Migatronic NAVIGATOR 2500 Manuel D'instruction page 20

Spot time
The spot time in TIG is the time from the end of slope
up to beginning of slope down. Therefore, the spot
time is welding with the adjusted current. The time with
the arc and torch trigger activated is the spot time plus
slope up time and slope down time.
Amp
slope-up
Set welding
current
If spot time is changed during welding, this change will
not be carried into effect until next welding process. It
is possible to interrupt the spot welding time by re-
leasing the torch trigger.
AC-welding
This panel is divided into two
sections, with the function current
type at the top, and the setting of
conditions for special AC-functions at
the bottom.
Current type
It is possible to select either AC
(alternating current) or DC (direct
current). In the TIG-welding process, AC is used for
the welding of aluminium and its alloys, while DC is
used for the welding of other materials.
When TIG welding aluminium or its alloys the positive
part of the AC-wave removes the oxide film covering
the surface of the workpiece, and the negative part of
the wave melts the material.
AC-frequency
The AC frequency can be adjusted from 1 to 300 Hz
for TIG welding and from 1 to 100 Hz for MMA-
welding. A low frequency during TIG welding in-
creases the tendency for the formation of a large ball
at the end of the tungsten electrode. This tendency will
be reduced by increasing the frequency.
Note 1: The AC frequency and welding current cannot be
adjusted to maximum simultaneously during TIG
welding - see the following illustration. When the
limit is reached by adjusting the AC-frequency, the
A-lamp will illuminate in "units for parameter" and
the machine will reduce the AC frequency auto-
matically.
Note 2: If the frequency limit is exceeded by adjustment of
the welding current the AC frequency will be
reduced automatically
frequency flashes on and off for 5 sec.).
spot
welding time
slope-down
time
trig down ( ) / up ( )
(the indicator for
Note 3: If the pulse function is used during AC-welding the
AC frequency can be reduced in proportion to the
pulse times. If the AC frequency is to low the
indicators for pulse times will flash on and off for 5
seconds.
Note 4: Pulse adjustment error: If the pulse function is used
during AC-welding an automatic adjustment of the
pulse setting may occur. The indicators for pulse
times will then flash on and off for 5 seconds. The
pulse times change automatically so the pulse time
and base time will be 0.03 seconds.
Electrode preheating (TIG)
On ignition of the AC TIG pilot arc the tungsten
electrode is preheated by a direct current with positive
polarity. Preheating of an electrode is necessary
before starting the AC welding process. The length of
the preheat period depends on both the diameter of
the electrode and the angle of the point of the
electrode, as well as the size of the ball at the end of
the electrode.
Adjustment is possible from -9 to +9, with -9 being the
minimum and +9 being the maximum preheat periods.
If the period is too short the pilot arc will extinguish
shortly after ignition. The size of the ball at the end of
the electrode will increase if the pre-heat period is too
long.
AC-t-balance, based on time (TIG)
Adjustment of the refinement function during the
AC TIG welding of aluminium and its alloys. The
function is a balance based on time between the
positive and negative halfperiod.
Adjustment is possible between 1 and 100 per cent as
the statement in per cent is based on the negative part
of the period time. Adjustment continues until a suit-
able refinement zone is established around the molten
pool. When MMA welding the balance can be locked
at 50 per cent which means that further regulation is
impossible.
AC-I-balance, based on current intensity
(TIG)
The purpose of the function is also adjustment of the
AC
refinement zone during AC TIG welding.
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