Laser cutting and engraving equipment
There are many devices available on the market that can allow cutting and engraving of various materials such as metals, plastics, natural plastics, and composites. Material cutting is a process aimed at obtaining a specific geometry of a workpiece from a sheet of material. Depending on the degree of penetration into the material, the engraving process can be divided into marking, where the effect of the process is only to change the structure of the material's surface, 2D engraving, in which the engraved surface is parallel to the material's surface, and 3D engraving, which makes it possible to obtain three-dimensional images (such as reliefs). Among the many numerically controlled machines that make it possible to perform the processes discussed above, laser devices, which use laser beams of different wavelengths as the processing medium, are becoming increasingly popular. These devices can be divided into several groups according to different criteria, such as by purpose: cutting machines, engraving machines, engraving and cutting machines. However, since the above division is very often dependent on the material being processed, the most common distinction of laser machines is a criterion related to the type of laser beam used. The most commonly used lasers in industrial machines are CO2, Fiber, Mop, YAG, Green and UV beams. They differ in wavelengths and capabilities in terms of processing different materials. The different types of the most commonly used laser beams are described below.
CO2 – is a gas laser with a wavelength of 10.6 µm. The medium in which the laser beam is generated is a mixture of gases. Its main part is carbon dioxide. In addition, the gas mixture includes nitrogen, hydrogen and helium. The emission of the beam is possible after an electric pulse is delivered. Then the nitrogen atoms vibrate and then transfer energy to the carbon dioxide atoms, which leads to the emission of a photon and the generation of a laser beam. CO2 lasers with powers up to about 200W are used for cutting, marking and engraving plastic and natural materials, and for using engraving pastes to mark metal. When using a generator with higher power (in the order of several hundred watts or several kilowatts), it is also possible to cut metals.
Fiber - is a laser in which the beam is emitted inside an active optical fiber using laser diodes, and then transported to the laser head via an optical fiber. The wavelength of the Fiber laser is about 1.064 µm. As with CO2 lasers, the range of applications for Fiber lasers also depends on the laser power. Fiber lasers with powers on the order of tens of watts are mainly used in laser marking machines and are used for marking metals and some plastics. Fiber laser sources with powers of several hundred watts or a few kilowatts are used for metal cutting.
Mopa – is a laser that is based on the Fiber laser source in its characteristics. The difference is the use of an additional fiber amplifier in the Mopa laser, which scales the signal from the main low-power oscillator. The use of such an arrangement eliminates the occurrence of nonlinear effects that can cause changes in wavelength and beam power. The Mop laser is distinguished by the ability to manipulate the bandwidth and the ability to color mark metals with the selection of appropriate parameters.
YAG – beam is emitted from the active medium, which is a monocrystal by means of laser diodes (lamps) placed in the source. Unlike Fiber lasers, the beam is transported by means of a classical system composed of mirrors. Yag lasers can be used for metal cutting and at lower power sources for marking. The Yag laser has a much lower lifetime compared to Fiber lasers due to the more complicated beam generation system. At present, different types of YAG lasers are used on the market, which are characterized by different wavelengths, for example, the neodymium YAG laser emits a beam of 1.064 µm.
Green – unlike the previously mentioned lasers, whose wavelengths corresponded to the infrared band, the Green laser is a visible beam and its wavelength is about 532 nm. The beam is generated by a high-power diode laser pump. Due to the doubled frequency of the generated beam, spatial engraving of non-linear materials such as crystals and other plastics is possible.
UV – this laser is characterized by a wavelength of 355 nm (ultraviolet), so because of the smaller cross-section of the beam, precise marking is possible and smaller deformation and higher marking resolution can be achieved. UV lasers are used for precision marking of food, medical products and PCBs, among others.
Laser machines, depending on their purpose, can be characterized by different structures and the way the laser beam is guided. The main division of laser processing machines is the division into laser plotters/cutters and laser marking machines.
Laser plotters are most often used for cutting and engraving plastics, natural materials, composites (including plywood, Plexiglas, paper, laminates, wood, etc.). Laser plotters most often use a CO2 laser source. The principle of operation of the plotter is to feed a laser beam to a numerically controlled head with the help of a special electronic circuit and cooperating software. The movement of the laser head can be implemented in several ways, for example, by stepper motors or servo drives and gears with toothed belts, toothed bar gears or ball screw gears. The type of drive used depends mainly on the required cutting precision and the required movement dynamics for engraving. Laser plotters can operate in two modes. The first is cutting mode, in which the head moves according to vectors defined in the program. The second mode is engraving, during which the head moves along parallel lines inside the drawing area. Guidance of the optical beam is carried out by a system of mirrors (in the case of CO2 laser plotters). Nowadays, hybrid solutions are also introduced on the market, where in addition to the CO2 laser beam, the plotter is also equipped with a Fiber source, where the beam can also be guided by a system of mirrors or by means of an optical fiber. The hybrid solution gives the possibility of processing in addition to the previously mentioned metal materials (e.g. cutting thin films and engraving).
.
The second group of laser devices are laser cutters. Their principle of operation is analogous to laser plotters. The difference comes from the components used and the type of operations performed on the machine. Cutters are used for cutting materials, and are most often used for cutting metals or thicker sheets of plastic. Due to the need for greater precision and the weight of the components (e.g., larger laser heads), servo drives are most often used for the drive, along with gears with toothed rails or ball screws. Direct drives – linear motors are also increasingly used in modern machines. Laser cutting machines mostly use laser CO2, Yag and Fiber sources. Due to the development of Fiber sources, they are increasingly displacing the other technologies due to easier operation, higher efficiency, lower power consumption and definitely longer service life. In laser cutters, the beam can be transported by a system of mirrors (CO2, YAG) or by an optical fiber (Fiber). Laser cutters, due to the lower dynamics of movement in the return mode, are most often used for cutting materials, while it is also possible to mark details along the contour in the mode with limited laser beam power. This is a useful feature used, for example, to mark the numbers of cut details.
