PDF | One of the newest procedures successfully used in machine building Laser Welding claims the laser beam to focus greater energy in a. Laser Beam Welding. The term laser is the abbreviation for,,Light Amplification by Stimulated Emission of Radia- tion”. The laser is the further. Welding (LBW) is a fusion joining process that produces coalescence of materials with welded. In the LBM process, the laser beam is directed by flat optical.
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Types of lasers include gas, liquid and solid. 1. Gas lasers excite the electrons in gases, such as helium, neon, carbon dioxide and nitrogen. 2. In this article you will learn about Laser Beam Welding equipment, principle, working, advantages and disadvantages with its application. A Laser is a device that produces a concentrated coherent light beam by mature laser technology and has been a mainstay of macro laser welding since.
Harinath Gowd G Harinath Gowd et al. LBW process is so complex in nature that the selection of appropriate input parameters is not possible by the trial-and-error method. The selection of welding parameters in any machining process significantly affects the weld quality and the production cost. In this work, the effects of welding input parameters, viz. It is based on the empirical models developed by response surface methodology.
Weld quality tends to be higher as well, since the potential for undercutting is reduced. The first type uses one of several solid media, including synthetic ruby chromium in aluminum oxide , neodymium in glass Nd:glass , and the most common type, neodymium in yttrium aluminum garnet Nd:YAG.
Gas lasers use mixtures of gases such as helium , nitrogen , and carbon dioxide CO2 laser as a medium. Regardless of type, however, when the medium is excited, it emits photons and forms the laser beam. Nd:YAG lasers can operate in both pulsed and continuous mode, but the other types are limited to pulsed mode. This rod is surrounded by a flash tube containing xenon or krypton. When flashed, a pulse of light lasting about two milliseconds is emitted by the laser.
Disk shaped crystals are growing in popularity in the industry, and flashlamps are giving way to diodes due to their high efficiency. To deliver the laser beam to the weld area, fiber optics are usually employed.
Gas laser[ edit ] Gas lasers use high-voltage, low-current power sources to supply the energy needed to excite the gas mixture used as a lasing medium.
These lasers can operate in both continuous and pulsed mode, and the wavelength of the CO2 gas laser beam is Fiber optic cable absorbs and is destroyed by this wavelength, so a rigid lens and mirror delivery system is used.
Laser beam delivery[ edit ] Modern laser beam welding machines can be grouped into two types.
In the traditional type, the laser output is moved to follow the seam. This is usually achieved with a robot. In many modern applications, remote laser beam welding is used. In this method, the laser beam is moved along the seam with the help of a laser scanner , so that the robotic arm does not need to follow the seam any more. The advantages of remote laser welding are the higher speed and the higher precision of the welding process.
Thermal modeling of pulsed-laser welding[ edit ] Pulsed-laser welding has advantages over continuous wave CW laser welding. Some of these advantages are lower porosity and less spatter. Due to the complexity of the pulsed laser process, it is necessary to employ a procedure that involves a development cycle. Mixtures of gases such as nitrogen, helium and co2 are used as lasing medium.
Solid-state laser: it uses several solid media such as synthetic ruby crystal chromium in aluminum oxide , neodymium in glass Nd:glass , and neodymium in yttrium aluminum garnet Nd-YAG , most commonly used.
Fiber laser: The lasing medium in this type of laser is optical fiber itself. Characteristics of Laser Beam Welding The power density of laser beam welding is high. Because of this high energy density, it has small heat-affected zones.
The rate of heating and cooling is high. The laser beams produced are coherent having same phase and monochromatic i. It is used to weld smaller sizes spot but the spot sizes can vary from.
The depth of penetration of the LBW depends upon the amount of power supply and location of the focal point. It is proportional the amount of power supply. When the focal point is kept slightly below the surface of the workpiece, the depth of penetration is maximized. Pulsed or continuous laser beams are used for welding.
Thin materials are weld by using millisecond-pulses and continuous laser beams are used for deep welds. It is versatile process because it is capable of welding carbon steels, stainless steel, HSLA Steels, aluminum and titanium. Due to high cooling rate, the problem of cracking is there when welding high-carbon steels.
It produces high quality weld.
This welding process is most popular in automotive industry. Working First the setup of welding machine at the desired location in between the two metal pieces to be joined is done.
After setup, a high voltage power supply is applied on the laser machine. This starts the flash lamps of the machine and it emits light photons. The energy of the light photon is absorbed by the atoms of ruby crystal and electrons get excited to their higher energy level. When they return back to their ground state lower Energy state they emit a photon of light.
This light photon again stimulates the excited electrons of the atom and produces two photons. This process keeps continue and we get a concentrated laser beam. This high concentrated laser beam is focused to the desired location for the welding of the multiple pieces together.
Lens are used to focus the laser to the area where welding is needed. CAM is used to control the motion of the laser and workpiece table during the welding process.
As the laser beam strikes the cavity between the two metal pieces to be joined, it melts the base metal from both the pieces and fuses them together. After solidification we get a strong weld. This is how a laser Beam Welding Works.
Advantages It produces high weld quality. LBW can be easily automated with robotic machinery for large volume production.
No electrode is required. No tool wears because it is a non-contact process. The time taken for welding thick section is reduced.