Tweco 300 MST Arcmaster - Manual (Page 36)

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5.0 BASIC WELDING GUIDE
5.01 Electrode Polarity
Connect the TIG torch to the - / TORCH terminal and the work lead to the + / WORK terminal for direct
current straight polarity. Direct current straight polarity is the most widely used polarity for DC TIG welding.
It allows limited wear of the electrode since 70% of the heat is concentrated at the work piece.
5.02 Tungsten Electrode Current Ranges
Electrode Diameter AC Current (Amps) DC Current (Amps)
0.040” (1.0mm) 30 – 70 30 – 60
1/16” (1.6mm) 60 – 95 60 – 115
3/32” (2.4mm) 125 – 150 100 – 165
1/8” (3.2mm) 130 – 225 135 – 200
5/32” (4.0mm) 190 – 280 190 – 280
3/16” (4.8mm) 250 – 340 250 – 340
Table 7 – Current Ranges for Various Tungsten Electrode Sizes
5.03 Tungsten Electrode Types
Electrode Type
(Ground Finish)
Welding Application Features Color
Code
Thoriated 2%
DC welding of mild steel,
stainless steel and copper. Excellent arc starting, Long life,
High current carrying capacity.
Red
Zirconated 1%
High quality AC welding of
aluminium, magnesium and
their alloys. Self cleaning, Long life,
Maintains balled end, High
current carrying capacity.
White
Ceriated 2%
AC & DC welding of mild steel,
stainless steel, copper,
aluminium, magnesium and
their alloys. Longer life, More stable arc,
Easier starting, Wider current
range, Narrower more
concentrated arc.
Grey
Table 8 – Tungsten Electrode Types