Every MIG machine in every shop has a chart printed on the door — and it is usually close enough to get you in the ballpark. These charts go one step further and explain why the numbers sit where they do, so you can adjust deliberately instead of by feel. The two numbers that control everything are wire feed speed (the amps) and voltage (the arc length).
UNDERSTAND THE TWO SETTINGS
Wire feed speed controls amperage. Push more wire and the machine pushes more current to melt it. Voltage controls arc length: more voltage, longer arc, wider puddle, more heat into the part. The weld's character comes from the ratio. Wire too hot for the voltage gives you a ropey, narrow bead. Voltage too high for the wire speed sputters and sprays.
SHORT-CIRCUIT TRANSFER (THIN TO MEDIUM)
Short-circuit transfer runs low wire speed and low voltage — the wire dips into the puddle and "shorts" dozens of times per second. It is the forgiving mode for sheet metal, root passes, and out-of-position work. Use 75/25 argon/CO2.
| Wire | Thickness | Wire Speed (IPM) | Voltage | Gas (CFH) |
|---|---|---|---|---|
| 0.023" | 24 ga – 1/16" | 200–280 | 15–17 | 15–20 |
| 0.030" | 1/16" – 1/8" | 180–260 | 16–18 | 20–25 |
| 0.035" | 1/8" – 1/4" | 160–240 | 17–20 | 20–25 |
With 0.035" wire, roughly 100 IPM per 100 amps is a decent mental rule for short-circuit MIG.
SPRAY TRANSFER (MEDIUM TO HEAVY)
Above ~180–200 amps with the right gas, the arc changes character: the wire transfers as a fine spray of droplets and the arc gets a hissing, crackling sound. Spray runs hot and flat — it is a flat-position workhorse, not an out-of-position process. It needs a high-argon mix; 90/10 or 85/15 argon/CO2 is the standard for steel.
| Wire | Thickness | Wire Speed (IPM) | Voltage | Gas (CFH) |
|---|---|---|---|---|
| 0.035" | 3/16" – 1/4" | 260–340 | 21–23 | 30–35 |
| 0.045" | 1/4" – 3/8" | 220–300 | 22–24 | 30–40 |
| 0.052" | 3/8" – 1/2" | 200–280 | 23–25 | 35–45 |
Once you reach spray, the difference between a good and a bad setting shows up in the bead profile: a clean spray weld lays flat with a smooth crown. Rope means the wire is hot; a wide, dirty bead means the voltage is too high.
Change one setting at a time. If the weld is ropey, drop the wire speed 10% before touching voltage. If it sputters at the arc start, trim the voltage down 0.5–1V first — most "machines that hate me" are just 0.5V too hot.
GUN ANGLE AND STICKOUT
Parameters only work if the gun is where the chart assumes it is. Push angle 5–15° for flat and horizontal work. Keep contact tip-to-work distance (stickout) at about 3/8" — the numbers on these charts assume it. Too short and the puddle runs ahead; too long and the wire stubs into the puddle with spatter.
QUICK TROUBLESHOOTING
- Spatter everywhere — voltage too low for the wire speed, or the stickout is too long. Raise voltage 0.5–1V or slow the wire 5–10%.
- Burnback — wire speed too slow for the voltage, or a worn contact tip. Check the tip first; tips are cheaper than spools.
- Porosity — gas issues: flow too high or too low, draft, a loose gas fitting, or a half-empty cylinder. Check the fan first — gas and dirt are the usual suspects.
- Cold, rounded bead — not enough heat into the joint. Raise voltage before amps; the width of the bead is voltage.
Do not chase porosity by cranking the gas. Above ~40 CFH the flow becomes turbulent and pulls air in. Fix leaks, drafts, and nozzle blockage first.
THE BOTTOM LINE
MIG tuning is a two-knob system: wire speed sets the amps, voltage sets the arc. Start on the chart, change one knob at a time, and let the bead profile tell you which way to go. Every shop has its favorite wire and gas mix — but the numbers on these charts will get you within a few clicks of a good weld on the first pass.