Wire Feed Speed and Voltage Relationships
MIG welding parameters must be balanced as a system — wire feed speed (WFS) and voltage are interdependent, and changing one without adjusting the other degrades weld quality. Wire feed speed directly controls amperage: increasing WFS increases current draw because the machine must melt more wire per second. As a starting point for 0.035" ER70S-6 wire on 1/4" carbon steel, set WFS at approximately 250–300 in/min and voltage at 19–21V for short-circuit transfer. For spray transfer on material 3/8" and thicker with 90/10 Ar/CO2, WFS increases to 350–450 in/min and voltage rises to 24–27V. The arc sound is your best diagnostic tool: a correct short-circuit transfer arc sounds like bacon frying — a steady, fast crackle. A voltage that is too high produces a loud, irregular popping with excessive spatter. Voltage too low causes a harsh, stuttering arc with the wire stubbing into the puddle. Listen and adjust in small increments (0.5–1V at a time). Stick-out — the distance from contact tip to work — also affects amperage: longer stick-out increases resistance in the wire, effectively reducing amperage even at the same WFS setting. Maintain consistent stick-out of 3/8" to 1/2" for 0.035" wire.