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Technologies
WHAT IS A LASERS
LASER CUTTING
What is a Lasers? The word Laser is an acronym and stands for "Light Amplification by Stimulated Emission of Radiation". A Laser light source has a number of main properties, namely it is "Coherent, Monochromatic, Collimated, and very Bright or highly Brilliant". These key properties allow laser light to find application in a whole host of different fields, from measuring distances to within a thousandth of a unit and cutting or welding applications involving various materials – organic included – to use in the telecommunications industry with the aid of even very long optical fibres. Radiation is a phenomenon whereby energy is transported through space. The type of radiation we are most familiar with comes from the sun or in the shape of heat that can be felt when light is reflected off what might be an apparently unreflective material. There is always a form of Energy associated with radiation and, in the case of lasers, it is associated with the emission of photons. A typical phenomenon is the propagation of electromagnetic waves through empty space, whose velocity is 299,792 km/sec.This value is indicated in formulas with the letter "c" and is the speed at which energy is transmitted in a vacuum, while "λ" (lambda) stands for the wavelength and "f" for frequency. The frequency is thus related to "c" and "λ" with the following formula f = c / λ; said relation is always valid since "c" is a constant. Light refers to electromagnetic radiation with a range of wavelength from 380 nm for violet to approx. 769 nm for red, associated with the propagation of photons, in other words a mass.
CO2 laser (Carbon Dioxide). Wavelength λ = 10.6 nm
As we know, CO2 Laser light is produced by Carbon Dioxide. When subjected to an electromagnetic field, this gas emits photons as the electrons that orbit around the molecule's nucleus become excited. The Resonator, or Laser machine, inside which the Laser phenomenon is produced, usually consists of a glass tube known as the "Cavity" inside which the gas flows; gas flow is induced by a turbine or booster. The gas is actually a gas mixture, usually made up of He (Helium), N2 (Nitrogen) and only a small percentage of C02 (Carbon Dioxide). It is the CO2 that produces the laser effect when subjected to a magnetic field. The magnetic field can be generated by a series of electrodes (Anodes and Cathodes) located inside the Cavity. In this case, the Resonator is called a Direct Current (DC) model, i.e. the electrical discharge between the Anode and Cathode is produced by a DC power supply. Generators from Convergent (Prima Industrie Group) or from Bystronic are typical generators operating with said systems. Instead of the so-called "DC" system, there is also a Radiofrequency system, in which case the Carbon Dioxide molecule is excited by means of a magnetic field outside the Cavity. Rofin, Trumpf and Fanuc are typical RF generators. It would take endless dissertations to fully cover the technical differences between the various systems, but what they essentially boil down to is this. Laser sources produced with RF systems are infinitely more complex and efficiency ranges from 3% to 6%, in other words it takes at least 15 to 30 kW of electricity to generate 1 kW of Laser power. The DC-excited Laser sources have higher efficiency overall, namely in the range from 5% to 8%. In addition, they are simpler in construction though, since the Anode and Cathode are inside the Cavity, their wear over time causes their operation to deteriorate, resulting in a decrease in resonator efficiency as part of the cathode's and anode's worn material builds up on the surface of the mirrors inside the actual cavity, diminishing the reflective effect. On the other hand, the higher the power, the more difficult it becomes to develop DC sources.
YAG laser wavelength λ = 1.02 1.08 nm wavelength λ = 1.02 1.08 nm
YAG lasers were introduced onto the industrial applications market a decade or so ago. In the cutting field, in particular, it immediately became apparent that they could not compare with CO2 due to the enormous operating costs and application difficulties. The latest newcomer to industrial metal cutting and welding applications using YAG technology is the Fibre Laser. It is produced by IPG, a leading manufacturer of low-power laser sources for the telecommunications industry, originally established in Russia. This new technology is catching on thanks to its undisputed advantages compared to CO2 technology. The generator essentially consists of a diode that can emit a beam of coherent light capable of exciting the ytterbium molecule contained in the active fibre (glass fibre). High-power laser sources can be obtained by grouping together banks of diodes, and hence active fibres, and then connecting them together, with power levels even exceeding those used in CO2 lasers to date. The first undisputed advantage lies in the overall efficiency of the source, which is calculated to be between 25% and 28%, in other words the resonator would have to have a 4 kW power supply to produce 1 kW of Laser energy. Compared with CO2 lasers, total efficiency is approx. 4-5 times higher. The second, equally important advantage lies in the simple and infinitely less complex construction compared to a CO2 laser: there is no Cavity and thus none of the ensuing components; there is no Lasing Gas and thus none of the associated consumption; there is no Turbine; they are smaller; and there is the possibility of having a fibre for transmitting the beam instead of an optical train inside the cutting machine. In addition to marking a turning point in cutting and welding applications, the advent of this new technology on the market also provided a new system for tackling problems associated with the world of cutting and welding machinery.
