It is only in recent years that fiber laser cutting technology has begun to be widely used in the industry. Many companies have realized the advantages of fiber lasers.
With the development of cutting technology, fiber laser cutting has become one of the most advanced technologies in the industry. In 2014, the fiber lasers surpassed CO2 lasers to occupy the most market share of laser sources.
Plasma, flame and laser cutting techniques are three common thermal cutting methods, while laser cutting can achieve the best cutting quality, especially for fine cutting and hole blanking with the diameter-to-thickness ratio less than 1:1. Therefore, laser cutting technology is also the first choice of fine cutting.
Fiber laser cutting has drawn great attention in the industry because it provides both cutting speed and quality which is achievable by CO2 laser cutting, while significantly reducing maintenance and operating costs.
Laser Cutting Machine Market and Trends
One is a CO2 laser cutting machine that was converted from an industrial laser about 25 years ago, and the other is a fiber laser cutting machine that was officially converted from an industrial laser about 10 years ago.
From the number of laser cutting machines sold in China’s sheet metal equipment market in recent years, CO2 laser cutting machines account for 40% and fiber laser cutting machines account for 60%.
Although essentially 100% of laser cutters sold on the market in 2007 were CO2 laser cutters, we know that fiber laser cutters have gained momentum in recent years and are gaining market acceptance and the number of units sold is gradually expanding.
Fiber laser vs. CO2 laser
While the current market trend favors fiber laser cutters, are fiber laser cutters really the best choice?
Due to the different physical characteristics of CO2 laser and fiber laser, the laser processing process differs between the two.
Of course, the two actually have their own strengths and weaknesses, and each has advantages and disadvantages depending on the object being processed.
The CO2 laser is a gas beam obtained by excitation of carbon dioxide molecules, and its wavelength is 10.6μm, while the fiber laser is a solid laser obtained by placing a crystalline Yb (ytterbium) compound as a medium in optical fiber and irradiating the crystals with a light beam, and its wavelength is 1.08μm.
The physical characteristics of the different wavelengths have a significant impact on the processing characteristics of the two.
The original concept of the fiber laser was recognized because it was a laser that could propagate through fibers.
The reason for being able to propagate through the optical fiber is precise because of its wavelength of 1.08μm.
The advantage of using optical fibers for propagation is the long life of the optical components and the high maintenance performance.
CO2 laser cutting machines transmit laser light from the oscillator to the processing point with the aid of reflect lens, generally in an optical path that is isolated from the outside air.
Although the inside of the optical path is filled with air free of common dust and foreign objects, the surface of the reflector may become covered with dirt even after prolonged use, and needs to be cleaned.
In addition, the reflector itself will wear out from absorbing small amounts of laser energy and will need to be replaced.
Plus, to transmit the laser from the oscillator to the processing point, multiple reflectors are used to adjust the angle of the laser reflection.
So it requires a certain amount of technical skills and management to maintain proper operations.
However, with fiber laser cutters, the laser is transmitted via a single fiber from the oscillator to the processing point.
This fiber is commonly called a light guide fiber.
Since no optical components such as reflectors are required and the laser is transmitted in a light guiding fiber that is isolated from the outside air, the laser is virtually invisible.
Strictly speaking, however, the laser is transmitted repeatedly in the periphery of the optical fiber, so the optical fiber itself is somewhat depleted.
However, this one will last several times longer compared to the reflectors used in CO2 laser cutters.
In addition, if the transmission path is above the minimum curvature of the guiding fiber, the path can be freely determined, so it is easy to adjust and maintain.
The two also differ in the process of laser generation (laser oscillator construction).
A CO2 laser oscillator generates a laser by placing a gas mixed with CO2 in the discharge space.
In order to ensure that the resonance length derived from the laser output power is functioning properly, optical components are placed inside the oscillator, and the optical components inside the oscillator need to be cleaned and replaced periodically.
Fiber laser oscillators, as just mentioned, generate the laser inside the fiber and are isolated from the outside air with no optical components, so there is little need for regular maintenance.
The maintenance cycle for cleaning, etc. is set at approximately 4000 hours for CO2 laser oscillators and approximately 20,000 hours for fiber laser oscillators.
The aforementioned can be said to have great advantages for fiber laser cutters in terms of longevity and maintenance performance.
In addition, we can also try to compare them in terms of operating costs such as power consumption.
The photoelectric conversion rate of CO2 laser oscillators is said to be about 10-15%, while that of fiber laser oscillators is about 35-40%.
Fiber laser cutters are able to keep the power consumption of cooling devices such as chillers even lower due to the high photoelectric conversion rate, so less electrical energy is converted into heat dissipation.
In general, the oscillator of a fiber laser cutter requires a higher degree of accuracy in managing the cooling temperature of the oscillator compared to a CO2 oscillator.
However, for the same laser output power, about 1/2 to 2/3 of the cooling capacity of a CO2 laser oscillator for a fiber laser cutter is sufficient.
