Present in the highly competitive automotive market has urgent need for speed. From the consumer side, they are more concerned about horsepower. However, in manufacturing, speed is all the production and productivity. U.S. car manufacturers due to numerous reasons, including the body design and perceived quality as well cost of ownership, is gradually losing its market share. Although the discussion on the body design is not considered in the context of this article, however, the strategy to improve quality and productivity is the focus of discussion. Both can be achieved by mixing processing technology, the technology of laser welding and conventional gas shielded welding wire to weld together.

Laser parameters, such as wavelength, beam quality, spot size, power density, depth of focus, and beam positioning, etc., for the successful welding is crucial. Other parameters also include additional conventional GMAW power source and pulse transmission, GMAW wire position, the contact angle, and chemical properties of the metal lines.

In addition, the base material oxide surface conditions, docking at the design, welding electrodes , and shielding gas type and flow rate also hybrid welding process had an impact on the quality and performance. The following will detail the choice of many aspects of the gas impact of these aspects include the interaction of the laser beam, protection efficiency, bead performance, and used to transmit standard gas mixtures and flow equipment.

Hybrid laser processing technology into a two energy weld pool area. Hybrid laser welding processing technology makes specific advantages, these advantages include improved the speed of welding, heat affected zone is restricted, narrow weld seams also has excellent weld appearance. GMAW as a secondary energy, which improves the overall process energy efficiency, reduce equipment costs while also improving the capacity of the welding gap, in addition, it reduces the cooling rate, while improving the energy coupling efficiency of aluminum. Second, while more complex devices, but by reducing the need for welding the cavity size, GMAW cost of supply can be reduced, thereby reducing the cost of the machine. According to the results of the GMAW wire feed can determine the location before or after the laser beam. GMAW using tail-like wire feed welding methods can achieve higher speed. GMAW wire is welded into the laser generated melt pool, so the need to join the melting wire secondary energy is reduced. In addition, when the filler wire to reach the end of time, GMAW arc produced plasma, evaporation of the substrate material, resulting in the front edge of the weld pool produced a depression. In the molten weld pool depression reduces the laser beam must penetrate the total depth, thus improving the penetration performance. Information has proved very good, or the welding area from the key hole exhaust steam particles will lead to the attenuation of the laser beam (scattering and absorption), thus reducing the coupling with the substrate material beam energy.

1, the scattering and absorption of the laser beam reduces the speed and depth of the welding.

2, layer determines the particle the greater the attenuation effect of the more serious. Helium shielding gas to bring the smallest average particle size of steam. This shows that CO2 or YAG laser welding on it, pure helium is the best choice for control of particle size.

We have to admit, compared to helium and argon, does have a relatively high ionization rate and the formation of low-voltage plasma, but its smaller molecular weight. Therefore, a large helium shielding gas flow rate needed to ensure the effective path of the laser beam on a metal vapor discharge. Since the unit cost of helium than argon, so the welding process which increases the average cost per foot. To optimize the protective gas in order to achieve inhibition of plasma, emit vapor particles, and reduce unit costs, we consider the use of up to 40-50% argon gas mixture. The higher proportion of mixed gas are needed to discharge the steam flow rate of the smaller particles. Mixed gas welding pool is also provided in the curing process longer an inert atmosphere, so that the welding speed even more. It also reduces the amount of captured gas, thereby reducing the porosity brought scrap. Second, the cure rate decreased for the grain growth and to reduce internal stress, which increases the fatigue strength. As the aspect ratio (weld depth / width) and subsequent high stress generated by welding cracks are almost cleared, and this is because the addition of GMAW filler metal resulted in solder width increases. In the mixed gas, should add a small amount of carbon dioxide and / or oxygen, or to process them as secondary GMAW shielding gas, welding beads can be further improved performance. He - Ar mixed gas are prone to a higher arc voltage, the corresponding received wider bead shape, arc stability is higher. Thus, 3-10% carbon dioxide can be added to stabilize the transmission and contraction of the arc. In some cases, you can add 1-5% oxygen to achieve high quality arc stability, while the weld edge for better connection (wet). Compared with carbon dioxide gas mixture, oxygen ionization rate as low thermal conductivity higher performance, easy-to provide broad distribution of light penetration. Quality and productivity standards for the desired gas mixture is finally settled, also need to consider how the delivery of their economies to the point of use. Users can mix the protection of the scene in the production of gas, the use of low-cost mode of supply of liquid argon. Why not pay the price of premixed high-pressure helium gas cylinder to pay for argon, carbon dioxide or oxygen it? Argon through the liquid argon bottle to the delivery of economic and meet the monthly consumption of up to 35,000 cubic feet, equivalent to the amount of the monthly amount of 87,500 cubic feet of gas mixture. The monthly consumption of argon gas, then you can use larger quantities of supply to achieve optimal cost level. Analysis also need to consider filling losses, the monthly equipment costs, bulk supply contract restrictions, and freight and other factors. On the other hand, helium is usually by high-pressure Tube Trailer or cylinder group to supply. Need for a hybrid mix of on-site system, which can accurately adjust from 0-100% of the minor component. Total quality system can be placed in the mixer's exports to achieve a Analyzer monitoring, once the mixture out of range of error, it will alarm. Software and alarm systems have this information can be transmitted to the desktop computer, or by fax or e-mail sent further afield. Rational design of hybrid laser gas delivery system enables users to achieve higher welding speed, corresponding to a higher productivity. Concerned about the protection of the gas parameters, such as type, traffic, and impact angle, to improve the welding quality, reduce beam absorption and scattering effects. Supporting the continuous development of welding technology(Welding Consumable ), some methods such as GMAW and laser technology, allowing users to play the advantages of both technologies, and benefit from it.

Keywords: Brazing Alloy