Wire Feed Speed — What It Is and Why It Matters
Wire feed speed (WFS, measured in inches per minute — IPM) is the rate at which the welding wire is fed from the spool through the MIG gun to the arc. In constant-voltage MIG welding, wire feed speed is the primary control for amperage — faster feed increases current; slower feed decreases it.
This relationship exists because the arc melts wire at a rate proportional to the current flowing through it. If you feed wire faster than the arc can melt it, the wire stubs into the pool and the power source automatically increases current to melt the excess. Feed slower, and the current drops. This self-regulating system is what makes MIG welding relatively easy to set up and use.
Typical wire feed speeds range from 100 IPM (thin material, low amperage) to 400+ IPM (thick material, high amperage production). Most MIG welders display either wire feed speed or amperage on the control panel — on machines that show only WFS, the operator dials the speed and the amperage follows automatically.
Frequently Asked Questions
How do I set the correct wire feed speed?
Start with the manufacturer's recommended settings for your wire diameter, material thickness, and gas type — these charts come with every MIG welder. Fine-tune by sound and bead appearance: a smooth, steady crackle indicates proper settings. A sputtery, erratic sound means the WFS and voltage are out of balance.
Does wire feed speed directly equal amperage?
In constant-voltage MIG welding, yes — there is a direct, roughly linear relationship between wire feed speed and amperage. The exact ratio depends on wire diameter, wire composition, and stick-out distance. This is why many modern MIG welders display amperage instead of WFS — they are effectively the same control.