Welding Processes
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The American Welding Society (AWS) classifies more than 90 different welding processes with even more variations. Those processes range from Oxygen-Fuel Gas Welding (OFW) to more common arc welding processes such as GMAW (MIG), GTAW (TIG) and SMAW (STICK). Of course, advanced processes such as Laser Welding, Friction Stir Welding, Explosion Welding, Ultrasonic Welding and more are also included in the classification. Here is an introduction to the most common welding processes: Oxy-fuel, MIG, TIG and STICK.
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Oxy-Fuel Gas Welding
Oxy-Fuel Gas Welding (OFW) is one of the oldest modern welding processes and it involves using a fuel gas mixture combined with oxygen to create a high energy flame that can be used as a heat source for welding, soldering, brazing and even cutting metals.
OFW was developed in the late 1800's as a significant improvement to traditional forging which had been used for centuries. The use of high-potential fuel gases and the addition of oxygen eliminated the need for intense pressure to cause a coalescence or joining of metals. While predominantly used on steel, OFW can be used to weld, solder, or braze different metals and alloys. However, it should be noted that weld quality can be marginal due to the lack of atmospheric shielding by the process. In short, there is nothing to block the oxygen and nitrogen from the surrounding air and no arc shielding is provided. |
SMAW: Shielded Metal Arc Welding (a.k.a. STICK welding)
Shielded Metal Arc Welding (SMAW) is one of the oldest modern processes and it was developed in the late 1800's along with OFW. Initially, the process used direct current (DC) and a bare electrode - which carried the welding current and added filler metal to the weld joint.
Early developments in SMAW found that using a flux to shield the arc and weld from the atmosphere drastically improved weld quality. Today, all SMAW electrodes are coated with a flux that melts with the arc to form a slag coating on top of the deposited weld. This slag coating protects the weld from atmospheric contamination and helps to preserve the mechanical and chemical properties of the weld. SMAW is widely used today because of it's simplicity, versatility and ability to produce high quality weldments. However, a low operator factor and low deposition efficiency often make other processes more productive and profitable. |
GMAW: Gas Metal Arc Welding (a.k.a. MIG welding)
Gas Metal Arc Welding (GMAW) is often referred to as MIG welding, which stands for Metal Inert Gas. However, the use of non-inert or active gases in the process make the term MIG technically incorrect.
This process is much more efficient than SMAW and it uses a long, continuously fed filler metal electrode that is in the form of a wire. Externally supplied shielding gas is used to protect the weld from the atmosphere and preserve mechanical and chemical properties. Developed in the 1920's and commercialized in 1948, GMAW is one of the most popular processes for welding metal. It's versatile and can weld almost all commercially important metals, it generates no flux or slag and results in a high operator factor because there is little need to stop welding and change the electrode. A variation or "sister" process to GMAW is FCAW - or Flux Cored Arc Welding which uses a tubular wire electrode that contains flux for added shielding. |
GTAW: Gas-Tungsten Arc Welding (a.k.a. TIG welding)
Gas Tungsten Arc Welding (GTAW) is often referred to as TIG or Tungsten Inert Gas Welding. But, like GMAW or MIG welding - the process doesn't always use an inert gas, so that term is technically incorrect.
This process uses a non-consumable tungsten electrode and filler metal is added by hand or using a non-integrated wire feeder directly to the weld pool. Advantages include pin-point control of the arc, no flux, no slag, no sparks and no spatter - which make it the cleanest arc welding process available. GTAW was also developed in the 1920's and commercialized in the 1940's. Early developments substituted Argon gas for Helium due to lower cost, greater availability and better arc stability. GTAW is capable of welding more metals and metal alloys than any other process. It is often used for high quality or high purity welds in markets such as aerospace, food processing and tool & die welding. |