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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, increas-
ing 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 Slow Travel Speed - A too slow travel speed produces a large weld with lack of penetration
and fusion. The energy from the arc dwells on top of the weld pool rather than penetrating the
base metal. This produces a wider weld bead with more deposited weld metal per mm than is
required resulting in a weld deposit of poor quality.
cold lap
lack of fusion
lack of joint penetration
porosity
large wide bead
Too Slow Travel Speed
Correct Travel Speed - The correct travel speed keeps the arc at the leading edge of the weld
pool allowing the base metal to melt sufficiently to create good penetration, fusion and wetting out
of the weld pool producing a weld deposit of good quality.
good toe fusion
good penetration
good side wall fusion
even shaped bead
Correct Travel Speed
spatter
undercut
lack of joint penetration
lack of fusion
porosity
high narrow bead
Too Fast Travel Speed
Too Fast Travel Speed - A too fast travel speed produces too little heat per inch 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 un-
filled 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.
