Metal laser cutting is suitable for cutting sheet metal up to 80 mm thick as well as pipes of different cross-sections. Metal laser cutting is actively ousting other cutting methods from the market as the technology is developing rapidly, and the speed of metal laser cutting, the maximum possible cut thicknesses, and the efficiency of metal laser cutting machines are increasing year by year.
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In this article, we will explain the basic operating principles of metal laser cutting machines, what their advantages over other metal cutting technologies are, what metals can be cut and what can be manufactured using metal laser cutting, and how various models of metal laser cutting machines differ.
Modern metal laser cutting machines use a fiber optic laser source as the emitter. The generation process takes place in the pump diodes by means of a resonator, and then the laser beam is fed through an optical fiber to the laser head of the metal laser cutting machine, where a collimator and a focusing lens are located.
The focused laser beam has a high power density due to its monochromaticity and coherence.
Monochromaticity means that the spectrum of wavelengths emitted is so narrow that the photons of laser radiation can be said to have the same or close to the same wavelength.
Coherence refers to the coherence of the wave motions of a laser. Temporal coherence ensures the consistency of oscillations at the same point in space at different times, while spatial coherence ensures that the laser radiation is unidirectional and that the diffraction limit, i.e. the minimum value of the laser beam spot emitted by a metal laser cutting machine, is reached.
It is thanks to this that a metal laser cutter is able to focus to a point 0.01mm in diameter with a power density of 10¹³W or more, which allows the laser radiation to heat metal to a melting point at an area 8 times smaller than a human hair in a fraction of a second.
In pulsed mode, the duration of each individual pulse can be as long as 10‾¹⁵ seconds.Metal laser cutting is divided into two basic methods: fusion cutting and sublimation cutting.
The high power density of the laser beam instantly melts the metal while an auxiliary gas is supplied to the cutting zone, which blows the molten material away and can also cool the area around the cutting zone.
In laser metal cutting, heating occurs locally over a small area around the point of impact, so the material is not overheated or deformed.This method is more commonly used in micro engineering for laser cutting of thin metals. It is very energy intensive as high-powered nanosecond lasers are used to vaporise the material without deformation. The efficiency is 5-8 times lower than in laser fusion cutting of metals.
Laser cutting of metal is one of the youngest, yet most advanced methods of cutting sheet metal and pipes. It has the following advantages:
Laser metal cutting machine. Everything you wanted to know about laser cutting of metals
The following metals are suitable for laser cutting:
If a metal laser cutting machine is equipped with a special unit, it can cut not only sheet metal, but also round and rectangular pipes. There are also specialised machines for laser cutting of metal pipes.
Each type of metal requires a specific auxiliary gas for laser cutting.Air or oxygen is used for laser cutting of ferrous metals. Laser cutting of metal with air requires a compressor, and with this method, you can cut relatively small thicknesses up to 3-5 mm. But with enough laser source power the maximum material thickness can be up to 20 mm. Laser cutting of metal with oxygen makes cutting several times faster.
Inert gases, most commonly nitrogen, are used for the following tasks:
A metal laser cutting machine is not well suited to cut wooden materials. Moreover, it would be an unviable solution, as CO2 machines are ideal for wood-based materials, and they are considerably cheaper than metal laser cutting machines.
For more details on choosing a metal laser cutting machine, contact Virmer managers: +, е-mail: .
Metal laser cutting is used in shipbuilding, aircraft and machine construction, automotive manufacturing, construction, instrumentation, medical and food industries.
What can be manufactured using metal laser cutting machines?
How to choose a fiber metal cutter
The Wattsan metal laser cutting machines on our website can be divided into 3 main categories: E-line, S-line, and HARD-line. The E and S lines are available in working area sizes x mm and x mm, while the HARD-line has sizes x, x, and x mm.
The main difference between the three models is the maximum power of the laser source, the design of the housing, and the components. This, consequently, determines the performance and the maximum possible thickness of the material to be cut.
The thicker the material, the more powerful the laser source is required to cut metal, and the greater the demands on the machine bed and all components.In terms of what these models have in common, the following points can be highlighted:
Now, let us take a closer look at the differences between the Wattsan E-line, S-line, and HARD-line of metal laser cutting machines.
This is the basic model of metal laser cutting machine, and it is more suitable for high-speed laser cutting of thin metal. Features of the E-line:
For more details about such a metal laser cutting machine, see the Wattsan E.
All Wattsan metal laser machine frames undergo an annealing process - a multi-stage heat treatment in a special furnace - to relieve stress on the metal. This ensures warp-free operation for a minimum of 10 years.Wattsan S-line metal laser cutting machines
Designed for high speed and high precision laser cutting of medium thickness metals. Features of the S-line metal laser cutting machines:
For more details, see the Wattsan S.
