Migatronic NAVIGATOR 2500 Manuel D'instruction page 18

Four-stroke
This symbol means contact-free striking. The
arc is established in the following way:
1) The torch is placed so that the Tungsten electrode
is quite close to the welding spot (1 or 2 mm).
2) The torch trigger is activated, and the high voltage
generator of the machine will produce a voltage
impulse that ignites the arc.
The torch trigger is deactivated. The welding
process will stop when the torch trigger is re-
activated. The arc will extinguish after the period of
slope-down time. The torch is held at the welding
spot until after the period of gas post-flow time in
order to protect the welding spot against oxidation.
Two-stroke
This symbol means LIFTIG ignition. The arc
is established in the following way:
1) The torch is placed so that the Tungsten electrode
has contact with the welding spot.
2) The torch trigger must be kept pressed down.
3) The arc is established by lifting the torch, and the
welding process has started. In order to stop the
welding process, the torch trigger is deactivated.
The arc will extinguish after the period of slope-
down time. The torch is held at the welding spot
until after the period of gas post-flow time in order
to protect the welding spot against oxidation.
Four-stroke
This symbol means LIFTIG ignition. The arc
is established in the following way:
1) The torch is placed so that the Tungsten electrode
has contact with the welding spot.
2) The arc will be established when the torch trigger is
activated and the torch is lifted. In order to stop the
welding process, the torch trigger is reactivated.
The arc will extinguish after the period of slope-
down time. The torch is held at the welding spot
until after the period of gas post-flow time in order
to protect the welding spot against oxidation.
Please note! Both HF as well as LIFTIG ignition
cannot be effected until post-flow is finished.
Pilot arc
In this section it is possible to
choose whether the pilot arc should be activated or
not. Connection/disconnection of this function cannot
be changed during the welding process.
The pilot arc cannot be activated
The pilot arc can be activated
Used only in the TIG welding process, a pilot arc is a
weak arc which illuminates the workpiece, and thereby
makes it easier to find the starting point of the actual
welding process.
The pilot arc can be ignited by briefly activating the
torch trigger (less than 0.3 seconds). If activation is
longer (more than 0.3 seconds), the machine switches
automatically to ordinary welding.
Switch from pilot arc to ordinary welding by keeping
the torch trigger activated when two-times TIG-welding
or by long activation (>0.3 seconds) when four-times
TIG or spot welding. The welding process then
continues in normal fashion.
However, after slope-down the machine does not
switch directly to post-flow but to pilot arc again. It is
now possible to continue with a new welding process
by a lengthy activation of the torch trigger (> 0.3
seconds), or to go to standby automatically by a brief
activation (< 0.3 seconds).
Pre-flow
Pre-flow is the period of time for which gas
flows after the torch switch is pressed and before the
HF arc is established, or until the torch is lifted away
from the workpiece in the LIFTIG process. Variable 0-
10 secs.
Start Amp
Immediately
established, the machine regulates the welding current
to the value stated in the Start Amp parameter. Start
Amp is set as a percentage of the required welding
current and is variable between 0-100% of the welding
current with a minimum value of 5 A.
Slope-up
Once the arc has been established, the weld-
ing process enters a slope-up stage during which the
welding current is increased in linear fashion from the
value stated in the Start Amp parameter to the
required welding current. The duration of this slope-up
time is variable 0-10 secs.
Slope-down
When welding has stopped by activating the
trigger, the machine enters a slope-down stage.
During this stage current is reduced from welding cur-
rent to Stop Amp over a period of time called the
slope-down time and variable 0-10 secs.
Stop Amp
The slope-down stage is completed when the
current level has fallen to the value stated in the Stop
Amp parameter. Stop Amp is stated as a percentage
of the required welding current and is variable be-
tween 0-100% of the welding current with a minimum
value of 5 A.
18
The welding process
for TIG welding
The parameters can be
selected and adjusted
during the welding pro-
cess.
after the arc has been