20-09-2016, 02:35 PM
1455376398-PlasmaArcWeldingProcess.pptx (Size: 6.78 MB / Downloads: 2)
Summary
Plasma Arc Welding (PAW) was invented and patented in 1953, by Robert M. Gage, at the Linde/Union Carbide laboratory in Buffalo NY. About 10 years of development and multiple subsequent patents occurred before the devices were brought to market in 1964.
The plasma welding process was introduced to the welding industry 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 in miniature or precision applications and to provide long electrode life for high production requirements.
The plasma process is equally suited to manual and automatic applications. It has been used in a variety of operations ranging from high volume welding of strip metal, to precision welding of surgical instruments, to automatic repair of jet engine blades, to the manual welding of kitchen equipment for the food and dairy industry.
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.
In the plasma welding torch a Tungsten electrode is located within a copper
nozzle having a small opening at the tip. A pilot arc is initiated between the
torch electrode and nozzle tip. This arc is then transferred to the metal to be
welded.
By forcing the plasma gas and arc through a constricted orifice, the torch delivers a high concentration of heat to a small area. With high performance welding equipment, the plasma process produces exceptionally high quality welds.
Plasma gases are normally argon. The torch also uses a secondary gas, argon, argon/hydrogen or helium which assists in shielding the molten weld puddle thus minimizing oxidation of the weld.