As common equipment in industrial manufacturing, fiber laser cutting machine is widely welcomed by users for their high precision and fast cutting speed. It should be noted that the cutting accuracy of the laser equipment is an important factor in judging the quality of the laser cutting machine.
The cutting process of the CNC metal laser cutting machine is complex, and there are many influencing factors. Therefore, if the control is improper, the cutting quality and precision of the laser cutting machine will be greatly affected. This may result in suboptimal cut quality. Therefore, it is necessary to systematically study and analyze the factors affecting the cutting quality in order to obtain better results.
Standards For Judging the Cutting Quality of Laser Cutting Machines
The laser-cut section will form vertical lines. The depth of the line determines the roughness of the cut surface. The lighter the line, the smoother the cut. Roughness affects not only the appearance of the edge but also the friction properties. In most cases, roughness needs to be minimized, so the lighter the texture, the higher the quality of the cut.
If the sheet metal thickness exceeds 10mm, the verticality of the cutting edge is very important. When moving away from the focal point, the laser beam becomes divergent and the cut widens towards the top or bottom depending on the position of the focal point. The cutting edge deviates a few hundredths of a millimeter from the vertical. The more vertical the edge, the higher the quality of the cut.
3. Cutting Width
Generally speaking, the cutting width does not affect the cutting quality. The cutting width only has a significant impact when forming particularly precise contours inside the part. This is because the cut width determines the minimum inward warping of the profile. As the sheet thickness increases, the cutting width also changes. Increase. Therefore, in order to ensure the same high precision, the machining area of the workpiece in the laser cutting machine should be constant regardless of the width of the kerf.
When cutting thick plates at high speed, the molten metal does not appear in the kerf below the vertical laser beam but is ejected behind the laser beam. As a result, curves are formed on the cutting edge, which follows the moving laser beam. To correct this problem, reducing the feed rate at the end of the cutting process can greatly eliminate the formation of lines.
The formation of burrs is a very important factor in determining the quality of laser cutting. Since burr removal requires extra work, the severity and number of burrs can visually judge the quality of the cut.
6. Material Deposition
The laser cutting machine first coats the surface of the workpiece with a layer of special oily liquid, and then begins to melt and perforate. Vaporization and various, materials do not require customers to use the wind to remove the cut, but upward or downward discharge can also form deposits on the surface.
7. Dent and Corrosion
Sink and corrosion adversely affect the trimmed surface, affecting appearance. They appear in cutting mistakes that should generally be avoided.
8. Heat Affected Zone
In laser cutting, the area near the cut is heated. At the same time, the structure of the metal changes. For example, some metals will harden. The heat-affected zone is the depth of the area where the internal structure changes.
If the part is heated sharply from cutting, it will deform. This is especially important in fine machining, where contours and connections are often only a few tenths of a millimeter wide. Controlling laser power and using short laser pulses can reduce part heating and avoid deformation.
What are the factors that affect the quality of fiber laser cutting?
Laser Output Power
For the continuous wave output laser, the size of the laser power and the quality of the model will have an important impact on the cutting. The size of the laser power directly affects the thickness of the steel plate that can be cut. The higher the ingenuity rate, the thicker the thickness of the material that can be cut. At the same time, it affects the accuracy of the workpiece size, the width of the cutting, and the roughness of the cutting surface.
We often set the maximum power of a metal laser cutter for higher cutting speeds, or to cut thicker materials. But that’s not always the right choice.
Sometimes the laser beam pattern (the distribution of laser energy across the cross-section) is important. Also, when you increase the laser power of the metal laser cutting machine, there are some changes in the laser mode. It is often found that the highest power density and best cut quality occur at the focal point where the power is less than the maximum.
When the laser power of the laser metal cutting machine is too small, the heat of the material may be insufficient. Furthermore, the closer to the lower edge, the lower the temperature of the molten product. As a result, the high-pressure airflow may not completely blow the slag away, causing them to stick to the cutting edge.
If the laser power of the metal laser cutter is too high, the heat input may be excessive. Then the melting range of the workpiece will be larger than the range that the high-pressure airflow can blow. As a result, part of the molten metal remains on the sheet, resulting in excessive combustion.
Therefore, you need to pay special attention to the laser power according to your specific cutting conditions.
