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History: (Please read history of AC
TIG WELDER first) After success of AC TIG WELDING DC
current was tried and it the DC current cause dirty
welds with oxides entrapped in the welding bead. To
counteract this so called rectifier, manufacturers in
USA used an extremely high voltage with high frequency
spark injector. This system was only partially effective
in cleaning the weld and caused considerable radio frequency
interference. Then Dc current TIG applied for welding
steel instead of aluminum and it gives good results
and commercially supply of DC TIG starts.
Definition: It is an arc welding process where in coalescence
is produced by heating the job with an electric arc
struck between a tungsten electrode and the job. A shielding
gas (argon helium, nitrogen, etc.) is used to avoid
atmospheric contamination of molten weld pool. A filler
metal may be added, if required.
Principle: Tungsten is used as electrode; an arc is
generated between job and electrode by DCSP (Direct
current straight polarity) power source, under coverage
of argon as shielding gas. The arc fuses the job metal
and goes ahead to fuse further metal the molten metal
solidifies by reduction in temperature due to comparative
low temp of air and adjoined metal. |