Wattsan S-line metal laser cutting machines can also be equipped with interchangeable tables, a pipe-cutting unit, and a protective cabin.
The Tablechange saves time by ensuring that while one table is used for laser cutting of a metal sheet, the operator removes the cut pieces and lays out a new sheet of material on the other. The automatic table change takes 18 to 30 seconds.
For example, the Wattsan Tablechange metal laser cutting machine.
It is mounted directly next to the machine. It allows for cutting both sheets of metal and metal pipes. For example, the Wattsan Rotatory metal laser cutting machine.
The Wattsan Rotatory cuts circular pipes up to 220 mm and rectangular pipes up to 160 mm with a length from 3 to 9 metres. Permissible dimensions for laser sheet metal cutting: x mm.
It is designed for safety when using medium and high power laser sources. Completely encloses the working area of a metal laser cutting machine and has viewing windows to protect against reflected laser beams and sparks.
Optional accessories can be combined with each other or fitted all at once, as on the Wattsan Tablechange Rotatory Cabine laser metalworking machine.
Designed for cutting particularly thick metals. Equipped by default with interchangeable tables because this type of laser metal cutting machine initially involves a large workload. Features of the HARD-line:
What is a CNC CO2 laser and how does it work?
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Since we are writing about metal laser cutting, we cannot fail to mention that some CO2 machines are also suitable for this purpose. For example, the Wattsan NC-, which can also cut non-metallic materials.
The laser tube power of this machine is 130-150 W and the size of the working area: x mm. This versatile machine cuts metals up to 1,5 mm thick as well as any other standard materials for CO2 lasers: plywood, veneer, MDF, wood, plastics, textiles, leather, and fur.
Read more about the Wattsan NC- metal laser cutting machine on our website.
A metal laser cutting machine is the most productive tool for cutting sheet metal and pipes. The price of any metal laser cutter depends on the power of the emitter and a number of other parameters.
Laser cutting is a technology that uses a laser to vaporize materials, resulting in a cut edge. While typically used for industrial manufacturing applications, it is now used by schools, small businesses, architecture, and hobbyists. Laser cutting works by directing the output of a high-power laser most commonly through optics. The laser optics and CNC (computer numerical control) are used to direct the laser beam to the material. A commercial laser for cutting materials uses a motion control system to follow a CNC or G-code of the pattern to be cut onto the material. The focused laser beam is directed at the material, which then either melts, burns, vaporizes away, or is blown away by a jet of gas,[1] leaving an edge with a high-quality surface finish.[2]
In , the first production laser cutting machine was used to drill holes in diamond dies. This machine was made by the Western Electric Engineering Research Center.[3] In , the British pioneered laser-assisted oxygen jet cutting for metals.[4] In the early s, this technology was put into production to cut titanium for aerospace applications. At the same time, CO2 lasers were adapted to cut non-metals, such as textiles, because, at the time, CO2 lasers were not powerful enough to overcome the thermal conductivity of metals.[5]
The laser beam is generally focused using a high-quality lens on the work zone. The quality of the beam has a direct impact on the focused spot size. The narrowest part of the focused beam is generally less than 0. inches (0.32 mm) in diameter. Depending upon the material thickness, kerf widths as small as 0.004 inches (0.10 mm) are possible.[6] In order to be able to start cutting from somewhere other than the edge, a pierce is done before every cut. Piercing usually involves a high-power pulsed laser beam which slowly makes a hole in the material, taking around 5–15 seconds for 0.5-inch-thick (13 mm) stainless steel, for example.