Therefore, considering the power consumption of the laser cutting machine, the fiber laser cutting machine can be operated with about 1/3 of the power consumption of the CO2 laser cutting machine, which can be said to be a very energy-efficient laser cutting machine.
Differences in processing characteristics
In the processing of CO2 lasers and fiber lasers, there is a significant difference between the two due to the difference in their respective wavelengths.
Comparison of processing speed between CO2 laser cutting machine and fiber laser cutting machine in processing stainless steel. All laser outputs are 4kW.
We can see that in the field of plate thickness of 4.0 mm or less, the fiber laser cutting machine is able to process at 2 to 3 times the cutting speed of the CO2 laser cutting machine.
Why is there such a big difference in processing speed, even at the same output power?
First of all, it can be argued that it is because of the large differences in the part of the absorption rate of laser energy into metallic materials.
Not only metallic materials but also in everything in the world, due to the different physical properties of matter, the absorption of light energy at different wavelengths of light varies.
For example, the stainless steel material cited above has an absorption rate for CO2 lasers of about 12%, while the absorption rate for fiber lasers is about 35%, a difference of about 3 times.
The high absorption rate refers to the very short time it takes for the laser to convert light energy into heat energy and then melt the metal material after it has been irradiated, making it possible to create a cutting process at a very fast rate.
If you want to cut quartz glass with a laser cutter, you can cut it with a CO2 laser cutter, but not with a fiber laser cutter.
This is due to the physical principle that quartz glass absorbs the wavelength of a CO2 laser, but does not absorb the wavelength of a fiber laser and penetrates it.
In addition, in the field of cutting highly reflective materials such as aluminum and copper, the fiber laser has an advantage over CO2 laser cutting.
This is also due to the principle that metal materials absorb the wavelength of the fiber laser better.
When comparing the processing speed of stainless steel materials, we can see that in the field of plate thicknesses over 6.0 mm, the two speeds are essentially the same.
From the point of view of the cutting process, it is more important to refer to the factor of how to remove the molten metal more efficiently than to refer to the factor of how the metal melts instantly.
When cutting with a laser, the auxiliary gas (generally nitrogen, oxygen, etc.) is injected into the processing point while the laser is directed at the material to achieve excellent processing conditions.
Different auxiliary gases are used for different materials of the cutting object. In addition, another major function of the auxiliary gas is to isolate the molten metal from underneath the material.
In the case of thick plates, an auxiliary gas is required to obtain a good cutting condition, which isolates the metal to be melted from underneath the lower part of the material and ultimately increases the processing speed.
However, from the point of view of processing area and cutting quality, it can be said that CO2 laser cutting machines are superior.
It has been about 30 years since the CO2 laser machine was first introduced to the industry, and many of its features have been thoroughly studied, making it possible to process a wide range of materials from thin to thick plates.
In addition, the processing technology has become so mature that it can guarantee a certain processing quality, and we have not only the processing technology to cut various shapes, but also the processing technology to ensure a certain roughness of the cut surface.
There are still some challenges to be solved when it comes to ensuring the quality of cutting with fiber laser cutting machines.
Especially in the field of plate thickness more than 3.0 mm, the products processed by the fiber laser cutting machine, there will be some obvious small particles attached to the bottom of the cutting surface is difficult to peel off the surface, these small particles are often referred to as scum.
In addition, the cutting surface is rougher than that of CO2 laser cutting machines.
This is a phenomenon caused by the above-mentioned property of high absorption of metallic materials.
Laser processing is a process in which a laser is reflected onto the surface of a material and then the metal is melted and falls down.
When a fiber laser is reflected on a metal surface with a high absorption rate, it causes back-absorption to melt the metal on the cutting surface, resulting in a rough cut section after cutting.
Sample cut by CO2 laser cutting machine (20mm stainless steel)
The processing quality is one of those items that are difficult to put a numerical value on, so many customers don’t pay much attention to it when choosing a laser cutter.
However, the aforementioned problems with scum are related to processing quality.
Fiber laser cutting machines can be used to control costs even at high speeds.
After the laser cutting process, if there is a subsequent process such as scum removal, the total processing cost is about the same as that of a CO2 laser cutting machine.
This means that you need to pay more attention to the quality of the processing by the laser cutter.
Laser cutting machine kinematics
Although I used the concept of fiber laser and CO2 laser to make a comparison, is it enough to actually make that comparison when choosing a laser cutter?
The concept of fiber optics and CO2 is always a comparison of the constituent oscillators of a laser cutter.
In the composition system of the laser cutting machine, there are also called X, Y, Z drive axis, the movement of this drive axis performance and control performance is also a big component.
In addition to round, square and rectangular holes, laser cutting machines can also process complex shapes such as odd-shaped holes, wedges and bumps.
Therefore, no matter how fast the machining speed is, if the kinematic performance of the XY drive axis, which determines the shape to be machined, is low, it is hopeless to shorten the cutting time.
