carbon dioxide laser
CO2 lasers run electricity through a tube filled with a gas mixture, which creates a beam of light. There are mirrors at each end of the tube. One of the mirrors is fully reflective, and the other is partially reflective, allowing some of the light to pass through. The gas mixture is usually carbon dioxide, nitrogen, hydrogen, and helium. CO2 lasers produce invisible light in the far infrared range of the spectrum.
The highest-power CO2 lasers used in industrial machines are up to a few kilowatts, but these are by far the exception. Typical machining CO2 lasers range from 25 to 100 watts and have a wavelength of 10.6 microns.
This type of laser is most commonly used for processing wood or paper (and its derivatives), PMMA, and other acrylic plastics. It can also be used to treat leather, fabric, wallpaper, and similar products. It is also used in the processing of foods such as cheese, chestnuts, and various plants.
CO2 lasers are generally best for non-metallic materials, although they can process some metals. It can generally cut thin sheet of aluminum and other non-ferrous metals. One can boost the power of a CO2 beam by increasing the oxygen content, but this can be risky for the inexperienced or using machines not suited for this type of boost.
fiber-optic laser
These machines belong to the group of solid-state lasers and use seed lasers. They used specially designed glass fibers that harvest energy from pump diodes to amplify the beam. Their typical wavelength is 1.064 microns, resulting in an extremely small focal diameter. They are also usually the most expensive of various laser-cutting equipment.
Fiber lasers are typically maintenance-free and have a long lifetime of at least 25,000 laser hours. As a result, fiber lasers have a much longer life cycle than the other two types of lasers and can produce strong and stable beams. They can manage 100 times higher intensities than CO2 lasers with the same average power. Fiber lasers can be a continuous beam, quasi-beam, or available in pulsed setups, giving them different capabilities. A subtype of the fiber laser system is the MOPA, where the pulse duration is adjustable. This makes MOPA lasers one of the most flexible lasers available for a wide variety of applications.
Fiber lasers are best suited for metal marking by annealing, metal engraving, and marking thermoplastics. It works on metals, alloys, and similar non-metals, even glass, wood, and plastics. Depending on the power, fiber lasers are versatile and can process a large number of different materials. Fiber lasers are the ideal solution when processing thin materials. However, this is not the case for materials over 20 mm, but more expensive fiber laser machines over 6 kW can solve the problem.
Nd: YAG/Nd: YVO Lasers
Crystal laser cutting processes can use nd: YAG (neodymium-doped yttrium aluminum garnet), but more commonly they tend to use nd: YVO (neodymium-doped yttrium orthovanadate, YVO4) crystals. These devices have extremely high cutting capabilities. The downside of these machines is that they can be expensive, not only because of their initial price but also because they have an expected lifetime of 8,000 to 15,000 hours (Nd: YVO4 typically has a lower lifetime) and the pump diodes can net a very high price.
These lasers offer a wavelength of 1.064 microns and can be used in a wide range of applications from medical and dental to military and manufacturing. Comparing the two Nd: YVO exhibits higher pump absorption and gain, wider bandwidth, wider pump wavelength range, shorter upper-level lifetime, higher refractive index, and lower thermal conductivity Rate. In terms of continuous operation, Nd: YVO has an overall performance level similar to Nd: YAG at medium or high power. However, Nd: YVO does not allow the same high pulse energy and laser lifetime lasing as Nd: YAG
sublimation cutting
With sublimation cutting, the laser beam brings the material directly to its point of vaporization in a process called sublimation. Inert or non-reactive cutting gases such as nitrogen, helium, or argon force the molten material out of the cut piece.
During sublimation cutting, the material changes directly from a solid to a gaseous state with as little melting as possible. Cutting gas keeps particles and vapors away from optics.
It takes more energy to vaporize metal than to melt it. Therefore, sublimation cutting requires a lot of laser power and is usually slow compared to other cutting processes. However, this extra energy provides a very high-quality cut.
Typical materials used in sublimation cutting are wood, plastics, composites, organic glass (PMMA), ceramics, cardboard, paper, foam, and other materials that do not have a melting point. Thin metals can also be cut by sublimation cutting.
Oxy-fuel cutting and oxy-fuel cutting
With oxyfuel cutting (also known as oxy-fuel cutting), the material is only heated to its ignition temperature. Oxygen is used as the cutting gas to burn the material and form a stream of pure oxide, which is melted by the additional energy generated by the combustion. The cutting oxygen then forces the slag out of the cut piece.
Typical materials used for oxyfuel or oxyfuel/oxygen cutting are low alloy steel (also known as mild steel stainless steel or aluminum) and cast iron.
When flame cutting is used, the ignition temperature of the material must be below the melting point. For high-alloy steels and non-ferrous metals, oxy-fuel cutting is feasible, but not ideal for quality and economic reasons.
Melt cutting
In infusion cutting, the material is heated to its melting point by a laser beam and extruded through the incision by a high-pressure cutting gas flow (up to 25 bar). As with sublimation cutting, an inert gas, usually nitrogen, is used to force the molten material out of the cut.
In special cases, argon is the inert gas used. This is the case, for example, with magnesium, tantalum, titanium, and zircon, since these materials form chemical bonds with nitrogen.
Materials not suitable for oxyfuel cutting can be cut using the fusion cutting process. Commonly used materials include alloy steel, also known as stainless steel.
For quality reasons, fusion cutting can also be used to cut unalloyed and low-alloy steels. This produces an oxide-free cut surface but cuts much more slowly.
Whether sublimation cutting, oxyfuel cutting, or fusion cutting is used, due to the narrow focus of the laser beam, the width of the cut, or kerf, is very small compared to other thermal cutting processes. As a result, minimal material is melted and the laser energy is used very efficiently. The heat input to the material is relatively low, so even small geometries can be cut.
Additionally, the cut edges are relatively straight, providing very high part accuracy from the cutting process. This means that laser cutting can be used in the most diverse fields, especially when high precision is required in terms of component geometry and cut edges. The preferred range for steel plates is a material thickness of up to 20 mm. However, in some cases, this range can be extended to 25mm.
For laser cutting, fiber lasers (straight), fiber laser beveling, fiber laser/plasma combinations, and CO2 lasers are commonly used. However, for greater material thicknesses, laser cutting only makes sense in special applications, where other cutting processes (oxy-fuel or plasma cutting) are usually used.