Welding Sheet Metal Mig. Suitable electrodes are E6011 for rusty or painted surfaces or E6013 for clean surfaces. The wire melts into the base metal providing the heat and some filler material as the wire melts.
When MIG welding sheet metal it is important to set the proper parameters to prevent warping and burn-through or else it will create excess heat and easily blowholes on the metal. Rod diameter shall be as thin as possible so 18 or 116 diameter electrodes are. Always use the smallest wire diameter possible since smaller wires take less heat to melt and heat the metal less.
Keep in mind during the welding process it is important to direct the arc right at the center of the weld puddle and dont do movements like whipping or weaving.
For thinner gauge sheet metal like 18 or 20 gauge we suggest 023 6mm wire in your MIG welder. You can also try the whipping method to reduce heat build-up. It is recommended that a welder should use 023- or 024-inch wire for light gauge sheet metal work. MIG welding sheet metal.