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In the field of laser cutting, power, speed and parameters play a decisive role in cutting results. Understanding what they mean, how they relate to each other, and how to set them correctly is critical to achieving high quality laser cutting. These key elements are described in more detail below.
Laser cutting power, one of the most important parameters of laser cutting, refers to the amount of energy in watts that the laser delivers to the material being cut, and is directly related to the intensity of the laser beam. Higher laser power means a greater concentration of energy, enabling faster and more efficient cutting of different materials.
The power of the laser determines its ability to penetrate thicker materials and cut cleaner edges, for example, when cutting thick sheet metal, high power lasers are the only way to meet the cutting requirements, while low power lasers are often not up to the task.
The cutting speed of a laser cutting machine is closely linked to the thickness of the material as an interdependent whole. When cutting thicker metals, more energy is expended, more time is spent, and more cutting resources are required to obtain the desired part. However, slower cutting speeds allow the laser cutter to have more cutting power and more penetration time.
However, this needs to be weighed carefully in the quest to balance efficiency with value, as slow cutting speeds, while helpful in cutting thick materials, can increase production costs, lengthen production time, and impact delivery efficiency, while fast cutting can lead to problems such as large amounts of distortion or errors in the material.
Different thicknesses of materials have different requirements for laser power, with thicker materials requiring a high power laser beam to penetrate the material more deeply and quickly. For example, for thin metal sheets, low power laser may be able to cope with, but for more than ten millimeters or even thicker sheet metal, high power laser becomes a necessity. Moreover, while considering the cutting speed, the laser power should be reasonably matched to the thickness of the material in order to achieve efficient and high-quality cutting results.
Laser Wavelength: laser cutting commonly CO2, crystal, fiber, these three types of lasers, they use different base materials to produce different wavelengths of laser. Each material absorbs and reflects different wavelengths differently, so choosing the right laser for the workpiece is a critical first step.
CO2 Laser Cutting: A CO2 laser cutter generates a laser beam by passing an electric current through a gas chamber filled with carbon dioxide, helium, hydrogen and nitrogen, with an end mirror that focuses the laser beam to a single point. the wavelength of the CO2 laser is in the infrared (invisible) region (0.6µm), and at room temperature, materials with bright surfaces such as aluminum, gold, silver, and copper reflect its long infrared wavelengths, while steel absorbs about 10 percent of the laser’s energy. The steel absorbs about 10% of the laser energy, so CO2 laser cutting is more suitable for cutting insulating materials such as wood, paper and plastics, and less suitable for cutting reflective and electrically conductive surfaces.
Crystal Laser Cutting: The neodymium-yttrium-aluminum-garnet (Nd:YAG) laser beam is in the shorter infrared radiation range (1.06µm), which is better absorbed by reflective metals, and high-power Nd:YAG lasers can cut both metallic and non-metallic surfaces, and even process ceramics in some cases. In fact, both CO2 and Nd:YAG lasers can overcome material reflectivity and process a wider range of materials at high power intensities, which can also be achieved by changing external parameters such as heating the material to be cut.
Fiber Laser Cutting: Derived from quartz glass and rare-earth metals, fiber lasers, with a wavelength of 1.064µm, have a higher beam power and a narrower focal spot diameter, and in many ways outperform CO2 and crystalline laser beams. They are able to process a wide range of insulating materials such as metals, non-metals, glass, etc., and also have solutions for reflective metals, which make them very versatile.
Laser Power and Intensity: Laser power and laser intensity are often mentioned together and sometimes confused, but they have different meanings. The amount of energy emitted per second is referred to as laser power, while laser intensity is the power divided by the area per unit of material. Don’t confuse a high-power beam with a high-intensity beam. Intensity depends on the width of the focal point; the narrower the laser beam, the higher the laser intensity.
Beam Polarization: The reflectivity of the laser on the melted surface of the material to be cut depends on the beam polarization, that is, the orientation of the electric field with respect to the direction of propagation. Depending on the orientation of the field, there are cases of planar polarization, circular polarization, elliptical polarization, and random polarization, each of which absorbs and reflects differently on the material surface. For example, circular polarization produces a uniform slit width, whereas elliptical or linear polarization causes variations in slit inclination, and beam polarization affects the quality of the slit depending on the polarization plane and cutting direction.
Focus Position: The focus setting (also known as Z-axis offset) relates to the ability to maximize the use of laser power for cutting material. If the focus is too low or too high, the material will not be cut efficiently due to reduced energy density, and if the laser beam is out of focus, it will not be cut at all. Ideally, the focus should be centered on the thickness of the material so that the laser does not create a tapered cutting edge that cuts unevenly across the top and bottom of the workpiece. Generally, the focal point position should remain constant during material processing, and it is also affected by factors such as the shape of the laser beam, pattern, lens contamination, and the temperature of the cooling water, which together determine the quality of the final cut part.
