Types of Welding Processes: A Detailed Guide
by Rob Goldiez, on Sep 9, 2021 3:30:00 PM
Welding built the world we live in - from our houses, buildings, cars, bridges, and even spaceships. Are you curious about welding and want to learn more about it? Do you want to know about the different welding processes? Or what do the welding acronyms GMAW, GTAW, SMAW stand for? You’ve come to the right place.
In this article, let’s discuss:
(Click on a title to jump to the section!)
- What is Welding?
- What are The 4 Main Types of Welding?
- What Are The Other Types of Welding Processes
- Want To Know More About Welding?
What is Welding?
Welding in its very basic form is the joining of two metals through heat or pressure. It’s an ancient process that dates back as far as the iron age. During that time, our ancestors hammered two metals together using heat. All the welding equipment and techniques that we see today started during the Industrial revolution. Since then, the welding process has long since progressed. Now, there are different types of welding processes used depending on other factors. These factors can take the form of:
- Type of metal welded - aluminum, copper, steel etc.
- The thickness of the metal
- The welding environment ( inside, outside, underwater, etc.)
- Where the final product is going to be used - hospital, automotive, aerospace, etc.
The welding industry is made even more exciting with its shift to automation, but that is for another article.
What Are the 4 Main Types of Welding?
There are many types of welding depending on how you want to use it. But of these, four common ones are widely used in the welding industry. These are:
- Gas Metal Arc Welding (GMAW or MIG)
- Gas Tungsten Arc Welding (GTAW or TIG)
- Shielded Metal Arc Welding
- Flux Cored Arc Welding
These types of welding join two metal parts with the assistance of an electric arc. This electric arc is formed between the metal part and an electrode on the gun.
Gas Metal Arc Welding (GMAW or MIG)
Gas Metal Arc Welding (GMAW) is also popularly called Metal Inert Gas Welding (MIG) among welders.
In this welding process, the electrode also acts as the filler metal to create the weld. It is constantly fed through the welding gun as it melts. MIG also uses shielding gas that comes in the form of carbon dioxide, oxygen, helium, or argon. This gas traveling through the welding gun is essential. This gas helps protect the molten pool of metal from environmental contaminants that can affect the quality of the weld.
GMAW is the most accessible type of welding to master. And it is often used for welding stainless steel, copper, nickel, carbon steel, and aluminum. This type of welding is also best for lower volume work, usually found in medium welding businesses.
Advantages of Gas Metal Arc Welding
GMAW is popular and can join metals of different thicknesses. It’s easy to learn and master. And the components needed for anyone to start welding are readily available in the market.
Moreover, Gas Metal Arc Welding can be easily automated with Cobots like the Cobot Welder from Hirebotics. The Cobot welder is a robotic arm with a welding torch at the end of the arm built to work alongside welders. It can be deployed on the factory floor to help automate the monotonous parts of welding. It’s also the easiest cobot in the market to program - you can teach it through a phone or tablet application!
Limitations of Gas Metal Arc Welding
With GMAW, you always need a bottle of gas for shielding. And depending on what gas you use, it can be expensive. The positions you can weld with GMAW are also limited. You can’t use this type of welding process overhead or vertically. In addition, you can’t use the GMAW process outdoors because elemental factors like wind can adversely affect it.
Gas Tungsten Arc Welding (GTAW or TIG)
Of all the welding techniques, Gas Tungsten Arc Welding (GTAW) is the most versatile. People in the welding industry also call this type of welding Tungsten Inert Gas Welding (TIG)
As its name indicates, this type of welding uses a tungsten electrode. This electrode is what gives current to the welding arc. Like GMAW, Gas Tungsten Arc Welding uses gas shielding. It’s commonly used for welding aluminum and magnesium. Moreover, it can also be used to weld metals such as copper, copper alloys, and stainless steel.
Gas Tungsten Arc Welding produces precise and neat welds. This welding process found uses in industries like electronics, aerospace, automotive, repair, and even art.
Advantages of Gas Tungsten Arc Welding
Welds made from Gas Tungsten Arc Welding are very precise and have a neat appearance. The welds have a superior cosmetic appearance compared to other welds. That’s why people welding visible welds on products turn to GTAW because it looks aesthetically pleasing. The welds are also durable and of high quality. Gas tungsten arc welding can be used to weld a wide variety of metals, making this process a versatile one.
Limitations of Gas Tungsten Arc Welding
Gas Tungsten Arc Welding is complex and requires a great deal of expertise. Welders using this welding process use both hands. They use one hand to hold the torch and the other hand to hold the filler metal.
Most of the time, only experienced and educated welders can manage this type of welding in a production environment. And, although it produces strong welds, you have to be sure to work with clean metals as impurities can produce weaker welds. In GTAW you have to take extra care that the tungsten material doesn’t go to the molten weld or it can contaminate the welding pool.
Shielded Metal Arc Welding (SMAW)
Shielded Metal Arc Building (SMAW) is also called stick welding. It’s one of the earliest welding techniques developed and also one of the most common. In this type of welding, you’ll use a protected and consumable electrode (stick). This stick melts in the arc and becomes the filler metal to join the two metal parts. As the stick melts, it also emits a gas that protects the area to be welded. Construction, underwater pipelines, and industrial fabrication use this type of welding. You can use this type of welding to join steel, cast, ductile iron, nickel, or copper. However, it’s rarely used on aluminum.
Advantages of Shielded Metal Arc Welding
Unlike GMAW and GTAW, this type of welding doesn’t require gas shielding. It’s also portable so that you can weld anywhere. SMAW doesn’t need the metal to be free of impurities. So you can even use this type of welding process on rusty materials. You can also easily change the rods to adapt to different metals.
