Lincoln Electric Making Fillet Welds manual 4/10, Square Wave Offset Effect, Welding Guide

W A V E F O R M C O N T R O L T E C H N O L O G Y T M

APPLICATION

Making Fillet Welds with Power Wave AC/DC 1000™ System	4/10
Welding Guide

Square Wave Offset Effect

Offset is expressed as a percentage between -25% and +25% of the rms2 value that is kept positive or negative. In other words, -25% means the normal positive component of each cycle is held to 25% of the normal rms value and the negative component becomes 75%. In some respects, when offset is adjusted to maximum values, the arc action almost becomes analogous to that of a pulsed arc. Negative values contribute to increasing deposition to levels closely approaching the values obtainable with DC negative welding. See Figure 5.

Figure 6 shows two welds: the same 3/8” (10mm) flat position fillet as Figure 3, but this time made using a setting of 25% balance, (-)10% offset. Note that this results in an additional gain of 12% in travel speed!

This is a net gain of 29% over DC+.

The increased deposits possible using a combination of wave balance and wave offset may raise the question about root penetration. While at present the major welding codes do not allow sizing a fillet weld based on root penetration, some producers of proprietary products do. Figure 7 shows the depth of penetration as compared to DC+ for a number of settings. This shows a variation of only .05” (1.3mm) in penetration, a variation of nine to ten percent. All of the welds were made when the plate was at room temperature and at 54.25Kj heat input.

		Square Wave - Normal Curve
		Square Wave - Negative Offset
Total Amps	50% Positive
	0	Total Amps
	50% Negative

1 CYCLE

1/60 SECOND

Square Wave - Current Offset

Figure 5

Comparison of offset vs normal balanced wave

DC+		SW AC with Offset
		AC 25% Balance
		(-)10% Offset
	Figure 6

		Square Wave	SW AC	SW AC	SW AC
Mode				25% Balanced	25% Balanced
	DC+	Balanced	25% Balanced	(-) 10% Offset	(-) 20% Offset
Penetration-mm	5.53	4.06	4.06	4.02	4.43

Figure 7

Penetration vs. Various Modes

All welds made using 5/32” (4mm) Diameter Electrode

525 Amperes, 31 Volts, 1.25” (31.8mm) ESO

18 ipm (457.2mm/min) Travel Speed

54.25 Kj Heat Input

T h e f u t u r e o f w e l d i n g i s h e r e . ®