The plasma arc welding is known technically as PAW (Plasma Arc Welding) , and uses the same principles as TIG welding, as can be seen as a development of this latter process. However, both the energy density as the temperatures are much higher this process as the plasma state is reached when a gas is heated to a temperature sufficient to achieve its ionization , separating the ions and electrons item . The biggest advantage of the process is PAW that its area of \u200b\u200bimpact is two to three times lower compared to TIG welding, so it becomes an optimal technique for weld metal of small thickness.
plasma the energy needed to get the ionization is provided by the electric arc established between an electrode of tungsten and base metal welding. As arch support is used a gas, usually argon pure or in some cases helium with small amounts of hydrogen , plasma state passing through the orifice of the nozzle which chokes off the bow, turning the base metal a concentrated stream that can reach 28,000 ° C. The plasma gas flow is usually not sufficient to protect the atmosphere to the bow, the molten material and exposed to heat. Thus through the casing of the gun is a second shielding gas that surrounds the joint.
plasma welding - PAW - comes in three forms:
1. Microplasma welding, welding currents from 0.1 Amp. up to 20 Amp.
2. Fusion welding metal to metal, welding current from 20 Amps. up to 100 Amp.
3. Keyhole welding, up from 100 Amp. in which the plasma arc penetrates the entire thickness of the material to be welded.
Mainly used in high-quality bonds such as in aerospace construction, chemical processing plants and oil companies.