The last group of laser devices are laser markers. They are used for marking and engraving various materials depending on the type of laser beam used. Laser marking machines can be equipped with all the laser sources discussed earlier: CO2, Fiber, Mop, Yag, Green, UV. The characteristic that distinguishes marking machines from plotters and cutters is the way the beam is guided. In the case of marking machines, galvanometric scanners are used. Their principle of operation is based on a system of moving mirrors, which, based on signals from the control system, set themselves at an appropriate angle so as to scan the required area in the XY axes. In addition, the scanners are equipped with lenses that focus the laser beam. The advantage of using a galvo scanner is the ability to control the position of the laser beam without changing the position of the entire head. This solution gives high precision and very high dynamics of movement, which is practically unachievable with mechanical drives due to their mass and inertia. In addition, galvo scanners are characterized by a compact, closed structure, so the risk of dirt or damage to the mirror system is much lower than in the case of classical solutions. In some cases, laser markers can also be used for cutting materials. For example, for cutting precise patterns from paper on CO2 laser cutters, or for cutting thin metal foils on a Fiber laser marker.
Depending on the purpose of the device and the capabilities shown above, laser devices are used in many industries. In the case of CO2 laser plotters, the range of their applications is very large. Using them, it is possible to make various types of products for the advertising industry, such as personalized lettering, logos, gadgets, banners, advertisements. In addition, these machines can also be used in the furniture industry for cutting and engraving elements made of wood, in the clothing industry for cutting blanks for clothes, in the paper and packaging industry, for example, for cutting decorations and invitations from paper, cardboard packaging, etc. The range of applications of CO2 laser plotters is very wide and depends largely on the needs and creative ingenuity of those operating the machines. In addition to the aforementioned industries, an interesting application is the use of laser plotters in the stone industry, e.g. for engraving images or inscriptions, and in the electronics industry, e.g. for cutting membrane keyboards for devices. As you can see, the application area of CO2 laser plotters is very wide. The situation is similar for laser marking machines. In addition, marking machines equipped with sources designed to work with metals (e.g., Fiber, Mopa, Yag) are used in other industries where metal products are used, such as in the jewelry industry for marking designs on jewelry or in many manufacturing companies where it is necessary to mark products, for example, serial numbers, barcode marking of details, etc. In addition, laser marking machines are used in all other industries that require marking of products e.g. logos, serial numbers, information on product parameters, etc.
Because of the relatively low cost of the machines presented above, companies and plants very often decide to purchase the machine, because of the quick return on investment. Small companies that are starting out in the initial stage decide to have outside companies perform the orders as a service, but due to the high cost of services and logistical requirements such as packaging and shipping of material, they quickly decide to purchase a machine. The decision to purchase a machine is most often determined by the volume of workpieces to be produced. For example, companies that need to mark every product coming out of the factory very often include a marking device in the production chain so as to speed up the whole process.
The situation is somewhat different for laser cutters of larger size and power. They are used in many industries related to the metal industry to cut details from sheets of metal. The most commonly processed materials on laser cutters are steels (black steel and stainless steel) as well as aluminum. In this case, many companies face the decision to invest in a machine and also decide on the machine specifications. In the case of high demand for their own production, companies decide to purchase a machine in terms of their needs and on this basis choose the laser source and other parameters of the machine, such as the working field. Many companies, in order to avoid machine downtime, additionally decide to offer cutting services to third-party companies, which enables a faster return on the machine purchase cost. In such a case, the most universal machine parameters are selected, so as to achieve versatility and the ability to offer cutting of materials of different thicknesses and formats.
The laser equipment market is developing at a very fast pace. With the development of laser sources, more powerful and more durable laser sources are being introduced. In addition, sources at the same powers are becoming more compact. Solutions aimed at increasing the functionality of machines are also appearing on the market. One such solution is hybrid laser plotters, which can be equipped with a CO2 and Fiber laser source. These sources can be used alternately. By using two laser sources, the plotter can be used to process both plastics, natural materials, composite materials and metals. Another innovative solution is the use of marking heads in other numerically controlled machines, e.g. milling plotters, cutting plotters or cutting-big plotters. Due to the compact dimensions of the marking head, it does not take up much space while it gives additional functionality in the form of the possibility of marking the manufactured parts with, for example, serial numbers or barcodes.
In addition to the development of optical components of laser sources such as sources, beam guiding elements, lenses, etc., the development of the laser equipment market is also linked to the implementation of increasingly advanced solutions on the side of drive systems. This is aimed at creating solutions that meet the parameters of optical systems so that the full potential of laser sources can be realized. One such solution is the use of linear drives to realize head axis motion. The use of such drives makes it possible to achieve very high dynamic motion, as well as high precision. In addition to the use of linear drives to realize the movement of laser heads, it is also possible to use them to drive the work tables of laser marking machines. The use of such a table allows to extend the working field of the marking machine (the field is limited by the size of the lens used) while maintaining the precision provided by the galvo optical drive.
Sources:
- https://atmsolutions.pl/
- https://atmsolutions.pl/newsroom