Beam Characteristics of Lasers
The kerf width of laser cutting has a lot to do with the focused spot diameter. Since the power density and energy density of laser irradiation is related to the diameter of the laser spot, in order to obtain a larger power density and energy scale, the spot diameter is required to be as small as possible in the laser cutting process.
Laser Cutting Speed
The cutting speed has a great influence on the cutting quality. Generally speaking, the cutting speed is inversely proportional to the density and thickness of the material being cut when other parameters remain unchanged. The right cutting speed will make the cut surface look smooth and no dross will be produced on the lower part. If the cutting speed is too fast, the material will not be cut through, causing sparks to fly, slag on the lower part, and even burn out the lens. On the contrary, if the cutting speed is too slow, it is easy to cause over-melting of the material, widening of the slit, and even over-melting of the workpiece.
Material cutting requires the use of an assist gas, which is usually launched coaxially with the laser beam to protect the lens from contamination and to blow away slag at the bottom of the cutting zone. When the auxiliary gas can generate enough pressure, the cutting is completed and the slag is transparent. Both the pressure and type of gas affect the roughness of the cut section and the generation of slag.
Material Surface Roughness
We all know that fiber laser cutting has a good flexible processing method and is not limited by the shape of the workpiece, but it is limited by the surface roughness and cannot achieve a perfect cutting effect. The smoother the surface of the material, the better the cutting quality will be. Therefore, the stability of the machine tool is also very important. It is necessary to ensure the working environment of laser cutting.
The thickness of metal material
The output power of the fiber laser cutting machine is generally 500W and 1000W, the high power is more than 2000W fiber laser cutting machine, and the fiber laser cutting machine with power below 1000W is suitable for cutting carbon steel with a thickness of less than 14mm and stainless steel products with a thickness of less than 6mm. The cutting quality of these types of products is very good under the corresponding material thickness, and the cutting speed is fast, which can ensure the working efficiency and cost-saving conditions of laser cutting. When these two materials exceed the applicable cutting thickness, the cutting speed will be slower, the cutting quality will be worse, and thicker materials will not be able to be cut. In contrast, if the thickness is smaller than the applicable cutting thickness, such as 1mm stainless steel, the cutting quality will be very good, and it can be applied to downstream links without subsequent processing.
Tips for Improving the Cutting Quality of Laser Cutting Machines
When using a metal laser cutter, you may encounter all kinds of troubles. Such as burrs, burrs, deformation, cut-through failure, discoloration, etc. Every failure requires you to check the cutting parameters or conditions of the metal laser cutting machine.
If the following faults occur, please check your metal CNC machine according to the given method first. If the problem persists after the machine self-test, you need to contact the machine supplier or consult a professional.
First, check whether there is any problem with the laser output of the fiber laser cutting machine. Remember to check that the spot is circular and that the spot is coaxial with the center of the nozzle. Then check the optical system of the fiber laser machine for foreign objects. For example, fine particles, dust, or slag on the lens. Be sure to check the lens for tiny cracks. All of these affect the delivery of laser power.
If the above problems are solved, you can consider changing the cutting parameters of the laser cutting machine or the purity of the gas. You can find suitable cutting parameters by practicing multiple cuttings.
When cutting metal with a fiber laser cutter, the area around the cut is heated. At the same time, the structure of the metal changes. For example, some metals may harden after being cut by a laser CNC metal cutter.
Any dents or corrosion can adversely affect the cutting edge of a metal laser cutter. They are cutting errors that should generally be avoided. If the metal is heated up sharply during the cutting process, it will deform.
To avoid deformation, you can control the laser power or use short laser pulses to reduce the heating of the metal.
Solve the problem of cut-in failure
You can try to slow down the cutting speed of the CNC metal laser cutting machine appropriately. In addition, timely and properly clean the contaminated mirror and replace the focusing mirror.
Readjust the optical path of the CNC laser cutting machine. Therefore, adjust the focus until the laser spot is concentric with the center of the nozzle.
When cutting copper and aluminum, the surface should be polished in advance to deal with the problem of high reflectivity.
Remember to clean up the debris inside the nozzle of the laser metal cutting machine in time. Increase or decrease the gas pressure according to the actual situation. In addition, replace the distilled water in the cooling system in time.
On the whole, in order to achieve a higher cutting effect, the selection of process parameters before cutting and the analysis of quality problems after cutting are indispensable. Timely analyze quality problems, adjust relevant process parameters, and improve the process.
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