Laser cutting is a technology that uses lasers to cut materials, and is commonly used for industrial manufacturing applications, but is also being used by schools, small businesses and enthusiasts. Laser cutting works by directing the output of the most frequent high power laser through optics. Laser optics and CNC (computer numerical control.) Used to direct the material or laser beam produced. Typical commercial lasers for cutting materials involve motion control systems to follow the CNC or G-code of the pattern to be cut into the material. The laser beam focuses focused on the material, which then melts, burns, evaporates, or exhaled by the gas jets, leaving the edge with a high-quality finish surface. Industrial laser cutter is used for cutting flat sheet material as well as structural materials and pipes.
Video Laser cutting
Histori
In 1965, the first production laser cutting machine was used to drill a hole in a dead diamond. This machine is made by the Western Electrical Engineering Research Center. In 1967, the British pioneered the cutting of oxygen jets with the help of lasers for metal. In the early 1970s, this technology was put into production for cutting titanium for aerospace applications. At the same time CO 2 lasers were adapted to cut non-metals, such as textiles, because, at that time, the CO 2 lasers were not strong enough to overcome the heat conductivity of metals.
Maps Laser cutting
Process
The generation of laser light involves stimulating the reinforcement material by the release of electricity or lamps in a sealed container. When the reinforcing material is stimulated, the light is reflected internally by using a partial mirror, until it reaches sufficient energy to escape as a monochromatic coherent light stream. Mirrors or optical fibers are commonly used to direct coherent light to the lens, which focuses light on the work zone. The narrowest part of the focused beam is generally less than 0.0125 inches (0.32 mm). in diameter. Depending on the thickness of the material, a streak width as small as 0.004 inches (0.10 mm) is possible. In order to start cutting from a place other than the edge, the piercings are done before each piece. Piercing usually involves a high-powered pulsed laser beam that slowly creates a hole in the material, taking about 5-15 seconds for 0.5-inch (13 mm) stainless steel, for example.
Coherent light parallel rays from laser sources often fall in the range between 0.06-0.08 inches (1.5-2.0 mm) in diameter. These rays are usually focused and intensified by the lens or mirror to a very small point of about 0.001 inches (0.025 mm) to create a very intense laser beam. To achieve the most delicate finish during contour cutting, the direction of the polarization of the rays must be rotated as it rotates around the edges of the contoured workpiece. For sheet metal cutting, the focal length is usually 1.5-3 inches (38-76 mm).
Advantages of laser cutting over mechanical cuts include easier job grinding and reduced workplace contamination (since no cutting edge can be contaminated by material or contaminate material). Precision may be better, because laser light is not used during the process. There is also a reduced possibility of warping the material being cut, because the laser system has a small heat zone. Some materials are also very difficult or impossible to cut in a more traditional way.
Laser cutting for metals has an advantage over cutting plasma to be more precise and uses less energy while cutting sheet metal; However, most industrial lasers can not penetrate the thickness of metals larger than the plasma. Newer laser engines operate at higher power (6000 watts, which is different from the initial '1500 watt' laser cutting machines) approaching plasma engines in their ability to cut thick material, but the capital cost of these machines is much higher than cutting machine plasma capable of cutting thick material such as steel plate.
Type
There are three main types of lasers used in laser cutting. The CO 2 laser is suitable for cutting, drilling, and carving. Neodymium (Nd) and yttrium-aluminum-garnet neodymium (Nd: YAG) lasers are identical in style and differ only in applications. Nd is used for boring and where high energy but low repetition is required. Laser Nd: YAG is used where very high strength is required and for boring and engraving. Both CO 2 and Nd/Nd: YAG lasers can be used for welding.
Common variants of CO 2 lasers include fast axial flow, slow axial flow, transverse flow, and plates.
CO 2 lasers are generally "pumped" by passing the current through a gas mixture (DC-spun) or using radio frequency energy (RF-spun). The RF method is newer and has become more popular. Because DC designs require electrodes in the cavities, they can deal with electrode erosion and coating electrode materials in glass and optics. Because RF resonators have external electrodes, they are not susceptible to such problems.
