following points: machine characteristics, cutting tools, control system, material characteristics, processing technology, auxiliary fixture and surrounding environment.

7. What are the requirements of CNC engraving control system?

CNC engraving processing is the first milling processing, so the control system must have the control ability of milling. For small tool machining, the feedforward function must be provided at the same time to reduce the speed of the path in advance to reduce the frequency of small tool breaking. At the same time, it is necessary to improve the cutting speed in the smooth path section, so as to improve the efficiency of engraving.

8. What properties of the material will affect the processing?

The main factors affecting the engraving performance of materials are material type, hardness and toughness. Material categories include metallic materials and nonmetallic materials. In general, the greater the hardness, the worse the workability, the greater the viscosity, the worse the workability. The more impurities, the worse the workability, the greater the hardness of the particles inside the material, the worse the workability. A general standard is: the higher the carbon content, the worse the workability, the higher the alloy content, the worse the workability, the higher the content of non-metallic elements, the better the workability (but the general material of the non-metallic content is strictly controlled).

9. Which materials are suitable for engraving?

Non-metallic materials suitable for carving include plexiglass, resin, wood, etc., and non-metallic materials not suitable for carving include natural marble, glass, etc. Metal materials suitable for engraving include copper, aluminum, soft steel with hardness less than HRC40, and metal materials not suitable for engraving include hardened steel, etc.

10. What is the impact of the tool itself on the processing, and how?

The factors affecting the engraving process include the cutting tool material, geometric parameters, grinding technology.

The tool material used in carving processing is cemented carbide material, which is a powder alloy. The main performance index to determine the material performance is the average diameter of the powder. The smaller the diameter, the more wear-resistant the tool, and the higher the tool durability.

The sharpness of the tool mainly affects the cutting force. The sharper the tool, the less cutting force, the smoother the machining, the higher the surface quality, but the lower the tool durability. Therefore, different sharpness should be chosen when processing different materials. Processing soft and sticky materials, the need for a sharp tool, when the processing material hardness is large, to reduce sharpness, improve the durability of the tool. But not too blunt, otherwise the cutting force will be too large, affecting the processing.

The key factor of tool grinding is the number of mesh of finishing grinding wheel. Grinding wheels with higher mesh can produce finer cutting edges, which can effectively improve the tool's durability. Higher mesh grinding wheel can produce a smoother back surface and improve the quality of cutting surface.11. In the process of processing, how to protect the engraving machine equipment?

1) Protect the tool setting instrument, do not let it be too much eroded by oil.

2) we should pay attention to the control of flying chips, flying chips on the machine tool is very harmful, fly to the electric control cabinet will lead to short circuit, fly to the guide rail will reduce the life of the lead screw, guide rail, so in processing, to the main part of the machine tool sealed.

3) when moving the lamp, do not pull the lamp holder, it is easy to pull the lamp holder.

4) In the processing process, do not close to the cutting area for observation, in order to avoid flying chip injury to the eyes. When the spindle motor is rotating, do not carry out any operation on the table surface.

5) when the machine door is switched on and off, do not violently open and close. In finishing, the shock vibration in the process of opening the door will lead to the processed surface with knife lines.

6) to the spindle speed, after the start of processing, otherwise due to the spindle start slowly, resulting in not to achieve the desired speed on the start of processing, so that the motor suffocated.

7) Do not place any tools or workpieces on the beam of the machine tool.

8) It is strictly prohibited to place magnetic tools such as magnetic suckers and dial gauge holders on the electric control cabinet, otherwise the display will be damaged.

12. The phenomenon of holding back in the process of new knife processing is very difficult. What parameters need to be adjusted at this time?

The reason why the processing is very laborious is that the power and torque of the spindle can not withstand the current cutting amount. The reasonable approach is to make the path again, reduce the depth of the cutting tool, the depth of the slotting and the amount of trimming. If the overall processing time is less than 30 minutes, the cutting state can also be improved by adjusting the cutting speed.

13. What is the function of cutting fluid?

Pay attention to adding cooling oil in metal working. The function of the cooling system is to take away the cutting heat and flying chips and play a lubricating role in the processing. Coolant will cut the belt, reducing the heat to the tool and motor, improving their service life. Take the fly chip away to avoid the phenomenon of secondary cutting. Lubrication can reduce cutting force and make machining more stable. In copper processing, the choice of oil cutting fluid can improve the surface quality.

