29-12-2012, 12:30 PM
Plasma Arc Welding
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Welding
Welding is a process of joining two materials with the help of heat or pressure or by some other means.
The cost of welding is very less as compared to other processes and forms a strong joint.
So, Basically the main purpose of welding is to join two pieces.
It is Largely Used in the following fields of engineering:-
Manufacturing of machine tools,autoparts, cycle parts etc.
Fabrication of farm machinery and equipment, and buildings, Bridges and Ships.
Construction of Boilers, Furnaces, Railways, Aeroplanes, Rockets and Missiles.
Manufacturing of TV Sets, Refrigerators, Kitchen Cabinets etc.
What is Plasma Arc Welding?
Plasma arc welding (PAW) is a advanced version of the tungsten inert gas (TIG) welding process.
In which, a mixture of gases such as argon, hydrogen and helium is passed through an electric arc due to heat it is ionised. This is called as to be plasma and it is passed through welding torch.
The piece of metal to be joined is heated through this and tongeston electrode is used as filler material with water as a cooling agent.
This can be used for cutting.
It is a development of the TIG method, which is designed to increase productivity.
History
The plasma welding process was introduced to the welding industry in 1964 as a method of bringing better control to the arc welding process in lower current ranges. Today, plasma retains the original advantages it brought to industry by providing an advanced level of control and accuracy to produce high quality welds or precision applications and to provide long electrode life for high production.
How Plasma Welding Works
A plasma is a gas which is heated to an extremely high temperature and ionized so that it becomes electrically conductive. Similar to GTAW (Tig), the plasma arc welding process uses this plasma to transfer an electric arc to a work piece. The metal to be welded is melted by the intense heat of the arc and fuses together.
PAW is used in three modes:
Microplasma welding, with welding current from 0.1A to 20A.
Medium-plasma welding, with welding current from 20A to 100A.
Keyhole welding, above 100A, where the plasma arc penetrates the wall thickness.
It is widely used for high-quality joints in the aircraft/space, process, chemical industries.