Different Types Of Welding Processes
The art of welding has been in existence for decades. A process of heating certain materials - usually metals - in order to join them together, welding involves the application of heat and pressure to the two metals being joined, in addition to a filler material, with the goal of creating a weld pool that ultimately cools to form a strong, seamless joint.
Over the years, welding has changed and evolved with advancements in technology. Nevertheless, it’s imperative that would-be welders comprehend the differences in the various types of welding processes. Once they do understand the different types of welding techniques, they will be able to make an educated decision in terms of what type of welding process is appropriate for specific types of welding jobs.
There are currently several different types of welding processes in existence. These processes can be broken down into several general categories, including Arc Welding, Gas Welding, Resistance Welding and Energy Beam Welding. These processes all require different types of machinery to execute the welding process. There are some units around that can cope with several methods of welding procedures, such as the Rebel EMP 215ic from ESAB.
In the following article we will briefly discuss and define each of these techniques in some detail, highlighting the similarities and differences between each of the processes.
Arc Welding is a metal joining process in which the two materials being joined—usually metals—are heated at the point in which they come together with a continuous arc until they are melted, cooled and ultimately coalesced—or joined. The process involves the use of a power supply and electrodes to produce the “arc,” thus the name Arc Welding.
The most widely used welding process in existence today, Arc Welding comprises many of the most popular forms of welding (explained in detail below) - such as Stick Welding, MIG Welding and TIG Welding. The process known as Arc welding is a general category that includes two different types of welding sub-categories: the consumable electrode methods and the non-consumable electrode methods.
The category under the Arc Welding umbrella known as the Consumable Electrode Methods are the processes known familiarly as Stick Welding, MIG Welding, Flux-Cored Arc Welding, and Submerged Arc Welding. While the Non-Consumable Electrode Methods include the processes known as TIG Welding, Electroslag Welding, Atomic Hydrogen Welding, Carbon Arc Welding, and Electrogas Welding. Below we will briefly define all of these Arc Welding techniques.
Arc Welding: Consumable Electrode Methods
Although fairly outdated these days, particularly when compared side by side with the processes of MIG and TIG welding, Stick Welding, also known as “Shielded Metal Arc Welding or SMAW,” is a welding process that uses a consumable electrode that is coated by what is known as flux—a material that is used to fill or “lay” the weld.
The technique is known as stick welding because it relies on the flux and the filler material called sticks or rods to make the weld. The flux is utilized to protect the hot, molten metal of the weld, while the stick or rods of filler material are heated to coalesce the two pieces of metal together.
Another, much more popular of the Arc welding processes, MIG welding, also known as “Gas Metal Arc Welding or GMAW) is a technique in which the electric current is provided by the filler metal wire. This filler metal wire, which is ultimately cooled and shielded from the air by a stream of chemically inert gas, helps to prevent oxidation from invading the weld joint.
Second only to TIG welding in terms of popularity, MIG welding is essentially a process that combines two metal materials together using a wire that is connected to an electrode current. The wire then passes through the welding stick, which is shielded from the outside air by an inert gas of some type.
Flux-Cored Arc Welding
The process known as Flux-Cored Arc Welding, or FCAW, is very similar to MIG welding. This technique, in which a shielding gas is not always needed (as it is with MIG welding), utilizes a specialized tubular-shaped wire filled with flux instead of a stick. FCAW is popular among beginning welders because it is affordable and very easy to learn, but there are some downsides. In Flux-Cored Arc Welding there are some limits in terms of its applications—jobs it can used on—and the end result of the weld is not very aesthetically pleasing. It is, however, a very versatile type of welding, due largely to the many different types of fillers that can be used to get the job done.
Submerged Arc Welding
Submerged Arc Welding, or SAW, was developed in 1935 by a group of welders known as Jones, Kennedy and Rothermund. This process, which is used mostly on ferrous steel and nickel-based metals, involves welding under a blanket of granular fusible flux—a filler material that consists of calcium, lime, fluoride, silica and manganese oxides among other substances. SAW is a popular form of welding in some settings because it produces fewer emissions and arc lights, making it much safer than other forms of welding. SAW also results in a deep weld penetration, and involves very little preparation compared to other methods, making it very rapid and efficient.
Arc Welding: Non-Consumable Electrode Methods
The most popular form of welding in existence today, TIG welding, or “Gas Tungsten Arc Welding (GTAW),” is a non-consumable electrode technique that is notable for relying on a non-consumable tungsten electrode, along with an inert gas (usually argon). Tungsten is a very hard and difficult to find metal that offers high purity and a great-looking weld that truly lasts.
In TIG welding, the heat needed to create the weld pool is generated by running an electric current through a tungsten electrode. This in turn creates an arc that is used to melt a metal wire, which will ultimately be used to join the two pieces of metal together.
Developed in the 1950s, Electroslag welding, or ESW, is a welding process in which the heat is generated and transferred via a layer of electro-conductive slag, through which electric current is passed. The process is a very efficient, single-pass welding technique that is typically used on very thick non-ferrous metals. ESW requires a lot of skill to master, and is a very popular technique in both the aerospace and maritime industries.
Atomic Hydrogen Welding
Although mostly being replaced by TIG Welding today, the older welding process known as Atomic Hydrogen Welding, or AHW, involves the placement of two metal tungsten electrodes in a hydrogen atmosphere, leading to a breaking up of the hydrogen molecules, which ultimately rejoin in an explosion of heat that can reach temperatures of up to 3,000 degrees Celsius or more.
AHW was invented by a man named Irving Langmuir. It is still very popular among a certain class of welders because it creates a very strong and cohesive weld without damaging the metal.
Carbon Arc Welding
Carbon Arc Welding, or CAW, is a welding technique that joins two metals together by heating them with an arc between a non-consumable carbon (graphite) electrode and the work-piece to which the weld is being added. Developed in 1881 by Nikolay Benardos and Stanislaw Olszewski, CAW was the first arc-welding process ever developed, but it is not used for many applications today, having been replaced by twin-carbon-arc welding and other variations.
CAW produces temperatures in excess of 3,000 °C. At this temperature the separate metals form a bond and become welded together.
Electrogas welding, or EGW, is a process that is similar to Electroslag welding in that the work-piece is struck with a consumable electrode, without the use of pressure. Invented in 1961, EGW involves an arc that is not extinguished, and remains struck during the process. The process is used regularly in the storage tank and shipbuilding industries.
As you can see, there are several different types of Arc Welding Processes—the most popular form of welding in existence. In addition to Arc Welding, there are a handful of other types of welding techniques, which we will briefly define below.
Gas Welding is a category of welding that relies on one or more gas flames, usually oxygen and acetylene, to join two metals at their ends, with or without the use of a filler material. Gas Welding, which was first developed in 1903 in France by the engineers Edmond Fouché and Charles Picard, is also known as Oxyfuel Welding—a process that can create heat up to and above 3,000 degrees Celsius.
Gas Welding is still a very popular process that is used in pipe and tube welding, and in certain repair industries.
Resistance Welding, also known as Electric Resistance Welding, is a type of electric pressure welding in which the required heat is generated by a stream of electric current through the different parts to be welded. It also requires sufficient pressure to go along with the flow of current.
Energy Beam Welding
Energy Beam Welding, or EBW, is a welding process that is conducted in a total vacuum. The technique involves the firing of a beam of high-velocity electrons at the two pieces of metal to be joined. The action or energy of the electrons quickly turns into heat to create the weld pool that ultimately joins the metals, allowing them to fuse together and create a tight seamless bond.