14. What are the stages of tool wear?

Tool wear is divided into three stages: initial wear, normal wear, sharp wear.

In the early wear stage of the main reason for tool wear is that the temperature of the tool is low, and does not reach the best cutting temperature, at this time, the tool wear is mainly abrasive wear, such wear on the tool is relatively large, it is easy to lead to tool collapse. This stage is a very dangerous stage, not handled well, may directly lead to tool collapse knife failure.

When the tool has gone through the initial wear period, the cutting temperature of the tool reaches a certain value, then the main wear is diffusion wear, its role is mainly to lead to local peeling. As a result, wear is less and slower.

When the wear to a certain extent, the tool failure, entered a period of sharp wear.

15. Why should the tool be run in, how to run in?

Above we said that the tool in the initial wear stage, it is easy to collapse, in order to avoid the collapse of the phenomenon, we must run in the tool. The cutting temperature of the tool is gradually increased to a reasonable temperature. The experiments show that the tool life is increased by more than 2 times after running in using the same machining parameters.

The running-in method is to reduce the feed speed by half under the condition of maintaining the reasonable spindle speed, and the processing time is about 5~10 minutes. Small value for soft material processing and large value for hard metal processing.

16. How to judge severe tool wear?

1) Listening to the processing sound, there will be a harsh cry;

2) Listen to the sound of the spindle, the spindle appears obvious phenomenon of holding back rotation;

3) The vibration increased during the processing, and obvious vibration occurred to the spindle of the machine tool;

4) look at the processing effect, the bottom surface of the processed cutter grain is good or bad (if the beginning stage is so that the depth of the knife is too deep).

17. When should I change my knife?

We should replace the tool at about 2/3 of the limit value of the tool life. For example, the tool in 60 minutes of serious wear, the next processing, should start to change the knife in 40 minutes, and develop the habit of changing the knife regularly.

18. Can the tool with severe wear continue to be processed?

After severe tool wear, cutting forces can increase to three times normal. The cutting force has a great influence on the service life of spindle electrode, and the service life of spindle motor and the force are inversely proportional to the third power. For example, when the cutting force increases by 3 times, 10 minutes of processing is equivalent to 10*33=270 minutes of use of the spindle under normal circumstances.

19. How to determine the extension length of the tool in rough machining?

The shorter the extension length of the cutter, the better. However, in the actual processing, if it is too short to frequently adjust the length of the tool, which too affect the processing efficiency. Then how to control the extension length of the tool in the actual processing? Here's the principle:

Φ3 diameter of the knife rod extended 5mm can be normal processing. Φ4 diameter tool rod extended 7mm can be normal processing. Φ6 diameter tool rod extended 10mm can be normal processing. Try to go below these values on the knife. If the length of the knife is greater than the above value, try to control the depth of processing when the tool wear, which is a little difficult to grasp, need more exercise.

20. When processing, how to deal with the sudden occurrence of a broken knife?

1) Stop processing and check the current serial number of processing.

2) Check the broken knife and see if there is the body of the broken knife. If there is, take it out.

3) analyze the reason for the broken knife, this is the most important, why the tool is broken? We want to analyze from the above mentioned factors affecting the processing to analyze. But the reason the knife breaks is that the force on the knife suddenly increases. Or the path problem, or the tool jitter is too large, or the material is hard, or the spindle motor speed is not correct.

4) after analysis, replace the tool for processing. If there is no replacement path, it is necessary to process a serial number in advance of the original serial number. At this time, we must pay attention to the feed speed. One is because the hardening of the broken knife is serious, and the other is to run in the tool.

21. How to adjust the machining parameters when the rough machining is not good?

If at a reasonable spindle speed, the tool life is still not guaranteed, in the adjustment of parameters, to adjust the depth of the knife, first, then adjust the feed speed, and then adjust the lateral feed.

(Note: Adjust the depth of the cutter is also limited, if the depth of the cutter is too small, so too much stratification, although the theoretical cutting efficiency is high, but the actual processing efficiency is affected by some other factors, resulting in the processing efficiency is too low, then should be changed to a smaller tool for processing, but the processing efficiency is higher. In general, the knife depth can not be less than 0.1mm.)

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