If the processing speed is 40m/min with a fiber laser machine and 20m/min with a CO2 laser cutting machine, will the processing time of the fiber laser machine be twice as fast as the CO2 laser cutting machine, and will the processing time of the CO2 laser cutting machine be 1/2 as fast when processing a certain shape?
The answer becomes NO if the machining shape is complex and the number of holes is high.
In order to clearly show the difference in processing speed, it is necessary to improve the kinematic performance of the drive shaft, especially the acceleration and deceleration ability during cutting processing.
Combined capabilities of laser cutting machines
With high acceleration and deceleration performance, a strong, highly rigid frame is required that can withstand its kinematic performance.
In order to maintain the processing accuracy of the product, it is necessary to have an internal structure that can control high motion.
Maximizing the laser processing capability of the oscillator requires an increase in the overall capability of the laser cutting machine, including the driveshaft.
Because the components of a fiber laser cutter are relatively simple, it is possible to build a fiber laser cutter of a certain quality without laser processing technology when considering the design and manufacture of a laser cutter.
In addition, many of the components of a fiber laser cutting machine are available in the market. And the processing capability of the cutter made by assembling these components is also good.
This is one of the reasons why there has been a recent proliferation of manufacturers manufacturing and selling fiber laser cutters.
However, CO2 laser cutting machines require a lot of processing techniques such as laser transmission, so it is easy for differences in characteristics and performance to occur between laser cutting machine manufacturers.
A true laser cutting machine manufacturer should have mature technology and the ability to design and manufacture CO2 laser cutting machines, as well as the processing technology accumulated from the production of CO2 laser cutting machines that can be used to design and manufacture fiber laser cutting machines.
Although machining accuracy and quality are difficult to express numerically, the best choice is a laser cutting machine that can consistently maintain a high level of accuracy and quality, as well as high kinematic performance.
However, it is necessary to make a cool judgment before making a decision based on the materials of the processing.
A fiber laser cutter is the best choice if the material to be processed is thin, the production volume is high, and you want to control the processing costs.
However, if thicker than 6.0mm is required in many cases, or if a certain processing quality is required, a CO2 laser cutting machine is suitable.
The follow-up operation requires a separate process, and the total processing cost is very high when done manually.
When choosing a laser cutting machine, please make comprehensive judgments not only about the laser process, but also about your product and manufacturing.
The Advantages of Fiber Laser Cutting
It provides both the cutting speed and quality that carbon dioxide laser cutting can achieve and significantly reduces the cost of maintenance and operation.
The most important and significant advantage of fiber cutting technology should be its energy efficiency. The most important and significant advantage of fiber cutting technology should be its energy efficiency.
For each power unit of carbon dioxide cutting system, the actual general utilization rate is about 8% to 10%. As for the fiber laser cutting system, the user can expect higher power efficiency which is about 25% to 30%.
In other words, the overall energy consumption of the fiber cutting system is about 3 to 5 times less than that of the carbon dioxide cutting system, which makes the energy efficiency increased to more than 86%.
Fiber lasers have short-wavelength characteristics that increase the absorption of the beam by the cutting material and are capable of cutting materials such as brass and copper as well as non-conductive materials.
A more focused beam produces a smaller focus and a deeper focal depth so that the optical fiber laser can quickly cut thin materials and more efficiently cut materials of medium thickness.
When cutting materials of thickness to 6mm, the cutting speed of 1.5kw fiber laser cutting system is equivalent to that of 3KW carbon dioxide laser cutting system, because the operation cost of fiber cutting is lower than that of ordinary carbon dioxide cutting system, so this can be understood as the output increases and the commercial cost decreases.
There are also maintenance problems. The CO2 laser system requires regular maintenance: the reflector requires maintenance and calibration, and the resonant cavity requires regular maintenance also.
However, the fiber laser cutting solution requires virtually no maintenance.
CO2 laser cutting system requires CO2 as the laser gas.
Due to the purity problem of CO2 gas, the cavity will be polluted and need to be cleaned regularly.
It costs at least $20,000 a year for a system of kilowatts of carbon dioxide.
In addition, many CO2 cuts require high-speed axial-flow turbines to deliver laser gas, and turbines require maintenance and renovation.
Finally, compared to CO2 cutting systems, fiber cutting solutions are more compact and have less impact on the ecological environment, so less cooling is required and the energy consumption is significantly reduced.
The features of less maintenance and higher efficiency make optical fiber laser cutting systems to emit less carbon dioxide than CO2 laser cutting systems and to be more environmentally friendly.
Fiber laser has a wide range of applications, including laser fiber communication, industrial shipbuilding, automobile manufacturing, sheet metal processing, laser engraving, medical equipment and so on.
Fiber laser has a wide range of applications, including laser fiber communication, industrial shipbuilding, automobile manufacturing, sheet metal processing, laser engraving, medical equipment etc. With the continuous development of technology, its application is still expanding.
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