Submerged arc welding, also referred to as SAW, is an arc welding process that can be automated with industrial robots. This welding method is most commonly used in the heavy metal industry, railroad industry, and the energy industry for the construction of wind turbines. It is best for welding metal plates with a thickness between two and one hundred millimeters as it is proven to be the most efficient welding method for thicker plate metals or longer welds.
As with other types of arc welding processes, submerged arc welding uses an electric arc to weld together parts. What is different about this welding process is that it uses coarse powder. This powder is referred to as granular flux and typically consists of lime, silica, manganese oxide, calcium fluoride, and other compounds. The flux is melted from the heat generated from the arc and liquid slag forms on the melted metal. The slag layer acts as a protectant from contaminants that could damage the quality of the weld.
The reason why this method is called submerged arc welding is because the molten weld and arc zone are “submerged” under the slag formed from the granular flux. The molten flux helps provide a current path between the electrode and workpieces. In addition to preventing weld contamination, the granular flux also prevents spatter and sparks during welding, resulting in cleaner welds. It suppresses the UV light from the arc and any fumes that develop.
Automating SAW with Robots
Submerged arc welding may be fully automated or semi-automated. Fixed machinery was common for full SAW automation until robotic technology allowed industrial robots to perform submerged arc welding. Robotic SAW involves the integration an industrial robot with welding equipment. The FANUC Arcmate 120ic and the Motoman MA1400 are two examples of welding robots that are ideal for SAW. The industrial robot will be integrated with a welding power supply, wire feeder, welding torch, and a flux delivery system. For complete welding optimization, a robotic weld cell should also be considered. Weld cells maximize efficiency while protecting robot operators or other floor workers from the welding process.Automating submerged arc welding with industrial robots is not as common as other arc welding processes such as robotic MIG and automated TIG welding. It is still relatively new as robotic SAW only started in the past ten years. However, robots from top robotic brands FANUC, ABB, Yaskawa Motoman and KUKA have been used for automating this welding process.
Advantages of Robotic SAW
Automating submerged arc welding applications with industrial robots has many advantages. Robots provide flexible automation with the ability to work with various parts, materials, or processes. When there is a change they can simply be reprogrammed, there is no time lost due to retraining or need to change equipment. Welding robots like the FANUC Arcmate 100ic operate at much faster speeds than manual welders, allowing for more welds in less time. They provide high deposition efficiency, which is key in SAW to produce high-quality welds.Submerged arc welding is relatively easy to convert into an automated process with robots as it requires minimal operator skill. Automating SAW with robots will improve productivity rates, cycle times, and weld quality. For a more economical approach, the FANUC Arcmate 120ib can be used to automate this application. For longer reach applications, the FANUC M710ic/20L or the ABB 4600-20/2.50 can be utilized.