Table of Contents
Advertisement
34
BOC Smootharc Advance III MIG 225C & 255C Operating manual
11.0 Gas tungsten arc welding (GTAW/TIG)
Schematic of the TIG welding process
Shielding gas
Arc
TIG filler rod
Weld pool
11.1 Introduction
The Tungsten Inert Gas, or TIG process, uses the heat generated by an
electric arc struck between a non-consumable tungsten electrode and
the workpiece to fuse metal in the joint area and produce a molten
weld pool. The arc area is shrouded in an inert or reducing gas shield to
protect the weld pool and the non-consumable electrode. The process
may be operated autogenously, that is, without filler, or filler may be
added by feeding a consumable wire or rod into the established weld
pool.
11.2 Process
Direct or alternating current power sources with constant current output
characteristics are normally employed to supply the welding current.
For DC operation the tungsten may be connected to either output
terminal, but is most often connected to the negative pole. The output
characteristics of the power source can have an effect on the quality of
the welds produced.
Shielding gas is directed into the arc area by the welding torch and a
gas lens within the torch distributes the shielding gas evenly over the
weld area. In the torch the welding current is transferred to the tungsten
electrode from the copper conductor. The arc is then initiated by one of
several methods between the tungsten and the workpiece.
Collet
Tungsten electrode
Workpiece
Advertisement
Table of Contents
