Lincoln Electric IM736-D manual Wire Drive Roll, Crater, Burnback, Spot

B-7 OPERATION B-7

In the case of special waveforms designed for pulsed weld- ing aluminum, Pulse on Pulse™, the effect is similar to what occurs with standard pulse. As the Arc Control is increased from +1 to +10 the frequency of the Pulse on Pulse array increases. As the frequency increases the weld bead ripples become less distinct and the arc cone narrows. When the Arc Control is set from -1 to -10 the Pulse on Pulse arrays decrease in frequency, the weld bead ripples become more distinct, and the bead width increases.

•In the GMAW, FCAW, and Power weld modes, crater WFS and voltage are adjustable using the control knobs on the upper case front. This in indicated by the flashing LED’s next to "WFS" and "VOLTS."

•In the GMAW-P weld modes, Crater WFS and trim are adjustable. This is indicated by the flashing LEDs next to "WFS" and "TRIM."

In GMAW-PP mode, arc control adjusts the modulation fre- quency, which means the speed at which the ripples are produced in the weld. (See Pulse-on-pulse description later in this section.) When faster travel speeds are desired, arc control needs to be set higher. When slower travel speeds are desired, arc control needs to be set lower.

•The Arc-control adjustment is selected by toggling the SELECT switch until the LED next to ARC CONTROL is lit. The Arc-control value will be displayed. Arc-control can be adjusted by toggling the SET switch up or down.

•The default value is "OFF."

Crater

The crater is the end of the weld, which normally solidifies creating a concave surface. This can result in stresses that can cause cracks in the center of the crater. The purpose of the Crater control is to fill up the crater, so that its surface becomes flat.

Crater control in this machine is more efficient than in other machines. Normally, in other machines, the crater filling pro- cedure is a step down from the welding WFS to the crater filling WFS. In this machine instead of a step down, the tran- sition is a ramp down, which results in a more controlled fill- ing up of the crater and so, less stresses present in it.

The values to enter are first the desired time to stay at the Crater settings and the desired WFS and voltage/trim to fill the crater.

•The Crater timer is selected by toggling the SELECT switch until the LED next to CRATER is lit and flashing. A crater time may be set using the SET switch.

•The available values for crater control time go from "Off" to 0.1 seconds and from there to 10.0 seconds in incre- ments of 0.1 seconds.

•The Crater function offers the ability to set an endpoint for WFS and Voltage that will be reached over a specified time period. At the end of the weld when the trigger is released, the crater timer will begin and the WFS and Volts settings will ramp down from the Weld Mode WFS and Voltage settings to the Crater WFS and Voltage set- tings over the time selected. This creates a ramp down of the WFS and Volts during the Crater time.

Burnback

Setting the Burnback means setting the adjustable time delay between turning off the wire feeding and turning off the arc. Burnback helps to prevent wire sticking to the pud- dle.

•The Burnback feature will allow current to continue to flow for a specified time period at the end of a weld after wire feeding has stopped.

•The Burnback timer will be selected by toggling the SELECT switch until the LED next to BURNBACK is lit. A burnback time may be set using the SET switch.

•The default value is "OFF" (0 seconds).

•Burnback time is adjustable from 0 to 0.25 seconds in 0.01 second increments.

Spot

The Spot Timer adjusts arc on-time for spot or tack welds.

•With the Spot feature active (Spot time selected), when the trigger is pulled and the arc is established, the weld will continue until the expiration of the spot timer and the next active state will be enabled (crater or burnback). The trigger must be released and pulled again for another Spot cycle.

•The Spot timer is selected by toggling the SELECT switch until the LED next to SPOT is lit. The present SPOT time will be displayed and can be changed by toggling the SET switch up or down.

•The default value is "OFF" (0 seconds).

•Spot can be adjusted from 0 to 10.0 seconds in 0.1 sec- ond increments.

WIRE DRIVE ROLL

The drive rolls installed with the POWER MIG 300 have two grooves, one side for .030" (0.8mm) solid steel electrode, and the other for the .045”(1.2mm) electrode. The actual drive roll size is stenciled on the side opposite of its groove. If feeding problems occur, a check may be required to make sure that the wire size and the drive roll size matches. See "Procedure for Changing Drive Rolls" in this section.

POWER MIG 300