Impax IM-MIG120 Instruction Manual page 41

TIG OPERATION
Scratch the tip of the electrode on soon as an
arc develops, quickly withdraw the electrode to
maintain a gap of approx. 3-4 mm, and proceed
to weld.
To stop welding release the TIG torch trigger.
This method is referred to as 'Scratch Arc'.
Remember to turn off the gas immediately when
you finish welding.
Note: To avoid a visible strike mark on the
surface of the workpiece, it is advisable to strike
the arc in the joint, where the mark will be
concealed by the weld.
Note: Thin sheet and stainless steel may be
welded with or without filler, similar to gas
welding.
Note: The filler is fed in at the edge of the pool.
The rod must not touch the tip of the electrode
or enter the arc. The end of the rod must always
be shielded by the argon atmosphere to prevent
as far as possible the formation of oxides of its
surface. When welding stainless steel and
copper, it is often possible to feed in the filler
continuously at the edge of the pool.
Note: The arc length generally varies between 3
and 6mm depending on the type of joint, type
and thickness of material, and so on.
Note: The torch is advanced in the direction of
welding, without lateral movement, maintaining
the torch angle of 45º to the workpiece.
TIG Welding Fusion Techniques
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 are 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 39.
Fig 39
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