Lincoln Electric IM649 Wave Designer - Manual (Page 48)

A.6 SECONDARY WAVEFORM PARAMETERS
A.6.1 RAMP-UP RATE
The ramp-up rate is the speed of current climb from the background current level to the peak
current level. Faster ramp-up rates tend to produce a plasma plume that quickly surrounds the
end of the next droplet.
A.6.2 RAMP OVERSHOOT %
The ramp overshoot % can be set from -100% to +100% of the peak amps value. Positive %
overshoot is commonly used to harden the arc. Negative % overshoot (undershoot) is used to
soften the arc for welding. Ramp overshoot can also be used to compensate for variations in the
length of the ground lead which alters the output inductance of the power source.
A.6.3 TAILOUT SPEED
The tailout speed is the rate of amperage decrease from the peak current level to the step-off
current level. Tailout speed decreases exponentially. Tailout speed affects the amount of heat
put into the system just after droplet transfer. Slow tailout speeds (near 0) apply more heat to the
weld system. Rapid tailouts are more likely to short circuit the electrode to the work.
A.6.4 TAILOUT TIME
The tailout time is the duration of tailout. Longer tailout times maintain the system heat longer.
Shorter tailout times can force the output to reach the background current level. Note that the
adaptive loop can not force the wave period (1/pulse frequency) into the tailout region. We
recommend setting the background time long enough to allow the adaptive loop to work.
A.6.5 STEP-OFF AMPERAGE
Step-off amperage is the target current level reached during tailout. The step-off amperage must
be higher than the background current.
A.6.6 BACKGROUND TIME
Background time is the duration of background current. Background time is equal to the
waveform period minus the duration of ramp up, peak time, and tailout. Increasing the
background time decreases the pulse frequency. We recommend setting the background time
long enough to allow the adaptive loop to work.
FIGURE A-8. PULSE WAVEFORM PARAMETERS.
A-16 Appendix A PULSE WAVE SHAPING PRINCIPLES
WAVE DESIGNER
27850034
RAMP-UP RATE
TAILOUT
SPEED
TAILOUT
TIME
STEP-OFF
AMPS
BACKGROUND
TIME
BACKGROUND AMPS
1/FREQUENCY
% OVERSHOOT
PEAK TIME
PEAK
AMPS