Welding is the process of joining two metals together by melting the two materials and adding a filler material that forms a pool of molten metal between the connecting surfaces. There are four main types of welding and each is used for specific metals and bonds.
MIG stands for metal inert gas. It is the quickest and easiest way to weld, and has the ability to weld a large variety of metals and metal thicknesses. MIG welding machines, or ‘wire feed welders’, utilize a wire feed system that supplies a steady filler metal as its being used. The wire electrode being fed off of a spool inside the machine and through the handgun by two driving wheels is delivered to the weld with inert gas; the gas mixture protects the weld from contamination. The electrode melts the surfaces of the two materials and adds the filler metal to the pool that bonds the two surfaces.
TIG, or Tungsten inert gas, is a lot like MIG welding because it uses an electrode to create the arc and inert gas to protect the weld. However the filler material is manually added to the weld pool. The Tungsten electrode in the welding gun is sharpened to a point and kept about a fraction of an inch away from the actual weld and an arc heats the metal. As a molten metal begins to pool, filler is typically applied by dabbing the weld with the wire. Advantages include the ability to weld a larger variety of materials and a higher quality weld. A disadvantage to TIG welding is that it can take significantly longer and requires more operator skill.
Shielded metal arc welding is commonly referred to as stick welding. An electrode rod at the end of the welding gun is used to pass the electric current that creates the arc between the metal surfaces. The rod itself is the filler material as well as flux. The flux protects the weld area by producing Carbon Dioxide during the weld. This process is used to weld, is very versatile and inexpensive but it takes the most time. The rods are replaced fairly often and the excess flux must be chipped away after the weld is complete.
Gas welding consists of mixing Oxygen and Acetylene gas to create a flame torch capable of melting steels. It is the oldest and most versatile method of welding, but in recent years has become less popular in industrial applications. It is used primarily for pipes, tubes, and repair work. The equipment is simple and inexpensive. The flame is less concentrated than an electrical arc and causes a slower cooling process. This can lead to weld distortion and greater residual stress, but makes joining high alloy steels easier. Gas welding is very much like the process of oxyfuel cutting, when the same equipment is used to cut metal.
Article written by: Alex Fahl