The parallel rays of coherent light from the laser source often fall in the range between 0.06–0.08 inches (1.5–2.0 mm) in diameter. This beam is normally focused and intensified by a lens or a mirror to a very small spot of about 0.001 inches (0.025 mm) to create a very intense laser beam. In order to achieve the smoothest possible finish during contour cutting, the direction of the beam polarization must be rotated as it goes around the periphery of a contoured workpiece. For sheet metal cutting, the focal length is usually 1.5–3 inches (38–76 mm).[7][8]
Advantages of laser cutting over mechanical cutting include easier work holding and reduced contamination of workpiece (since there is no cutting edge which can become contaminated by the material or contaminate the material). Precision may be better since the laser beam does not wear during the process. There is also a reduced chance of warping the material that is being cut, as laser systems have a small heat-affected zone.[9] Some materials are also very difficult or impossible to cut by more traditional means.[10]
Laser cutting for metals has the advantage over plasma cutting of being more precise[11] and using less energy when cutting sheet metal; however, most industrial lasers cannot cut through the greater metal thickness that plasma can. Newer laser machines operating at higher power ( watts, as contrasted with early laser cutting machines' -watt ratings) are approaching plasma machines in their ability to cut through thick materials, but the capital cost of such machines is much higher than that of plasma cutting machines capable of cutting thick materials like steel plate.[12]
There are three main types of lasers used in laser cutting. The CO2 laser is suited for cutting, boring, and engraving. The neodymium (Nd) and neodymium yttrium-aluminium-garnet (Nd:YAG) lasers are identical in style and differ only in the application. Nd is used for boring and where high energy but low repetition are required. The Nd:YAG laser is used where very high power is needed and for boring and engraving. Both CO2 and Nd/Nd:YAG lasers can be used for welding.[13]
CO2 lasers are commonly "pumped" by passing a current through the gas mix (DC-excited) or using radio frequency energy (RF-excited). The RF method is newer and has become more popular. Since DC designs require electrodes inside the cavity, they can encounter electrode erosion and plating of electrode material on glassware and optics. Since RF resonators have external electrodes they are not prone to those problems. CO2 lasers are used for the industrial cutting of many materials including titanium, stainless steel, mild steel, aluminium, plastic, wood, engineered wood, wax, fabrics, and paper. YAG lasers are primarily used for cutting and scribing metals and ceramics.
In addition to the power source, the type of gas flow can affect performance as well. Common variants of CO2 lasers include fast axial flow, slow axial flow, transverse flow, and slab. In a fast axial flow resonator, the mixture of carbon dioxide, helium, and nitrogen is circulated at high velocity by a turbine or blower. Transverse flow lasers circulate the gas mix at a lower velocity, requiring a simpler blower. Slab or diffusion-cooled resonators have a static gas field that requires no pressurization or glassware, leading to savings on replacement turbines and glassware.
The laser generator and external optics (including the focus lens) require cooling. Depending on system size and configuration, waste heat may be transferred by a coolant or directly to air. Water is a commonly used coolant, usually circulated through a chiller or heat transfer system.
A laser microjet is a water-jet-guided laser in which a pulsed laser beam is coupled into a low-pressure water jet. This is used to perform laser cutting functions while using the water jet to guide the laser beam, much like an optical fiber, through total internal reflection. The advantages of this are that the water also removes debris and cools the material. Additional advantages over traditional "dry" laser cutting are high dicing speeds, parallel kerf, and omnidirectional cutting.[14]
Fiber lasers are a type of solid-state laser that is rapidly growing within the metal cutting industry. Unlike CO2, Fiber technology utilizes a solid gain medium, as opposed to a gas or liquid. The “seed laser” produces the laser beam and is then amplified within a glass fiber. With a wavelength of only nanometers fiber lasers produce an extremely small spot size (up to 100 times smaller compared to the CO2) making it ideal for cutting reflective metal material. This is one of the main advantages of Fiber compared to CO2.
Fibre laser cutter benefits include:
There are many different methods of cutting using lasers, with different types used to cut different materials. Some of the methods are vaporization, melt and blow, melt blow and burn, thermal stress cracking, scribing, cold cutting, and burning stabilized laser cutting.
In vaporization cutting, the focused beam heats the surface of the material to a flashpoint and generates a keyhole. The keyhole leads to a sudden increase in absorptivity quickly deepening the hole. As the hole deepens and the material boils, vapor generated erodes the molten walls blowing ejection out and further enlarging the hole. Nonmelting materials such as wood, carbon, and thermoset plastics are usually cut by this method.
Melt and blow or fusion cutting uses high-pressure gas to blow molten material from the cutting area, greatly decreasing the power requirement. First, the material is heated to melting point then a gas jet blows the molten material out of the kerf avoiding the need to raise the temperature of the material any further. Materials cut with this process are usually metals.
Brittle materials are particularly sensitive to thermal fracture, a feature exploited in thermal stress cracking. A beam is focused on the surface causing localized heating and thermal expansion. This results in a crack that can then be guided by moving the beam. The crack can be moved in order of m/s. It is usually used in the cutting of glass.
The separation of microelectronic chips as prepared in semiconductor device fabrication from silicon wafers may be performed by the so-called stealth dicing process, which operates with a pulsed Nd:YAG laser, the wavelength of which ( nm) is well adapted to the electronic band gap of silicon (1.11 eV or nm).
Reactive cutting is also called "burning stabilized laser gas cutting" and "flame cutting". Reactive cutting is like oxygen torch cutting but with a laser beam as the ignition source. Mostly used for cutting carbon steel in thicknesses over 1 mm. This process can be used to cut very thick steel plates with relatively little laser power.
