This is done through either vaporization, melting, chemical ablation, or controlled crack propagation. The laser optics is digitally controlled by a CNC Computer Numerical Control making the process suitable for drilling holes as small as 5 microns.
Moreover, the process does not produce residual stresses on the material allowing the cutting of fragile and brittle materials. Laser drilling is a type of laser machining process that is done by several methods, including single-shot drilling, percussion drilling, trepanning, and helical drilling. Single-shot and percussion laser drilling produce holes at a higher rate than the other two processes.
Trepanning and helical drilling, on the other hand, produce more accurate, higher quality holes. Aside from the accuracy of the process, there are other advantages offered by laser cutting. Since there are no cutting tools used, the non-contact nature of lasers produces no tool wear issues.
High strength, brittle materials such as diamond tools and refractory ceramics. The first production laser cutting was introduced in and was used to drill holes in diamond dies. Laser cutting technology was then used for cutting high strength alloys and metals such as titanium for aerospace applications.
Its range of applications also covers the cutting of polymers, semiconductors, gems, and other metallic alloys. Laser stands for "light amplification by stimulated emission of radiation". Aside from the cutting applications of lasers, they can also be used for joining, heat treating, inspection, and free form manufacturing. Lasers used for laser cutting differ from other machining processes since it requires higher power densities but with shorter interaction times.
Lasers are produced by generating light from a high-intensity light source inside a reflective laser cavity. The laser cavity contains a laser rod where the radiation is generated. The light source is used to stimulate the laser rod which is composed of atoms of a lasing media that absorbs certain wavelengths of light from the light source. From physics, it is known that light is composed of small bundles of energy called photons.
As photons strike the atoms of the lasing media, the atoms become energized. When another photon strikes the energized atom, the atom gives off two more photons with the same wavelength, direction, and phase.
This is called stimulated emission. The new photons further stimulate other energized atoms producing more photons, causing a cascade of excitations. Two parallel mirrors are located on both ends of the laser rod. Photons moving perpendicular to these mirrors stay within the laser rod. One mirror is partially transmissive, enabling the partial escape of light from the cavity.
This escaping stream of coherent, monochromatic light is the laser beam used to cut the material. Another set of mirrors or fiber-optics direct light into a lens. This lens focuses the light into the material. There are three main types of lasers used for cutting. They differ on the base material used to generate the laser beam. Instead of light, laser pumping is done by discharging an electrical current. When the electrical discharge passes through the lasing medium, nitrogen molecules become excited, bringing it to a higher energy level.
Unlike what was described before, these excited nitrogen molecules do not lose their energy by photon emission. Rather, it transfers its vibrational mode energy to CO2 molecules.
This process goes on continuously until most of the CO2 molecules are at the metastable state. The CO2 molecules then emit infrared light at either The resonating mirrors are designed to reflect the emitted photons on those wavelengths. One mirror is a partially reflecting mirror allowing the release of the infrared beam that is used for cutting the material. After releasing infrared light, the CO2 molecules then return to the ground state by transferring its remaining energy to the doped helium atoms.
The cold helium atoms then become hot which is cooled by the cooling system of the laser. Unlike the CO2 laser, this type is a solid-state laser that uses a synthetic crystal as a lasing medium. In this crystal, the Nd ions replace the Y ions in the crystal structure.
The length of the rod is about 10 cm with a diameter of 6 to 9 cm. The ends of the YAG rod is polished and coated by highly reflective materials acting as the resonator system.
Laser pumping is achieved by krypton flashlamps or laser diodes. This laser pumping excites the Nd ions into higher energy levels. After a short while, the excited Nd ions move into a lower, more stable state, without emitting photons. This process goes on until the medium is populated with excited Nd ions. From its metastable state, the Nd ions release infrared light with a wavelength of nm.
Fiber-optic lasers are one of the newer types which use fiber-optics as the lasing medium instead of gases CO2 lasers and crystals Nd-YAG lasers.
Since it uses fiber-optics, fiber lasers are solid-state lasers that operate the same way as crystal lasers. Normal, CW laser cutting is thermal, i. I agree that this answer is misleading. Show 8 more comments. Add a comment. Michael Durrant Michael Durrant 1 1 silver badge 6 6 bronze badges. Lissandro Lissandro 31 2 2 bronze badges.
