TIG welding is most commonly used for welding thin metal stainless steel and nonferrous metals such as aluminum, magnesium and copper alloys. The process grants the operator greater control over the welding process of competition, such as welding metal arc welding and gas metal arc, allowing for stronger, high quality welds. However, the TIG is comparatively more complex and difficult to master, and, moreover, is significantly slower than most welding techniques. A related process, the plasma arc welding uses a welding torch to create a slightly different arc welding more focused and result often is automatic.
Manual gas tungsten arc welding is often considered the most difficult of all the welding processes used in industry. Because the welder must maintain a short arc length, great care and skill necessary to prevent contact between the electrode and the workpiece. Similar to the torch GTAW normally requires two hands, since most applications require the welder manually feed a filler metal in the welding area with one hand while manipulating the torch in the other. However, some welds on the combination of fine materials (known as welding or melting) can be achieved without filler metal, especially edge, corner and butt joints.
To ignite the arc welding, a high frequency generator (similar to a Tesla coil) provides an electric spark, the spark is a conductive path for welding current through the shielding gas and allows the arc that began while the electrode and the workpiece is separated, usually about 1.5 to 3 mm (0.06 to 0.12 in) away. This burst of high voltage, high frequency can be detrimental to some electrical and electronic systems due to the stress induced in the wiring of the vehicle can also cause small sparks driving the vehicle wiring or semiconductor packaging. Vehicle power of 12 V can be carried out through these roads ionized, driven by the battery of 12 V vehicle power high. These currents can be destructive enough to disable the vehicle, so that the warning to disconnect power from the vehicle battery of two 12 and the ground before using welding equipment in vehicles.
An alternative method for starting the arc is the "start from scratch." Scratching the electrode against the work's power also serves to create an arc in the same way as SMAW ("stick") arc welding. However, from the ground can contaminate the weld and the electrode. Some GTAW equipment is capable of a mode called "start play" or "bow lift" here the equipment reduces the voltage at the electrode only a few volts with a current limit of one or two amplifiers (well below the limit that causes the metal to the transfer and contamination of the weld or electrodes). When the computer detects that the electrode GTAW has left the surface and a spark is present, immediately (in microseconds) of energy increases, the conversion of the spark of a full arc.
Once the arc is struck, the welder moves the torch in a small circle to create a welding set, the size of which depends on the size of the electrode and the amount of power. Maintaining a constant separation between the electrode and the workpiece, the operator moves the torch back and slightly tilted back about 10-15 degrees from vertical. Filler metal is added manually to the front of the weld as necessary.
Welders often develop a technique to quickly switch between moving the torch forward (to advance the weld) and the addition of filler metal. The filler metal is removed from the weld every time the electrode advances, but never removed from the shielding gas to prevent oxidation of the surface and contaminating the weld. Filled bars composed of metals with low melting temperature, such as aluminum, require the operator to maintain a certain distance from the arc during their stay in the shield gas. Being too close to the arc, the filler rod may melt before it touches the weld puddle. As the weld ends, the arc current is often reduced gradually to allow the crater welding to secure and prevent cracking of the crater at the end of the weld.
While the aerospace industry is one of the main users of welding gas tungsten arc, the process used in a number of other areas. Many industries use GTAW welding thin pieces, especially nonferrous metals. Is widely used in the manufacture of the spacecraft, and is often used to weld small diameter, thin wall tubing, as used in the bicycle industry. In addition, GTAW is often used to weld root or first-pass piping of various sizes. Maintenance and repair, the process is commonly used for the repair tool and die, especially aluminum and magnesium components. Because the weld metal is not transferred directly through the arc as most arc welding processes open a wide range of welding filler metals available for the welding engineer. In fact, no other welding process allows welding of alloys of many in so many product configurations. Filler metal alloys such as aluminum and elemental chromium may be lost by the arc of volatilization. This loss does not occur with the GTAW process. Because the resulting welds have the chemical integrity of the base metal to original or base metals match more closely, the TIG welds are highly resistant to corrosion and cracking for long periods of time, GTAW welding procedure is of choice for critical welding operations, such as sealed containers of spent nuclear fuel before burial.
Source: http://en.wikipedia.org/wiki/Gas_tungsten_arc_welding
