MIG Welding Gas Versus Flux Core

Basics

• An electric arc is a little like a sustained spark across an air gap. The high-voltage arc created by the welding gun causes the temperature to soar, melting the metal so it coalesces and forms a weld. The high temperature also has other, more undesirable consequences, because the metal can react with oxygen to make brittle oxides. These compounds weaken the weld. Both MIG and flux core welding use shielding to inhibit oxide formation.

Shielding

• In MIG welding, the shield is a nonreactive gas like argon. The gas creates a cloak around the weld and excludes air from its immediate vicinity until the metal has had time to cool. Flux core welding, by contrast, makes use of a hollow electrode with a core full of a material called flux. When heated to high temperatures, the flux reacts with oxygen and releases gases that shield the weld from the surrounding air.

Benefits of Flux Core

• The key difference between the two techniques is that in MIG, the shielding is external and supplied by gas from a cylinder, whereas in flux core welding, the shielding is supplied by the core of the electrode. MIG welding seldom can be done outdoors because the breeze can easily blow the inert gas away. Flux core welding, in contrast, does not have such limitations. Flux core also tends to be superior for thicker materials and requires less equipment.

Benefits of MIG

• If appearance is important or if you plan to finish and paint the surface, MIG welding tends to be superior, since flux welding creates more unsightly spattering and slag. MIG welding is easier to learn and somewhat more forgiving; flux core welding requires the settings to be chosen with much greater precision, which is difficult if you're just learning how to weld. MIG may also be suitable for a wider range of metals, like aluminum and nickel alloys, as long as you have the necessary know-how and the right equipment.