Firepower MST 140i, Operating Manual

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Firepower MST 140i
BASIC WELDING GUIDE 4-20 Manual 0-5338
4.06 TIG (GTAW) Basic Welding Technique
Gas Tungsten Arc Welding (GTAW) or TIG (Tungsten Inert Gas) as it is commonly referred to, is a welding process in which
fusion is produced by an electric arc that is established between a single tungsten (non-consumable) electrode and the work
piece. Shielding is obtained from a welding grade shielding gas or welding grade shielding gas mixture which is generally
Argon based. A filler metal may also be added manually in some circumstances depending on the welding application.
Welds Made With or Without
Addition of Filler Metal
Work Piece
Can Be Any Commercial
Metal
Gas Cup
Either Ceramic,
High Impact or
Water Cooled
Metal
Inert Gas
Shields Electrode
and Weld Puddle
Tungsten Electrode
Non-Consumable
Art # A-10369_AB
Figure 4-38: TIG Welding Application Shot
Tungsten Electrode Current Ranges
Electrode Diameter DC Current (Amps)
0.040” (1.0mm) 30-60
1/16” (1.6mm) 60-115
3/32” (2.4mm) 100-165
1/8” (3.2mm) 135-200
5/32” (4.0mm) 190-280
3/16” (4.8mm) 250-340
Table 4-6: Current Ranges for Various Tungsten Electrode Sizes
Guide for Selecting Filler Wire Diameter
Filler Wire Diameter DC Current Range (Amps)
1/16” (1.6mm) 20-90
3/32” (2.4mm) 65-115
1/8” (3.2mm) 100-165
3/16” (4.8mm) 200-350
Table 4-7: Filler Wire Selection Guide