Laser cutters have a positioning accuracy of 10 micrometers and repeatability of 5 micrometers.[citation needed]
Standard roughness Rz increases with the sheet thickness, but decreases with laser power and cutting speed. When cutting low carbon steel with laser power of 800 W, standard roughness Rz is 10 μm for sheet thickness of 1 mm, 20 μm for 3 mm, and 25 μm for 6 mm.
R z = 12.528 ⋅ S 0.542 P 0.528 ⋅ V 0.322 {\displaystyle Rz={\frac {12.528\cdot S^{0.542}}{P^{0.528}\cdot V^{0.322}}}}
Where: S = {\displaystyle S=} steel sheet thickness in mm; P = {\displaystyle P=} laser power in kW (some new laser cutters have laser power of 4 kW); V = {\displaystyle V=} cutting speed in meters per minute.[16]
This process is capable of holding quite close tolerances, often to within 0.001 inch (0.025 mm). Part geometry and the mechanical soundness of the machine have much to do with tolerance capabilities. The typical surface finish resulting from laser beam cutting may range from 125 to 250 micro-inches (0.003 mm to 0.006 mm).[13]
There are generally three different configurations of industrial laser cutting machines: moving material, hybrid, and flying optics systems. These refer to the way that the laser beam is moved over the material to be cut or processed. For all of these, the axes of motion are typically designated X and Y axis. If the cutting head may be controlled, it is designated as the Z-axis.
Moving material lasers have a stationary cutting head and move the material under it. This method provides a constant distance from the laser generator to the workpiece and a single point from which to remove cutting effluent. It requires fewer optics but requires moving the workpiece. This style of machine tends to have the fewest beam delivery optics but also tends to be the slowest.
Hybrid lasers provide a table that moves in one axis (usually the X-axis) and moves the head along the shorter (Y) axis. This results in a more constant beam delivery path length than a flying optic machine and may permit a simpler beam delivery system. This can result in reduced power loss in the delivery system and more capacity per watt than flying optics machines.
Flying optics lasers feature a stationary table and a cutting head (with a laser beam) that moves over the workpiece in both of the horizontal dimensions. Flying optics cutters keep the workpiece stationary during processing and often do not require material clamping. The moving mass is constant, so dynamics are not affected by varying the size of the workpiece. Flying optics machines are the fastest type, which is advantageous when cutting thinner workpieces.[17]
Flying optic machines must use some method to take into account the changing beam length from the near field (close to the resonator) cutting to the far field (far away from the resonator) cutting. Common methods for controlling this include collimation, adaptive optics, or the use of a constant beam length axis.
Five and six-axis machines also permit cutting formed workpieces. In addition, there are various methods of orienting the laser beam to a shaped workpiece, maintaining a proper focus distance and nozzle standoff.
Pulsed lasers which provide a high-power burst of energy for a short period are very effective in some laser cutting processes, particularly for piercing, or when very small holes or very low cutting speeds are required, since if a constant laser beam were used, the heat could reach the point of melting the whole piece being cut.
Most industrial lasers have the ability to pulse or cut CW (continuous wave) under NC (numerical control) program control.
Double pulse lasers use a series of pulse pairs to improve material removal rate and hole quality. Essentially, the first pulse removes material from the surface and the second prevents the ejecta from adhering to the side of the hole or cut.[18]
The main disadvantage of laser cutting is the high power consumption. Industrial laser efficiency may range from 5% to 45%.[19] The power consumption and efficiency of any particular laser will vary depending on output power and operating parameters. This will depend on the type of laser and how well the laser is matched to the work at hand. The amount of laser cutting power required, known as heat input, for a particular job depends on the material type, thickness, process (reactive/inert) used, and desired cutting rate.
Amount of heat input required for various materials at various thicknesses using a CO2 laser [watts][20] Material Material thickness 0.51 mm 1.0 mm 2.0 mm 3.2 mm 6.4 mm Stainless steel Aluminium Mild steel − 400 − 500 − Titanium 250 210 210 − − Plywood − − − − 650 Boron/epoxy − − − −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. Common industrial systems (≥1 kW) will cut carbon steel metal from 0.51 – 13 mm in thickness. For many purposes, a laser can be up to thirty times faster than standard sawing.[21]
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Cutting rates using a CO2 laser [cm/second] Workpiece material Material thickness 0.51 mm 1.0 mm 2.0 mm 3.2 mm 6.4 mm 13 mm Stainless steel 42.3 23.28 13.76 7.83 3.4 0.76 Aluminium 33.87 14.82 6.35 4.23 1.69 1.27 Mild steel − 8.89 7.83 6.35 4.23 2.1 Titanium 12.7 12.7 4.23 3.4 2.5 1.7 Plywood − − − − 7.62 1.9 Boron / epoxy − − − 2.5 2.5 1.1