CO 2 laser is used to cut off many industrial materials including titanium, stainless steel, lightweight steel, aluminum, plastic, wood, engineering wood, wax, fabric, and paper. Laser YAG is mainly used for cutting and cutting metal and ceramic.
In addition to electrical sources, this type of gas flow can affect performance as well. In rapid axial-flow resonators, a mixture of carbon dioxide, helium and nitrogen is circulated at high speeds by a turbine or blower. The transverse flow laser circulates the gas mixture at a lower speed, requiring a simpler blower. Resonator-cooled plates or diffusions have static gas fields that do not require pressure or glass, leading to savings on replacement turbines and glassware.
External laser and optical generators (including focusing lenses) require cooling. Depending on the size and configuration of the system, the wasted heat can be transferred by cooling or directly into the air. Water is a commonly used coolant, usually circulated through a chiller or heat transfer system.
A microjet laser is a jet-guided laser in which a pulsed laser beam is combined into a low-pressure water jet. This is used to perform laser cutting functions when using water jets to guide laser light, such as optical fibers, through total internal reflection. The advantage is that water also removes impurities and cools the material. Additional advantages over traditional "dry" laser cuts are high cutting speeds, parallel scratches, and omnidirectional cuts.
Laser fiber is a type of solid state laser that is growing rapidly in the metal cutting industry. Unlike CO 2 , Fiber technology utilizes a solid strengthening medium, compared to gas or liquid. "Laser seed" produces a laser beam and then reinforced in glass fiber. With a wavelength of only 1,064 micrometers of laser fiber results in a very small place size (up to 100 times smaller than CO 2 ) making it ideal for cutting reflective metal materials. This is one of the main advantages of Fiber compared to CO 2 .
Method
There are many different methods of cutting using lasers, with different types used to cut different materials. Some methods are evaporation, melting and blowing, melting blows and burning, thermal stress cracking, cutting, cold cutting and burning of stable laser cutting.
- Evaporation cuts
- In the evaporation the focused beam heats the surface of the material to its boiling point and generates a keyhole. The keyhole leads to a sudden increase in absorptivity by rapidly deepening the hole. As the hole deepens and the material boils, the resulting vapor erodes the liquid wall that ejects out and enlarges the hole. Non-melting materials such as wood, carbon and thermoset plastics are usually cut by this method.
- Melt and blow
- Melt and blow or fusion cut using high pressure gas to blow liquid from the cutting area, greatly reducing power requirements. First the material is heated to the point of melting, then the jet gas blows the liquid out of the scratches which avoids the need to raise the material temperature further. Materials that are cut with this process are usually metal.
- Thermal stress cracking
- The brittle material is very sensitive to thermal fracture, a feature that is exploited in the thermal crack voltage. The rays are focused on surfaces that cause local heating and thermal expansion. This produces a gap that can then be guided by moving the beam. Cracks can be moved in m/s order. Usually used to cut glass.
- Stealth dicing from silicon wafers
- The separation of microelectronic chips prepared in the fabrication of semiconductor devices from silicon wafers can be accomplished by so-called stealth leaching processes, which operate with well-adopted Nd: YAG, wavelength (1064 nm) lasers. to the silicon electronic band gap (1.11 eV or 1117 nm).
- Reactive cutting
- Also called "burning of stable laser gas cutting", "fire cutting". Reactive cuts such as oxygen torch cutting but with laser light as a source of ignition. Mostly used to cut carbon steel with a thickness of more than 1 mm. This process can be used to cut a very thick steel plate with relatively little laser power.
Tolerance and surface finish
The new laser cutter has a 10 micrometer position accuracy and 5 micrometer repetition.
The standard Rz roughness increases with sheet thickness, but decreases with laser strength and cutting speed. When cutting low carbon steel with 800 W laser power, the standard Rz roughness is 10 m for sheet thickness of 1 mm, 20 m to 3 mm, and 25 m to 6 mm.
