Functional characteristics
Welding programs
099-00T500-EW501
2.9.2022
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5.2.3 AC welding
The welding of aluminium and aluminium alloys is made possible by the periodic change of polarity on the
tungsten electrode.
The negative pole (negative half-wave) of the tungsten electrode determines the penetration characteris-
tics and has a lower electrode load compared to the positive half-wave. The negative half-wave is also
called "cold half-wave".
Whereas the positive polarity, i.e. the positive half-wave, breaks up the oxide layer on the material
surface (the so-called cleaning effect). At the same time, the tungsten electrode tip melts into a ball (the
so-called balled end) due to the high thermal effect of the positive half-wave. The size of the balled end
depends on the length (balance setting
> see 5.2.3.3 chapter
) and the current amplitude (amplitude ba-
lance
> see 5.2.3.4 chapter
) of the positive phase. It should be noted that a balled end that is too large
may lead to an unstable and diffuse arc resulting in a low penetration profile. Therefore, the relationship
between the current amplitude and the balance of the task must be adjusted accordingly.
5.2.3.1 Alternating current waveforms
Selection
4s
Figure 5-6
Display
Setting/selection
Alternating current waveforms
1
------- Rectangular - Highest energy input (ex works)
------- Trapezoidal - An all-rounder, suitable for most applications
------- Sine - Low noise level
1
for AC welding machines only.
