A note on Gas Metal Arc Welding:
GMAW (gas metal arc welding) as recognized by the American Welding Society is also generally known as MIG (Metal Inert Gas) and uses a nonstop solid wire electrode for stuffing metal and an externally supplied gas (characteristically from a high-pressure cylinder) for shielding. The cable is generally mild steel, typically copper colored since it is electroplated with a slim layer of copper to defend it from rusting, get better electrical conductivity, increase contact tip life and usually improve arc performance. The welder has to be setup for DC positive polarity. The shielding gas, which is generally carbon dioxide or mixtures of carbon dioxide and argon, guards the molten metal from reacting with the atmosphere. Shielding gas flows through the gun and wire assembly and out the gun needle with the welding wire to shield and guard the molten weld pool. Molten metal is very reactive to oxygen, nitrogen and hydrogen from the atmosphere, if bare to it. The inert gas regularly continues to flow for some time following welding to keep protecting the metal as it cools. A small breeze can blow the shielding away and cause porosity, so welding outdoors is generally avoided if not particular windscreens are erected.
However, if completed correctly, operator appeal and weld appearances are brilliant with MIG and it is the majority welders' preferred process to use. Good method will yield brilliant results. The correctly made finished weld has no slag and virtually no spatter. A push gun angle is usually used to enhance gas coverage and get the finest results. If the material you are welding is unclean, rusty, or painted it must be cleaned by grinding until you see shiny bare metal. MIG welding can be used with all of the main commercial metals, including small carbon steel, low alloy steel, and stainless steel and aluminum with possible for brilliant achievement by a novice.