Di mana: ketebalan lembaran baja dalam mm; daya laser dalam kW (beberapa pemotong laser baru memiliki kekuatan laser 4 kW); kecepatan potong dalam meter per menit.
This process is able to withstand close tolerance, often up to 0.001 inches (0.025 mm). The geometry of the parts and the mechanical level of the machine have much to do with tolerability. The typical final surface resulting from laser cutting can range from 125 to 250 micro-inches (0.003 mm to 0.006 mm).
Machine configuration
Generally there are three different configurations of industrial laser cutting machines: moving material, hybrid, and fly optical systems. This refers to the way a laser beam is moved over the material to be cut or processed. For all this, the axis of motion is usually designated as the X and Y axes. If the cutting head can be controlled, it is set as the Z axis.
Move laser material has a stationary cutting head and move the material underneath. This method provides a constant distance from the laser generator to the workpiece and a point from which to remove the effluent cut. It requires less optics, but requires moving the workpiece. These style machines tend to have the fewest optical file submissions, but also tend to be slowest.
The hybrid laser provides a moving table in a single axis (usually the X axis) and moves the head along the shorter axis (Y). This results in a more constant ray-shipping path length than a flying optical engine and can allow a simpler ray delivery system. This can lead to reduced power loss in the delivery system and more capacity per watt than the flying optical engine.
The fly optical laser has a stationary table and a cutter head (with a laser beam) that moves over the workpiece in both horizontal dimensions. Flying optical cutters keep the stationary stationary during processing and often do not require material clamping. The moving mass is constant, so the dynamics are not affected by the size of the workpiece. The flying optical engine is the fastest type, which is advantageous when cutting thinner workpieces.
The flying optical engine should use several methods to account for the change of the beam length from the near field (close to the resonator) cut into the far field (away from the resonator) cut off. Common methods of controlling this include collimation, adaptive optics or the use of long-axis constant beams.
five and six axes also enable cutting of the workpiece formed. In addition, there are various methods of laser beam orientation to shaped workpieces, maintaining proper focal distance and deadlock nozzle, etc.
Pulsing
Laser pulsations that provide high-energy explosive power for a short time are very effective in some laser cutting processes, especially for piercing, or when very small holes or very low cutting speeds are required, because if a constant laser beam is used, the heat can reach the melting point of the entire piece the cut.
Most industrial lasers have the ability to pulse or bypass CW (Continuous Wave) under NC program control (numerical control).
The dual pulse laser uses a series of pulse pairs to increase the level of material removal and hole quality. Basically, the first pulse removes the material from the surface and the second prevents the ejecta from sticking to the side of the hole or cutting.
Power consumption
The main disadvantage of laser cutting is high power consumption. The efficiency of industrial lasers can range from 5% to 45%. The power consumption and efficiency of a particular laser will vary depending on the output power and the operating parameters. This will depend on the type of laser and how well the laser is adjusted to the work being done. The amount of laser-cutting power required, known as heat input , for a particular job depends on the type of material, thickness, process (reactive/inert) used, and the desired cutting rate.
Production and Cutting rate
The maximum cutting rate (production rate) is limited by a number of factors including laser power, material thickness, process type (reactive or inert), and material properties. The general industrial system (> = 1 kW) will cut the carbon steel metal from 0.51 - 13 mm in thickness. For all intents and purposes, lasers can reach up to thirty times faster than standard sawmills.
See also
References
Bibliography
- Bromberg, Joan (1991). Laser in America, 1950-1970 . MIT Press. p.Ã, 202. ISBNÃ, 978-0-262-02318-4. Ã,
- Oberg, Erik; Jones, Franklin D.; Horton, Holbrook L.; Ryffel, Henry H. (2004). Machine Handbook (edition 27). New York, NY: Industrial Press Inc. ISBN: 978-0-8311-2700-8.
- Todd, Robert H.; Allen, Dell K.; Alting, Leo (1994). Manufacturing Process Reference Guide . Industrial Press Inc. ISBNÃ, 0-8311-3049-0.
External links
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