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Laser Welding |
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Laser beam welding is increasingly being used in industrial production ranging from microelectronics to shipbuilding. Automotive manufacturing is one of the industrial sectors, which has proven to be most outstanding at developing applications that take advantage of the benefits of this technology:
- Low heat input
- Small heat affected zone (HAZ)
- Low distortion rate
- High welding speed
These characteristics have made laser welding the process of choice for many applications that used resistance welding in the past. By adding the benefits of single-sided access, laser welding is given another strategic advantage, opening the door for a multitude of new applications.
High-power CO2 lasers (2-20 kW) have been used for many years for welding of car bodies, transmission components, tailored blanks, heat exchangers and pipes. Solid state lasers such as diode pumped Nd:YAG lasers, disc lasers and fiber lasers have been scaled up significantly in power over the last years and add the benefit of beam delivery via optical fibers. These are easily manipulated by robots, thereby opening a large field of 3-D applications, such as laser cutting and welding of car bodies.
High-power laser welding is characterized by keyhole welding. The laser energy then melts and evaporates the metal. The pressure of the vapor displaces the molten metal so that a cavity is formed - the keyhole. The keyhole supports the transfer of the laser energy into the metal and guides the laser beam deep into the material. Keyhole welding thus allows very deep and narrow welds to be obtained and is therefore also called deep penetration welding.
Welding gas plays an important role in laser welding and fulfills several tasks - shielding of the weld pool and the heat affected area, protection of the optics against fumes and spatter, root protection and plasma control during CO2 laser welding. The weld plasma is a cloud of ionized metal vapor and gases that can be formed above the keyhole. This cloud affects laser radiation and thus has the potential to interrupt the welding process.
Linde has developed several shielding gas for laser welding which offer performance gains and quality increases: |
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| Laser beam welds are expected to exhibit high quality with high rates of reproducibility and little distortion. For this purpose Linde Gas AG has developed its LASGON® C1 shielding gas, a mixture of helium, argon and carbon dioxide. It is especially suited for the requirements of non-alloy and low-alloy steel, in particular for galvanised sheet metal. The ideal composition of this gas mixture enables the use of relatively high welding speeds without much heat being produced, the result being clean, even and high-quality welding seams. In addition, LASGON® C1 guarantees an increase in the stability of the welding process. This has a positive effect on the cost effectiveness of the process. |
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| LASGON® H is a family of special laser welding process gas, developed for laser welding applications of stainless steel components such as pipes, sensor casings, cabinets and so on. Compared to pure noble gases, LASGON® H allows higher welding speeds and produces less oxide build-up, resulting in a clean, shiny weld surface. |
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