Start Welding; Dc Current In Tig Welding - Linde BOC RAPTOR Operating Manual

6.5 Start welding

The machine uses HF to initiate the welding arc.
HF: Keep 2-4 mm space between tungsten
electrode and work piece, press the torch
switch, the machine will start to work after the
pre gas flow time.
When welding is terminated, keep the torch
directed at the weld pool to allow the shielding gas
to protect and cool the solidifying weld metal in
order to prevent defects.

6.6 DC current in TIG welding

For direct current (DC) TIG welding
Select the correct size and type of non consumable
tungsten and shielding gas for the application.
(See Shielding gas selection on page 12.)
For (DC–) (most commonly used polarity) connect
the TIG torch to the negative Dinse plug connector
and the work return lead to the positive dinse
plug connector.
For (DC+) applications connect the TIG torch to the
positive dinse plug connector and the work return
lead to the negative dinse plug connector. In this
mode most of the heat is generated within the
non-consumable tungsten and the heat input into
the plate is reduced resulting in lower penetration
depths. Larger tungstens are normally selected for
this application.
Ensure that the MMA/TIG selector switch is in the
TIG position.
For DC Pulse TIG welding
DC welding of thin material can further be
enhanced by using the pulse mode. When using
the pulse mode for DC applications, the current
will be varied between the welding current and
a pre-selected background current. Additionally,
the pulse frequency can be adjusted. By adjusting
the pulse frequency, the optimum heat input for a
particular application can be obtained.
Downslope control
The downslope of the welding current can
be adjusted by adjusting the Down slope. By
increasing the downslope control time, it allows for
better crater filling characteristics.
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