Gas Metal Arc Welding or Metal Inert Gas (MIG) Welding

 Gas Metal Arc Welding is a welding process that uses a continuously-fed wire electrode, a shielding gas, and an electric arc to join two metal pieces together. The shielding gas protects the weld from atmospheric contamination and helps to stabilize the arc. GMAW is commonly used in industries such as automotive, manufacturing, and construction for its ability to produce high-quality welds quickly and efficiently.

It's also known as Metal Inert Gas (MIG) welding.

PROCESS:

    It works by using a welding gun to feed a continuous consumable wire electrode from a spool into the weld joint. The wire electrode is typically made of steel or aluminium and is fed through a wire feeder mechanism. The welding gun also has a nozzle that directs a shielding gas, typically a mixture of argon and carbon dioxide, onto the weld pool to protect it from atmospheric contamination.

 

When the welding gun trigger is pulled, an electric arc is created between the wire electrode and the base metal. The heat from the arc melts the wire electrode and the base metal, which then fuse together to form the weld. The shielding gas protects the molten metal from oxidation and other atmospheric contaminants, which can weaken the weld or cause defects.

As the welding gun moves along the joint, the wire electrode is continuously fed into the weld pool, forming a solid, continuous weld bead. GMAW is a versatile welding process that can be used with a variety of base metals and thicknesses, making it a popular choice in many industrial applications.

INERT GAS:

Inert gas, also known as noble gas, is a group of chemical elements that are very stable and have very low reactivity with other elements. The six noble gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).

In summary, inert gases are important chemical elements that have low reactivity and are used in a wide range of applications, including lighting, welding, cooling, and analytical chemistry.

Argon and helium are the two most commonly used inert gases for MIG (metal inert gas) welding.

Argon is generally used as the primary gas for MIG welding of non-ferrous metals, such as aluminium and copper. It provides excellent arc stability and produces a smooth, consistent weld. Argon is also relatively inexpensive and readily available, making it a popular choice for MIG welding.

Helium, on the other hand, is used primarily for MIG welding of stainless steel and other high-alloy materials. It has a higher heat input than argon, which helps to produce deeper weld penetration and faster welding speeds. However, helium is more expensive than argon and can be more difficult to obtain.

Some welders also use a mixture of argon and helium, known as a "tri-mix," for MIG welding of certain materials. The proportions of the gases in the mixture can be adjusted to achieve the desired welding characteristics. For example, a tri-mix with higher helium content may be used for welding thicker materials, while a tri-mix with higher argon content may be used for welding thinner materials.

In summary, argon and helium are the most commonly used inert gases for MIG welding, with argon being preferred for non-ferrous metals and helium for high-alloy materials. Tri-mixes may also be used to achieve specific welding characteristics.

PROS:

     A.  Speed: MIG welding is a fast welding process as it uses a continuous wire feed, making it possible to weld continuously without stopping to change electrodes.

     B.  Versatility: MIG welding can be used on a wide range of materials, including stainless steel, mild steel, and aluminium.

     C.  Efficiency: MIG welding is an efficient welding process as it produces little waste, has a high deposition rate, and requires minimal clean up after welding.

     D.  Ease of use: MIG welding is relatively easy to learn and use, making it a popular choice for DIY and hobbyist welders.

CONS:

     A.  Cost: MIG welding requires a welding machine, a wire feeder, and a gas cylinder, making it a more expensive option than other welding processes.

     B.  Limited penetration: MIG welding has limited penetration capabilities, making it unsuitable for welding thicker materials.

     C.  Flux contamination: If the shielding gas is not used properly, the weld can be contaminated with flux, which can lead to porosity in the weld.

APPLICATIONS:

     1.    MIG welding is commonly used in industries such as automotive, construction, and            manufacturing.

     2.    It is suitable for welding thin to medium-thickness metals, making it a popular choice for     welding automotive parts, pipelines, and machinery.

     3.    MIG welding is also used in DIY projects and hobbyist welding due to its ease of use and     versatility.