Lincoln Electric IM649 manual Secondary Waveform Parameters

A-16 PULSE WAVE SHAPING PRINCIPLES Appendix A

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.

PEAK TIME

% OVERSHOOT

PEAK

AMPS

TAILOUT

TIME

TAILOUT SPEED

STEP-OFF

AMPS

BACKGROUND AMPS

BACKGROUND

TIME

1/FREQUENCY

27850034

WAVE DESIGNER