PRO-POINT MIG-ARC-TIG 145A Manuel De L'utilisateur page 25

V1.0 145A MULTI-PROCESS MIG-ARC-TIG WELDER 8619470
TIG WELDING FUSION TECHNIQUE
Manual TIG welding is often considered the most difficult of all the
welding processes. Because the welder must maintain a short arc
length, great care and skill is required to prevent contact between
the electrode and the workpiece. Similar to Oxygen Acetylene
torch welding, TIG welding normally requires two hands and in
most instances requires the welder to manually feed a filler wire
into the weld pool with one hand while manipulating the welding
torch in the other.
However, some welds combining thin materials can be
accomplished without filler metal like edge, corner and butt joints.
This is known as fusion welding where the edges of the metal
pieces are melted together using only the heat and arc force
generated by the TIG arc. Once the arc is started the torch
tungsten is held in place until a weld pool is created, a circular
movement of the tungsten will assist is creating a weld pool of the
desired size. Once the weld pool is established tilt the torch at
about a 75° angle and move smoothly and evenly along the joint
while fusing the materials together (Fig. 55).
Fig. 55
TIG WELDING WITH FILLER WIRE TECHNIQUE
It is necessary in many situations with TIG welding to add a filler wire into the weld pool to build
up weld reinforcement and create a strong weld. Once the arc is started, the torch tungsten is
held in place until a weld pool is created, a circular movement of the tungsten will assist is
creating a weld pool of the desired size. Once the weld pool is established, tilt the torch at
about a 75° angle and move smoothly and evenly along the joint (Fig. 56). The filler metal is
introduced to the leading edge of the weld pool. The filler wire is usually held at about a 15°
angle and fed into the leading edge of the molten pool, the arc will melt the filler wire into the
weld pool as the torch is moved forward. Also a dabbing technique can be used to control the
amount of filler wire added, the wire is fed into the molten pool and retracted in a repeating
sequence as the torch is moved slowly and evenly forward (Fig 57). It is important during the
welding to keep the molten end of the filler wire inside the gas shield as this protects the end of
the wire from oxidizing and contaminating the weld pool.
Fig. 57
Fig. 56
TUNGSTEN ELECTRODES
Tungsten is a rare metallic element used for manufacturing TIG welding electrodes. The TIG
process relies on tungsten's hardness and high-temperature resistance to carry the welding current
to the arc. Tungsten has the highest melting point of any metal 6,170 °F (3,410 °C).
Tungsten electrodes are non-consumable and come in a variety of sizes, they are made from pure
tungsten or an alloy of tungsten and other rare earth elements. Choosing the correct tungsten
depends on the material being welded, the amount of amps required and whether you are using
AC or DC welding current.
Tungsten electrodes are colour-coded at the end for easy identification.
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