Cold lap
Lack of fusion
Lack of joint penetration
Porosity
Large wide bead
Too Slow Travel Speed
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
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.
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.
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.
VIPER MIG 185 Manual |
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MIG WELDING GUIDE
