Arc Welding, usually referred to as TIG welding (Tungsten Inert Gas
welding), is a welding procedure using a non-consumable electrode
, shielding gas (usually inert
) and filler
wire fed by hand. The electrode is mounted coaxial
ly in the center of the gas nozzle. While the arc is maintained between the workpiece
, the inert gas shield
s the molten weld pool from atmospheric contamination
. The filler metal comes in rods of various diameters and metal compositions.
GTAW's benefits include:
- Superior welds
- Very fine control over welding parameters - travel speed, heat of weld pool, depth of weld, amount of filler metal used, etc...
- No splatter
- Small distortion of workpiece
- Clean, precise welds
GTAW is one of the cleanest, most precise welding procedures available. The operator has complete control over all welding variables and can change most during the welding process with no need to stop the weld. GTAW does have a few disadvantages,
- Slower than most other weld procedures
- Operator must be very close to weld in progress
- Equipment is more expensive and complex than for other welding procedures
- Requires more operator skill
This welding procedure can be used with DC, both straight and reverse polarity as well as AC. Nearly every weldable metal in existance can be joined with Gas Tungsten Arc Welding.
The shielding gas used depends on the metal to be welded. Argon is used for most steels and aluminum, although Helium, Carbon Dioxide, Oxygen and mixes of these gases can also be used for special applications. These other gases aren't inert, so the process is then called TAG welding (Tungsten Active Gas). The electrodes are Tungsten sometimes with trace bits of other metals alloyed in, depending on the application. 2% Thoriated electrodes are a common, as are pure Tungsten.
A remote control of some sort is used to control the arc, thereby controlling the amount of heat on the material. A foot pedal or finger control on the torch are most commonly used. The arc can be varied from extremely small (enough to see the workpiece with the weld hood on) to full blast (melting material as fast as you can feed it into the weld pool).
To run a bead of weld with GTAW, you first must have the weld machine set up and proper protective gear. Hold the TIG torch in one hand (ususally your dominant hand) and the filler wire in the other. Rest the cup of the torch on the workpiece, get the wire in position, flip down the weld hood and start the arc. When a small pool of molten metal has been developed, add filler material until a satisfactory bead has been started. Walk the torch along the workpiece, maintaining a weld pool and adding filler material as you go along. No cleaning is necessary when the bead is completed.
Disclaimer:don't do this unless you know what you're doing or have proper supervision. wear proper safety gear. if you get hurt, it's your own damn fault. remember, you're melting metal with electricity here. IT MIGHT GET HOT AND SPARKY. YOU MIGHT GET BURNED OR SHOCKED.
kiladogg says my metal shop teacher told us that tig welds are the SEXY welds...
Yes, this is true. Good TIG welds are clean, neat, precise and have a soft scalloped appearance. SEXY.