Today it’s getting a little more complicated about plasma welding: Materials can be welded together using a plasma jet as the heat source. Plasma is an arc of super-heated, electrically conductive gas, mostly argon mixed with hydrogen or helium. This protects the weld pool against oxidation and stabilizes the arc. Impulses of high frequency ionize the plasma gas that funnels through the plasma torch. An additional light arc is burning between a wolfram electrode that is polarized negative and an anode built as a nozzle. This ionizes the gas shaft between nozzle and the component, which is polarized positive, and therefore allows an ignition without a touch. Hereby the plasma is constrained to a cylindric gas shaft by a water cooled copper nozzle, which comes along with a higher concentration of energy than in other gas-shielded welding processes. Thus it enables a higher welding speed.
Plasma welding processes exhibit high component positioning tolerances and thus offer advantages when it comes to bridging gaps. The energy density of the plasma jet enables high welding speeds in conjunction with low-pore seams that are largely free from spatter. Furthermore, distortion and tension are relatively low, which is particularly beneficial in the case of large workpieces. This is why this very stable process is often used in the production of containers or pipelines and in the aerospace industry.