OPERATION
penetration and even fusion. Too short stick out will cause an unstable weld pool, produce spatter and
over heat the contact tip. Too long stick out will cause an unstable arc, lack of penetration, lack of
fusion and increase spatter.
Travel Speed - Travel speed is the rate that the gun is moved along the weld joint and is usually
measured in mm per minute. Travel speeds can vary depending on conditions and the welders skill
and is limited to the welders ability to control the weld pool. Push technique allows faster travel
speeds than Drag technique. Gas flow must also correspond with the travel speed, increasing with
faster travel speed and decreasing with slower speed. Travel speed needs to match the amperage and
will decrease as the material thickness and amperage increase.
Too Fast Travel Speed - A too fast travel speed produces too little heat per mm of travel resulting in
less penetration and reduced weld fusion, the weld bead solidifies very quickly trapping gases inside
the weld metal causing porosity. Undercutting of the base metal can also occur and an unfilled groove
in the base metal is created when the travel speed is too fast to allow molten metal to flow into the
weld crater created by the arc heat.
Too Slow Travel Speed - A too slow travel speed produces a large weld with lack of penetration and
Even arc, good
penetration even
fusion, good finis.
Unstable arc,
spatter, over heat
contact tip.
Unstable arc,
spatter, poor
penetration and
fusion.
lack of joint
penetration
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