But if the extra forces incurred by them marching in unison is enough to break the bridge, it probably wasn't the best idea to be crossing it at all. Nikos M. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.
Email Required, but never shown. Featured on Meta. Now live: A fully responsive profile. Linked Related Hot Network Questions. Question feed. Physics Stack Exchange works best with JavaScript enabled. Some types of metal , like copper alloys and certain aluminium grades are too reflective for CO2 lasers. This is a limitation that hampers different use-cases.
The first fibre lasers were introduced in at EuroBlech. The different laser beam conveying methods allowed cutting highly reflective metals.
Now, metals like aluminium, brass, copper and galvanised steel are available for laser cutting. Fibre lasers are simpler and more durable. The laser light is first created by banks of diodes. It is then channelled through optic cables, where it gets amplified.
The cables are doped with rare earth elements like erbium, thulium and the like. These elements are used for amplifying the light. Finally, the lens focuses the light to form a laser beam ready for cutting. The new system needs no gases, mirror realignments, nor warming up. A big advantage of fibre lasers is its high energy conversion rate. The significant difference comes mainly from the low losses in heat generation.
This makes 2 kW fibre lasers comparable to more high power CO2 counterparts. The major improvements spur on engineers to continue developing this revolutionary technology. This is an indication for the future. Although the majority of the market is still in the grasp of CO2 lasers, fibre lasers are catching up. Now, an increasingly large share of new sales is reserved for the latter. The maintenance costs of fibre lasers is a big selling point. There are fewer moving parts and less adjustments to make.
That results in lower down-times due to maintenance. Today, the fibre laser is significantly quicker when cutting thin metals. CO2 still beats fibre when cutting thicker materials 10 mm and more with its better edge quality. Altogether, the future seems bright for fibre lasers.
In flame cutting, oxygen is used as the assist gas. In addition to exerting mechanical force on the molten material, this creates an exothermic reaction which increases the energy input to the process.
In remote cutting, the material is partially evaporated ablated by a high-intensity laser beam, allowing thin sheets to be cut with no assist gas. Improvements in accuracy, edge squareness and heat input control means that the laser process is increasingly replacing other profiling cutting techniques, such as plasma and oxy-fuel.
There are many state of the art laser machines on the market for cutting purposes, which can be used to cut metals, woods and engineered woods. The laser cutting process involves focusing a laser beam, usually with a lens sometimes with a concave mirror , to a small spot which has sufficient power density to produce a laser cut. The lens is defined by its focal length, which is the distance from the lens to the focused spot.
The critical factors which govern the efficiency of the process are the focused spot diameter d and the depth of focus L. The depth of focus is the effective distance over which satisfactory cutting can be achieved. The laser focal spot diameter and the depth of focus is dependent on the raw laser beam diameter on the lens and the focal length of the lens. For a constant raw laser beam diameter, decrease in the focal length lens of the focusing lens results in a smaller focal spot diameter and depth of focus.
For a constant focus length lens, increase in the raw beam diameter also reduces both the spot diameter and the depth of focus. To allow comparison between lasers with different beam diameters we therefore use a factor called the focus f-number, which is the focal length, F, divided by the incoming raw beam diameter, D.
Because these two requirements are in conflict with each other, a compromise must be made. The only other consideration is that the shorter the focal length, the closer the lens is to the workpiece, and therefore more likely to get damaged by spatter from the cutting process. In fact, it would be possible to optimise focal length for each material thickness, but this would involve additional set-up time when changing from one job to another, which would have to be balanced against the increased speed.
In reality, changing the lens is avoided and a compromised cutting speed used, unless a specific job has special requirements. Nowadays most of industrial sheet metal laser cutting is carried out using two types of lasers: CO 2 and fibre. The CO 2 laser carbon dioxide laser is generated in a gas mixture, which mostly consists of carbon dioxide CO 2 , helium and nitrogen. Such a laser is electrically pumped using an electric discharge.
CO 2 lasers typically emit at a wavelength of Those used for material processing can generate beams of many kilowatts in power. It also produces a smoother surface finish when cutting thicker materials.
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