Lincoln Electric IM924 POWER WAVE 455M_STT - Manual (Page 28)

B-8 OPERATION B-8
PULSE WELDING
Pulse welding procedures are set by controlling an
overall "arc length" variable. When pulse welding, the
arc voltage is highly dependent upon the waveform.
The peak current, back ground current, rise time, fall
time and pulse frequency all affect the voltage. The
exact voltage for a given wire feed speed can only be
predicted when all the pulsing waveform parameters
are known. Using a preset voltage becomes impracti-
cal, and instead the arc length is set by adjusting "trim".
Trim adjusts the arc length and ranges from 0.50 to
1.50, with a nominal value of 1.00. Trim values greater
than 1.00 increase the arc length, while values less
than 1.00 decrease the arc length.
Most pulse welding programs are synergic. As the wire
feed speed is adjusted, the Power Wave will automati-
cally recalculate the waveform parameters to maintain
similar arc properties.
POWER WAVE 455M/STT (CE)
Wave Control 0.0
Wave Control +10.0
Wave Control -10.0
FIGURE A.6
Current
Time
CURRENT WAVE FORM (PULSE)
The Power Wave utilizes "adaptive control" to com-
pensate for changes in electrical stick-out while weld-
ing. (Electrical stick-out is the distance from the contact
tip to the work piece.) The Power Wave waveforms are
optimized for a 0.75" (19mm) stick-out. The adaptive
behavior supports a range of stickouts from 0.50"
(13mm) to 1.25" (32mm). At very low or high wire feed
speeds, the adaptive range may be less due to reach-
ing physical limitations of the welding process.
Arc Control, often referred to as wave control, in pulse
programs usually adjusts the focus or shape of the arc.
Wave control values greater than 0.0 increase the
pulse frequency while decreasing the background cur-
rent, resulting in a tight, stiff arc best for high speed
sheet metal welding. Wave control values less than 0.0
decrease the pulse frequency while increasing the
background current, for a soft arc good for out-of-posi-
tion welding.
(See Figure A.6)