Dc Current In Tig Welding - Linde BOC Smootharc TIG200 DC Operating Manual

36 BOC Smootharc TIG 200 DC Operating Manual
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GTAW with DCEN produces deep penetration because it concentrates the heat in the joint
area. No cleaning action occurs with this. The heat generated by the arc using this polarity
occurs in the work thus a smaller electrode can be used as well as a smaller gas cup and gas
flow. The more concentrated arc allows for faster travel speeds.
7.5

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
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page 12.)
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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.
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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.