Tig Basic Welding Guide; Tig Electrode Selection And Preparation; Electrode Polarity - Weldclass WeldForce WF-255MST Operating Instructions Manual

TIG Welding is a fusion procedure that uses an electric ARC created between an infusible tungsten electrode
and base material to be welded. For TIG welding an inert gas must be used (Argon) which protects the
welding bead. If filling material is used, it is made up of rods suitable to the material to be welded (steel,
stainless steel, copper etc.).
Figure 68
In TIG mode, welding is possible in all positions: flat, angle, on the edge, vertical and overhead.
Furthermore, with respect to other types of welding, the welding joint has greater mechanical resistance,
greater corrosion resistance and limited heating in the welded area which limits distortion. Welding can be
done even without weld material, guaranteeing a smooth, shiny weld with no impurities or slag.

13.1 TIG Electrode Selection and Preparation

13.1.1 Electrode Polarity

Connect the TIG torch to the negative (-) torch terminal and the work lead to the positive (+) 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.
Electrode Type
Rare-Earth
(Weldclass RE4)
Table 19
* Note that the WeldForce WF-255MST machine is only capable of DC TIG welding. It cannot perform
AC TIG welding required to weld Aluminium.
Tungsten Electrode Current Ranges
Electrode Diameter
1.6mm (1/16")
2.4mm (3/32")
3.2mm (1/8")
Table 20
66
Tungsten Electrode Types
Application Features
All metals* High-Performance, suitable for both DC (Steel,
Stainless steel etc) and AC (Aluminium)* TIG
welding. Maintains tip shape, reliable arc
striking, low burn off rate, long service life and
smooth/stable arc.
DC Current (Amps)
60 – 115
100 – 165
135 – 200
© Weldclass 2019 | E.&O.E. | Edition 2.2
Guide For Selecting Filler Wire Diameter
Filler Electrode Diameter DC Current (Amps)
1.6mm (1/16")
2.4mm (3/32")
3.2mm (1/8")
Table 21
.
Colour Code
Purple
20 – 90
65 – 115
100 – 165