Limitations of Shielded Metal Arc Welding
This type of welding is advanced and needs skilled welders. It also produces a lot of waste from the materials used -mostly coming from the slag. The slag is the leftover material formed at the top of the welded metal. It’s also slower because you need to chip away the slag every time the rod is finished.
Flux Cored Arc Welding (FCAW)
Flux-Cored Arc Welding (FCAW) is similar to Gas Metal Arc Welding but can be performed without shielding gas. The difference lies in the electrode material. FCAW uses a flux-cored electrode as a filler material for the weld. Flux is a mix of silicate and carbonate material. Since its density is lighter than the welded material, it floats to the surface. The flux protects the metal being welded from contaminants from the atmosphere. FCAW is usually the welding technique used in bridge construction, shipbuilding, and heavy equipment repair.
Advantages of Flux Cored Arc Welding
Flux Cored Arc Welding has a heavy deposition rate. Depending on the electrode used, a welder can deposit anywhere from 3 pounds up to 20 pounds (9kg) of metal. It also has a more stable arc compared to other types of welding processes. Unlike GMAW, Flux Cored Arc Welding can be used outdoors without gas shielding. Moreover, the metal doesn’t have to undergo precleaning. You can also weld in any position with this type of welding process.
Limitations of Flux Cored Arc Welding
FCAW produces more smoke than other welding methods. Sometimes, the smoke is even carcinogenic. So if you want to do FCAW indoors, make sure that the area is well ventilated. The electrode used is also more expensive. In addition, the metals it can weld are limited to carbon and stainless steel, cast iron, and hard surfacing alloys.
What Are The Other Types of Welding Processes
The four that we’ve discussed above are the most common types of welding processes. But there are other welding processes that, while not so common, are also worth being familiar with.
- Electron Beam and Laser Welding
- Atomic Hydrogen Welding
- Thermit Welding
- Submerged Arc Welding (SAW)
- Plasma Arc Welding (PAW)
- Gas Welding/Oxyacetylene Welding
Electron Beam and Laser Welding
Electronic Beam and Laser Welding is a welding process where two metals are fused using a beam of high-velocity electrons or a laser. The welds made by this process are precise and very high quality. However, the welding process only takes place inside a special vacuum atmosphere. This vacuum environment is to make sure everything is stable for the electrons to do their job. Industries like aerospace and car manufacturing use this type of welding.
Atomic Hydrogen Welding
Atomic Hydrogen Welding (AHW) is a type of arc welding. It uses an arc between two electrodes made of tungsten with hydrogen gas. The electric arc in between the two electrodes breaks down the hydrogen molecules. The molecules later recombine and produce a very high amount of heat. This heat facilitates the welding process by fusing the two metals together. Nowadays, the GMAW welding process replaced AHW.
Thermite Welding or exothermic welding is a welding process that uses molten metal to permanently join the metals to be welded. The process needs thermite - a mixture of metal oxide and aluminum powder. The process is an exothermic reaction of the thermite composition that heats the metals and fuses them together. An external heat source is needed to ignite the thermite and start the chemical reaction. This type of welding is commonly used to weld cracks in railways and make heavy joints for large pieces of machinery.
Submerged Arc Welding (SAW)
The Submerged Arc Welding process is a type of arc welding. The formation of the arc is made from an electrode, acting as the filler material. The term submerged in Submerged Arc Welding (SAW) is because the weld zone is covered entirely with a layer of granulated flux. This flux is made from carbon and silicate material. The flux generates a gas shield and facilitates electrical conduction when molten. During the welding process, the flux is continuously delivered by a tube attached to a flux hopper.
The entire welding process is mechanized and is buried under the granular flux, so it can’t be seen from the outside.
This type of arc welding process can have a high metal deposition rate of up to 20 kg/hour. It also has a capacity for welding metals with thickness up to 100mm. This type of welding is often used in heavy fabrication industries. The aviation industry, shipbuilding, railroads, and bridge-building also use this type of welding.
Plasma Arc Welding (PAW)
Plasma Arc Welding or PAW is a type of arc welding similar to Gas Tungsten Arc Welding. The similarities lie in the arc created between a tungsten electrode and the object being welded. However, in PAW, the plasma arc is isolated from the shielding gas. Isolation is done by putting the electrode inside the torch’s body. The arc is also constrained by plasma pushed through a fine-bore copper nozzle. The electronics industry often uses this type of welding. It also found application in the aerospace industry.
Gas Welding/Oxyacetylene Welding
Gas Welding is also known as oxy acetylene-fuel welding or oxy welding for short. This type of welding process is a form of solvent-based fusion welding. This process involves a handheld torch that pumps out acetylene and oxygen—combining these two burns to form a flame that connects the surface of the two metals using oxygen as the fuel. The flame produced from combustion is scorching - more than 4500 degrees Fahrenheit. It’s more than enough to weld two metals together.
Welders usually use this welding technique to join thinner metals. These metals can be ferrous, non-ferrous metals, alloy steel, carbon steel, etc. Moreover, it found applications in the aircraft and automotive industries.
Want To Know More About Welding?
Welding and its different types is a fascinating topic. It can also be a lucrative and exciting career. Especially since there are lots of welding jobs to fill due to the welder shortage. In the meantime, to fill in the gap from the welder shortage, welding companies have turned to automation. Modern technology made the welding industry more interesting with the move to automation, either with welding machines or robotics.
The new technology used to automate welding are collaborative robots. Welding Cobots are changing the industry and helping SMEs with no robotics expertise to dive into welding automation.