Lincoln Electric IM736-D Pulse-On-Pulse Gmaw-Pp, Benefits of Pulse on Pulse from Lincoln Electric

B-11 OPERATION B-11

PULSE-ON-PULSE™ (GMAW-PP)

Pulse on Pulse™ is a Lincoln process specifically designed for use in welding relatively thin (less than 1/4" thick) aluminum (See Table B.3). It gives weld beads with very consistent uniform ripple.

In Pulse on Pulse modes, two distinct pulse types are used, instead of the single pulse type normally used in GMAW-P. A number of high energy pulses are used to obtain spray transfer and transfer metal across the arc. Such pulses are shown in Figure B.6. After a number "N" of such pulses, depending on the wire feed speed used, an identical number "N" of low ener- gy pulses are performed. These low energy pulses, shown in Figure B.6, do not transfer any filler metal across the arc and help to cool the arc and keep the heat input low.

FIGURE B.6

"N" PULSES	"N" PULSES
HIGH HEAT	LOW HEAT
PULSES	PULSES
PEAK
AMPS
BACKGROUND
AMPS
	TIME

The Peak Current, Background Current, and Frequency are identical for the high energy and low energy pulses. In addition to cooling the weld down, the major effect of the low energy pulses is that they form a weld ripple. Since they occur at very regular time intervals, the weld bead obtained is very uniform with a very consistent ripple pattern. In fact, the bead has its best appearance if no oscillation of the welding gun ("whipping") is used.(See Figure B.7)

FIGURE B.7

When Arc Control is used in the Pulse on Pulse modes, it does the same things it does in the other pulsed modes: decreasing the Arc Control decreases the droplet transfer and weld deposition rate. Increasing the Arc Control increases the droplet trans- fer and weld deposition rate. Since Arc Control varies weld droplet transfer rate, the Arc Control can be used to vary the ripple spacing in the weld bead.

BENEFITS OF PULSE ON PULSE FROM LINCOLN ELECTRIC

•Excellent appearance of the weld bead

•Improved cleaning action

•Reduced porosity

Table B.3 shows WFS and Trim settings for common aluminum types and wire sizes when welding with Pulse-on-Pulse. The welds made to obtain the values in the table were fillet welds in the flat position. The values in the table can be helpful as a starting point to establish a welding procedure. From there, adjust- ments need to be made to set the proper procedure for each specific application (out-of-position, other types of joints, etc.).

The comments on Table B.3 show values of WFS below which it is not recommended to weld. The rea- son is, that below these values the weld transfer will change from a spray arc to a short-arc, which is not advisable when welding aluminum.

WELDING PROCEDURES FOR PULSE-ON-PULSE (TABLE B.3)

MATERIAL			Aluminum 4043	Aluminum 4043	Aluminum 5356	Aluminum 5356
	GAS		100% Ar.	100% Ar.	100% Ar.	100% Ar.
	WIRE		E4043	E4043	E5356	E5356
WIRE SIZE			0.035	3/64	0.035	3/64
WELD MODE			98	99	101	102
MATERIAL THICKNESS	TRIM/WFS	14 ga.	250 / 1.0	200 / 1.0	230 / 1.0	225 / 1.0
		10 ga.	400 /1.0	280 / 1.0	425 / 1.0	400 / 1.0
		3/16	550 / 1.0	340 / 1.0	670 / 1.0	500 / 1.0
		1/4	600 / 1.0	400 / 1.0	700 / 1.0	550 / 0.9
COMMENTS			Not Recommended	Not Recommended	Not Recommended	Not Recommended
			below 200 WFS	below 100 WFS	below 200 WFS	below 200 WFS

POWER MIG 300