Common welding processes
As Steve mentioned in his video, the three most common welding processes are MIG, stick, and TIG. We are going to look at each of these processes in a bit more detail. So, let’s start with MIG.
MIG stands for Metal Inert Gas. This is a welding process in the category of Gas Metal Arc Welding (GMAW). MIG is a semi-automated welding process, which is widely used in many sectors of industry, such as shipbuilding, railroad construction and the production of heavy plants and machinery.
The MIG process melts and fuses metals by using the intense heat generated by an electric arc. This heat is applied between the metals to be joined and a filler wire (solid or flux cored). The wire is melted at the same speed at which it is being fed by the wire feeder. This forms part of the weld pool. Both the arc and the weld pool are protected against atmospheric contamination by a shield of inert (non-reactive) gas.
The filler metal is the electrode which is on a spool of wire. The advantage of a shielding gas process is that it is much easier to learn because you preset all of your parameters. It is much cleaner because you don’t have any kind of slag process and you can hit a wide variety of metal thicknesses.
Let’s look at the setup.
On the left you see a cross-section, and on the right you see a side-view of the process.
The process is supported by an array of equipment as seen in the illustration below.
Stick Welding, also known as Shielded Metal Arc Welding (SMAW), is the most widely-used arc welding processes. It uses an electrode and electric current to join a variety of metals. The electrode is made of a solid metal rod or “stick.” This is surrounded by a coating of compounds and metal powders with a binding agent to help them bind to its surface.
Electric current, either alternating current (AC) or direct current (DC), is used to make an electric arc between the electrode and the metals to be joined. The electrode conducts electric current to the arc and provides filler metal for the joint.
Stick Welding is one of the earliest and most popular welding processes because it is simple and can be used in a lot of different situations.
It is used primarily to weld iron and steel. It is also used extensively in the maintenance and repair industries and construction of heavy steel structures.
Stick Welding uses a flux-coated electrode to form the weld. The electric current passes through the coated electrode or welding rod and arcs at the point of contact with the base metal. As the electrode begins to melt, the flux coating around it creates a cloud of gases that shields the molten metal and prevents it from oxidizing. This is why it also called shielded metal arc welding. The gas cloud settles on the pool of molten metal as it cools and turns into slag. This slag must be chipped off after the welding is completed. Stick Welding a quite simple process and does not require a great deal of specialized equipment.
Because stick welding is a flux-based process, it works well outside. It is not affected by wind as much as other processes are. It works well on thicker metals. Another advantage is that it works well on dirty metals. If you work on farm equipment or a gate in your driveway, rust and debris do not affect stick welding as they do other welding processes.
A big disadvantage is that you get a lot of splatter, off-gassing and fumes. So be careful if you use a stick welding process indoors. One more disadvantage is the fact that you do not get the cleanest or pretties weld if you are working, for example, on an auto frame. In this case, you will probably want to use MIG or TIG.
TIG welding is another name for gas tungsten arc welding. The aircraft industry created it to weld magnesium in the 1930s and 1940s. In this process, the welder makes an arc between the base metal and the non-consumable tungsten electrode located in the welding torch. This type of electrode does not melt. At the point where the arc hits the base metal, a molten weld pool forms. Then a thin wire of filler metal is slowly handfed into the weld pool, where it melts. While this is happening, an inert shielding gas protects the tungsten electrode and weld pool from oxygen contamination. So, no fluxes are used. The finished product is a sound, slag-free weld with the same corrosion resistant properties as the parent metal.
Today, the TIG welding process is used to produce very high-quality welding especially in demanding sectors such as pressure vessels, pipelines, food industry containers, aviation, and the construction of spacecraft. TIG welding is especially suited to sheet materials with thicknesses up to about 8 or 10 mm. But, TIG welding can be used for more metals than any other type of process. For this reason, a variety of industries rely on TIG welding. Auto manufacturers use TIG welding on fenders because of its anti-corrosive properties.
One of the greatest advantages of TIG welding is the amount of control it allows the welder. A welder can control heat and amperage with precision by using a foot or thumb remote control switch. The TIG welder is also thin, which adds to the control a welder has over the process. As a result, TIG welding is good for projects where detailed designs or curves are required on the base metal. It is, however, the hardest welding process for a welder to master. The welder must be able to control all three elements in the process. The leg controls your heat, the opposite hand controls the filler metal deposition rate and then, of course, there is a non-consumable tungsten electrode that creates the arch as the welder moves through the bead.
Let’s look at the setup.
The equipment you need for TIG welding is as follows;
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