Recurring Welding Tasks (Job 1-7); Ac Welding; Ac Balance (Optimise Cleaning Effect And Penetration Characteristics) - EWM T 4.02 - AC/DC Comfort 2.0 Operating Instructions Manual

Functional characteristics
TIG welding
4.1.2.1 Recurring welding tasks (JOB 1–7)
The user has 7 more memory locations at their disposal to save recurring or different welding tasks on a
permanent basis. To do so, simply select the required memory location (JOB 1–7) and the welding task is
set as described previously.
The three rotary knobs for AC frequency, AC balance and the tungsten electrode diameter are
exceptions. These settings are made in the operation sequence (signal lights with same name).
Switching a JOB is only possible if no welding current flows. Up-slope and down-slope times can be set
individually for latched and non-latched operation.
Selection
When one or more of the recurring welding tasks (JOB 1–7) has been selected the JOB signal light
comes on.
4.1.3

AC welding

4.1.3.1

AC balance (optimise cleaning effect and penetration characteristics)

To weld aluminium and aluminium alloys, AC welding is used in combination with a continuous change in
polarity of the tungsten electrode. The process encompasses two phases (half-waves): a positive and a
negative one. The positive phase cracks the aluminium oxide layer on the material surface (so called
cleaning effect).
At the same time, tungsten balling occurs at the tip of the tungsten electrode. The size of this balled end
depends on the length of the positive phase. Please note that an excessively big balled end will cause the
arc to become unstable and diffuse, with low penetration. In the negative phase, the tungsten electrode is
cooled and the required penetration is realised. Make sure to select the correct durations (balance) for
positive phase (cleaning effect, balled end size) and negative phase (penetration depth) by setting the AC
balance. The default (zero setting) balance setting is 65%, referring to the duration of the negative half-
wave.
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Figure 4-2
Figure 4-3
099-00T402-EW501
24.04.2018