Laser Cutting Speed: Cutting speed is another important laser parameter that needs to be optimized according to the thickness of the workpiece. Cutting speed is related to the energy loss in the cutting process, the faster the speed, the smaller the energy loss, the more efficient operation. The slower the speed, the greater the energy loss and the less efficient the cutting process. Cutting too fast or too slow can be problematic; slow speeds can lead to residue and scorching of the material, creating a large heat affected zone. Too fast a speed can cause streaks to appear on the cutting edge, so finding the optimum balance between cutting speed and laser power for a given material is key.
Auxiliary Gases and Gas Pressure: The auxiliary gases (also known as booster gases) used in laser cutting operations play an important role in determining the cutting speed, the quality of the cut edge, and the life of the laser lens. Generally, the cutting speed is proportional to the laser power; the higher the laser power, the faster the cutting speed, and vice versa. The main purpose of the auxiliary gas is to remove molten metal from the edges and to protect the optics from damage during processing, as well as to cool the material and prevent the creation of a large heat affected zone.
Nozzle Diameter and Focusing Distance: The nozzle is responsible for the delivery of the assist gas and is coaxial to the laser beam. Its role is to provide the assist gas to the cutting area and to stabilize the surface pressure to minimize the splashing of the molten metal. The nozzle diameter is an important parameter to be selected according to the type and thickness of the material, while the out-of-focus distance is the distance between the nozzle and the workpiece, which determines the gas flow pattern and ultimately affects the quality of the cut.
In laser cutting, the parameters are not fixed, but have to be adjusted according to the actual needs. For example, if you want to achieve a deeper, darker engraving effect on wood, you can increase the power value to allow more energy into the material. Conversely, decreasing the power carves lighter and lighter colors. The same is true for other parameters, in order to achieve different cutting or engraving visual effects, based on the material characteristics and the desired quality of the finished product, to adjust the parameters in small increments, so as to accurately find the best combination of parameters suitable for specific application scenarios.
Many advanced laser cutting machines have preset parameters for various materials in the software database, and these preset values have been tested and verified repeatedly by the manufacturers and can be applied automatically, which reduces the workload and makes processing more convenient. However, if minor changes are required, the operator can manually edit and enter the values into the software that controls the laser cutting machine.
If the parameters are set from scratch, the general principle is that when engraving and cutting the material, the high speed and low power settings will be used first, and after starting the operation, the software will automatically adjust the parameters according to the actual situation to achieve the best results. When cutting test pieces, the operator can adjust the parameters to get a burr-free, perfect cut edge.
At the same time, operators need to be trained to understand the consequences of increasing or decreasing cutting speed, gas pressure, and laser power during the cutting process, and it is critical to understand the relationship between laser parameters and material interactions. The key is to grasp the relationship between the auxiliary gas and speed in stainless steel cutting to ensure that the right amount of molten metal is removed at the right time to get a perfect cut edge.
Although there are no strict limits on the color of the marking line itself, red is the most commonly used color because it is highly recognizable and easier for the machine to detect. If red is not used, try to use a marker with a striking color, otherwise the machine may not be able to recognize it accurately, which in turn may affect the cutting results.
Before starting a cutting project, make sure that the drawing has been scaled properly according to the dimensions of the laser cutting machine, depending on the machine software, so as to ensure that the cutting process runs as smoothly as possible, otherwise problems such as cutting deviations may occur.
There are many parts of a laser cutting machine that need to be kept clean to maintain good machine performance, areas like support bars and pallet tracks. Also, unclean machining areas can present a danger from alumina thermite, a mixture of metal oxides and aluminum commonly found in environments where mild steel is processed, which, once ignited, produces extremely high temperatures, enough to melt metal containers and ignite the contents. So try to keep areas such as waste drawers, ventilation ducts, dust collectors, etc. free of dust, dirt, debris and grease.
During the laser cutting process, it is a health and safety hazard for other people to hang around in the operator’s room, especially if they are carrying food and drink. It is also important that laser cutting operations are not left unattended. Even though the cutting process is automated, hardware failures can occur and must be supervised at all times to ensure safety.
Removing the workpiece too quickly after cutting can damage the laser cutting machine as the workpiece can collide and damage the cutting head or change its alignment, ultimately affecting the quality of the entire cutting project.
Laser cutting power, speed and parameters work together and influence each other to determine the final result of laser cutting. Understand the meaning of each parameter, the role of each parameter and the relationship between them, master the correct parameter setting method, and avoid those common errors affecting the cutting performance, for those engaged in laser cutting work is critical.
Only in this way can we give full play to the advantages of laser cutting technology, to achieve high quality, high efficiency cutting operations, to meet the requirements of different industries for cutting accuracy, quality and productivity, to promote the laser cutting technology in more areas of wide application. I hope that through the introduction of this article, can help you better understand and utilize the knowledge related to laser cutting, enhance the level of practical operation.
