On September 26, 2022, the Antarctic bear learned that the engineers of the Fraunhofer ILT in Germany announced the development of a new optical system, which combines metal shielding gas (MSG) welding with laser surfacing using annular light beams by using glass substrates and arc welding torches, thus creating a new manufacturing process - "CollarHybrid".
This process can improve the welding speed and deposition speed of metal 3D printing. It combines wire arc additive manufacturing (WAAM) and wire laser material deposition (WLMD). These two processes have their own advantages and disadvantages, depending on the system.
Laser technology is very expensive and has low deposition rate. Arc wire additive manufacturing is a mature and stable process. However, the arc is directional. When connecting three-dimensional welds, it cannot focus as accurately as the laser beam, nor can it produce fine and accurate tracks as the laser beam, which has certain limitations. In contrast, the laser has a lower heat input and can accurately align the layer structure. Therefore, laser technology is often used in the aerospace field. Compared with wire laser material deposition (WLMD), the deposition rate of WAAM is higher. In welding, the combination of laser beam welding and gas shielded metal arc welding is named LB-GMA hybrid welding. However, this lateral process is direction dependent and is not very suitable for three-dimensional weld connection.
When the two processes are coaxially combined into one system, the welding speed is increased by about 100%, and the deposition rate can be increased by up to 150%, which can even be used for 3D printing of large parts. Max Fabian Steiner, research assistant of Fraunhofer Laser Technology Research Institute in Germany, pointed out that compared with WAAM process, the amount of post-treatment required by this combination process was significantly reduced due to the reduction of surface ripple.
Combination process ensures synergy
Steiner and his colleague Jana Kelbassa in the research institute have developed and built a special water-cooled optical system, which can use glass substrate and water-cooled arc torch to carry out welding and additive manufacturing under high-power laser beam. In the new optical system, two kinds of energy are superimposed, and the combination of two separate processes can be said to complement each other.
In the mixing process, the arc between the end of the wire and the substrate is surrounded by ring laser radiation, just like a ring, and the arc line cannot break through the ring. This new process gets its name from "forced guidance". The abbreviation "COLLAR" refers to the coaxial laser arc shared by the two processes.
Germany's Fraunhofer Laser Technology Research Institute is using new system technology to further develop metal 3D printing and annular laser beam and arc technology, and Germany's Institute of Welding and Connection (ISF) of Aachen University of Technology is using its hybrid welding and annular focusing and coaxial wire feeding process. These two application cases are part of the distributed switch research project "KoaxHybrid".
The initial test results showed that the welding efficiency of the new hybrid process was improved by about 100% compared with that of arc welding. The other option is the COLLAR process, which can be welded in any direction. In addition, it is sufficient to meet the requirements of thick plate welding.
Arcs and lasers work together
When it is necessary to manufacture very fine or rough structures, the parameter proportion of this process can also be adjusted according to the actual situation. Using pure laser technology or multi laser technology (fully closed loop arc or low power), the previously challenging regional structures and fine structures can be deposited; Using the multi arc welding process, it is possible to create a thicker structure (such as wide ribs or areas with high deposition rate), and to deposit at a significantly faster, more cost-effective and lower energy input.
Similar construction strategies are also applicable to materials such as aluminum or copper. In the past, such operations usually require much more expensive blue or green laser beam sources. For example, if an electric arc is used to crush the aluminum oxide layer, its melting temperature is 2200 ℃. However, the lower aluminum layer can be welded or processed with lower comprehensive power because it has only 660 ℃ melting temperature.
Source: Polar Bear 3D Printing Network
