Progressive laser gas welding technology
In the field of laser gas shielded welding, a unique combination of technologies has emerged. As the laser beam is launched, two gas shielded welding arcs also come into play within the molten pool. All three welding nozzles are integrated into a single automatic welding head, allowing for additional welding arcs. This method differs fundamentally from traditional laser hybrid welding technology.
There has been a long-standing competition between laser welding and arc welding technologies. However, their integration brings innovative benefits. Laser gas shielded welding combines higher efficiency with cost savings. At the 2001 International Welding and Cutting Exhibition, Fronius showcased practical and economical laser gas shielding welding equipment for the first time. Since then, 65 such systems have been used in mass production within the automotive industry. These devices are employed to weld aluminum alloys and steel axles, doors, and roof frames, with a maximum plate thickness of 4mm.
The development of new laser gas shielded welding technology has continued to evolve. In 2009, Fronius planned to market lasers and welding equipment designed for two welding electrodes. The laser gas protection welding technology in these systems integrates the advantages of both laser and gas welding. Its versatility and specific benefits stem from the fact that the laser and gas shielded welding tips share one automatic welding head, with the laser beam and two gas shielded arcs working together in the weld pool.
The first tests combining laser and gas shielded welding date back to the 1980s. For over 20 years, this technology remained confined to laboratories without reaching industrial applications. In this hybrid process, both the laser beam and the welding arc act at the weld joint. The laser beam melts deeply into the workpiece with extremely high energy, while the gas shielded welding system delivers consumables and creates a flat, strong weld. This hybrid technology combines the speed and precision of laser welding with the flexibility and strength of gas shielded welding.
Figure 1 shows the laser gas shielded welding pool, highlighting the synergy between the laser and the gas shielded arcs. Users hope that laser gas protection welding equipment becomes more powerful, especially for welding thicker steel plates with better melting methods and faster speeds. According to Fronius technicians, using a laser with two welding electrodes is the best solution. The main challenge lies in integrating the laser tip and two gas shielded tips into a compact automated welding head with minimal distance between the laser beam and the arc.
In addition to technical challenges, the size, movement performance, and accessibility of the welding head must be addressed. Figure 2 displays workpieces welded using laser gas welding, illustrating the practical application of the technology. With this process, steel plates up to 8mm thick can be welded quickly. It is widely used in machine tool manufacturing, pressure vessels, and railway locomotives, where it effectively welds structural steels, ferrite/austenite chrome-nickel steels, and dual-phase steels.
The newly developed laser gas shielded welding head fully integrates the advantages of both technologies. Advanced control software helps coordinate the simultaneous operation of the two processes, managing various parameters during welding. Compared to traditional heads, users expect this system to support five different welding processes: pure laser, laser + brazing, laser + gas shielded, laser + two gas shielded, or one or two gas welds.
In the future, the size of the melting power will no longer be the main factor affecting welding efficiency. Instead, new weld geometry, materials, and tips will determine penetration and weld length per unit time. Compared to earlier generations, the new laser gas welding process offers higher productivity, multiple power supplies, lower procurement costs, and reduced protective gas and accessory expenses. Additionally, labor costs are significantly lower when compared to traditional methods.
This technology also saves on the processing costs of weld bevels. By adjusting the chemical composition of the consumables, toughness and cold cracking resistance can be improved, enhancing the fluidity of molten metal. New laser gas shielded welding allows for larger tolerances on the weld seam, reducing preparation costs. Compared to gas shielded welding, it transfers less heat to the base metal, minimizing deformation and post-welding work.
In fillet welding, the new technology produces smaller weld volumes with the same mechanical strength. Unlike traditional fillet welds, which sit on the surface, the new method welds deeper into the workpiece, resulting in less distortion and better assembly (see Figure 3). This effect is particularly evident in 4mm penetration, where the new weld has a size of only 2mm with an additional 2mm depth inside the workpiece.
Comparing the old and new laser gas shielded welding technologies, the double welding tip configuration offers clear advantages: 25% wider welds, 50-100% faster welding speeds, and 50% more weld volume at the same speed. In typical machinery manufacturing fillet welding, this technology significantly improves the quality of two 2mm thick steel fillet welds.
The highly concentrated laser beam forms a deep molten pool, while the two gas-protected welding tips create perfect surface coverage, one deep and one shallow (Figure 4). This synergy results in stronger and more consistent welds.
The high-speed capabilities of automatic welding equipment further enhance the efficiency of laser gas welding. For example, four gas protection welding units have been used for pressure vessel welding for a long time. Using laser gas welding requires only one device, reducing the welding area by 75% and significantly lowering production costs. Labor costs are also reduced, from four people to just one, making the investment recovery period for laser gas welding equipment less than two years.
Figure 5 showcases a 400mm diameter pressure vessel welded using laser gas shielding, demonstrating the technology’s effectiveness. Figure 6 compares the costs of MSG gas shielded welding and laser gas shielded welding per meter of weld, showing the economic benefits of the latter.
At the 2009 welding and cutting exhibition, the audience witnessed the real-world application of laser gas protection welding under program control. Future developments will focus on single and dual gas protection welding tips, as laser efficiency improves and fiber and Shaben laser technology reduces equipment costs by 20-30%.
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