October 31, 2026 · Indumor

MIG-MAG welding course · Appendix B← Previous

Starting values for carbon steel with ER70S-6 wire and an argon-CO₂ blend (M21), in the flat or horizontal position, with about 12 to 15 mm of contact tip to work distance in short-circuit and 18 to 20 mm in spray. They are a starting point: fine-tune them on a scrap plate of the same thickness and, when there is a procedure, the WPS rules.

Thickness	Joint	Wire (mm)	Wire feed speed, m/min (ipm)	Voltage (V)	Approx. current (A)	Transfer	Gas, L/min (CFH)
1 mm (20 ga)	Butt or fillet	0.8	3 to 4 (120 to 160)	15 to 16	60 to 80	Short-circuit	10 (21)
2 mm (14 ga)	Butt or fillet	0.8 or 1.0	3.5 to 4.5 (140 to 180)	16 to 18	90 to 110	Short-circuit	10 to 12 (21 to 25)
3 mm (1/8 in)	Fillet or gapped butt	1.0	4.5 to 6 (180 to 240)	17 to 19	110 to 140	Short-circuit	10 to 12 (21 to 25)
4 to 5 mm (3/16 in)	Fillet	1.0	6 to 8 (240 to 315)	19 to 21	140 to 180	Short-circuit	12 (25)
6 mm (1/4 in)	Fillet in PB (2F)	1.2	6 to 7 (240 to 275)	23 to 26	200 to 230	Globular to spray, depending on blend	12 to 15 (25 to 32)
8 to 10 mm (3/8 in)	Fillet or V, multipass	1.2	8 to 10 (315 to 395)	27 to 30	250 to 290	Spray	15 (32)
12 mm (1/2 in) and up	V or double V, multipass	1.2	9 to 12 (355 to 470)	28 to 32	270 to 320	Spray	15 to 18 (32 to 38)

How to use it

Start from the wire feed speed for the thickness and correct the voltage 1 V at a time until the arc sounds steady and the bead lies flat.
For vertical up and overhead, lower the wire feed speed by 10 to 20 %, or use pulsed transfer.
With straight CO₂, voltage usually runs 1 or 2 V higher and there is no spray: short-circuit up to about 6 mm and globular above that.
With 1.2 mm wire, spray appears from about 220 to 250 A with low-CO₂ blends; more CO₂ needs more current.
On thin sheet, if it burns through, lower the wire feed speed before the voltage, or weld in short sections.

Each column is explained in lesson 4, lesson 5 and lesson 8 of the course. The chart belongs to the Steel Knowledge Hub of Indumor; for section sizes and weights, see the technical tables.

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