CO2 laser (Carbon Dioxide). Wavelength λ = 10.6 nm
As we know, CO2 Laser light is produced by Carbon Dioxide. When subjected to an electromagnetic field, this gas emits photons as the electrons that orbit around the molecule's nucleus become excited. The Resonator, or Laser machine, inside which the Laser phenomenon is produced, usually consists of a glass tube known as the "Cavity" inside which the gas flows; gas flow is induced by a turbine or booster. The gas is actually a gas mixture, usually made up of He (Helium), N2 (Nitrogen) and only a small percentage of C02 (Carbon Dioxide). It is the CO2 that produces the laser effect when subjected to a magnetic field. The magnetic field can be generated by a series of electrodes (Anodes and Cathodes) located inside the Cavity. In this case, the Resonator is called a Direct Current (DC) model, i.e. the electrical discharge between the Anode and Cathode is produced by a DC power supply. Generators from Convergent (Prima Industrie Group) or from Bystronic are typical generators operating with said systems. Instead of the so-called "DC" system, there is also a Radiofrequency system, in which case the Carbon Dioxide molecule is excited by means of a magnetic field outside the Cavity. Rofin, Trumpf and Fanuc are typical RF generators. It would take endless dissertations to fully cover the technical differences between the various systems, but what they essentially boil down to is this. Laser sources produced with RF systems are infinitely more complex and efficiency ranges from 3% to 6%, in other words it takes at least 15 to 30 kW of electricity to generate 1 kW of Laser power. The DC-excited Laser sources have higher efficiency overall, namely in the range from 5% to 8%. In addition, they are simpler in construction though, since the Anode and Cathode are inside the Cavity, their wear over time causes their operation to deteriorate, resulting in a decrease in resonator efficiency as part of the cathode's and anode's worn material builds up on the surface of the mirrors inside the actual cavity, diminishing the reflective effect. On the other hand, the higher the power, the more difficult it becomes to develop DC sources.
YAG laser wavelength λ = 1.02 1.08 nm wavelength λ = 1.02 1.08 nm
YAG lasers were introduced onto the industrial applications market a decade or so ago. In the cutting field, in particular, it immediately became apparent that they could not compare with CO2 due to the enormous operating costs and application difficulties. The latest newcomer to industrial metal cutting and welding applications using YAG technology is the Fibre Laser. It is produced by IPG, a leading manufacturer of low-power laser sources for the telecommunications industry, originally established in Russia. This new technology is catching on thanks to its undisputed advantages compared to CO2 technology. The generator essentially consists of a diode that can emit a beam of coherent light capable of exciting the ytterbium molecule contained in the active fibre (glass fibre). High-power laser sources can be obtained by grouping together banks of diodes, and hence active fibres, and then connecting them together, with power levels even exceeding those used in CO2 lasers to date. The first undisputed advantage lies in the overall efficiency of the source, which is calculated to be between 25% and 28%, in other words the resonator would have to have a 4 kW power supply to produce 1 kW of Laser energy. Compared with CO2 lasers, total efficiency is approx. 4-5 times higher. The second, equally important advantage lies in the simple and infinitely less complex construction compared to a CO2 laser: there is no Cavity and thus none of the ensuing components; there is no Lasing Gas and thus none of the associated consumption; there is no Turbine; they are smaller; and there is the possibility of having a fibre for transmitting the beam instead of an optical train inside the cutting machine. In addition to marking a turning point in cutting and welding applications, the advent of this new technology on the market also provided a new system for tackling problems associated with the world of cutting and welding machinery.