Demand for welding professionals is expected to rise 8% from 2020 to 2030. With the rising need for metal products, skilled welders are more important than ever.

With such a need for welding services, you may be wondering what welding is. And how does welding work?

As it turns out, there are several kinds of welding and they all work slightly differently. If you have questions about welding, we’ve got you covered.

Read on to learn everything you need to know about how welding works!

What Is Welding?

Welding is the process of joining two pieces of metal together using high temperatures. Unlike soldering, welding completely fuses two pieces instead of just bonding them with melted solder wire.

Most often, the heat used to join metal parts comes from an electrical current. We call this type of welding “arc welding,” with “arc” referring to the arc of electricity.

Other less common methods of welding use gas flames or even lasers to heat metal components.

How Does Welding Work?

All arc welding processes share a few main parts. These are the power source, electrode, filler metal, and shielding gas.

To explain simply how arc welding works, we’ll use the example of a car battery.

If you’ve ever had to jumpstart a car, you know that the battery has a negative end and a positive end. When you hook up jumper cables to the battery and touch the clamps together, it results in sparks.

You shouldn’t touch jumper cables together while jumpstarting a car, as it can cause overheating and other hazards. However, it’s a useful example of an electrical arc.

With welding, either the positive or negative end of the power source is connected to the base metal, with the other connected to the electrode. When the electrode makes contact with the base metal, it produces an arc that heats the metal enough to melt it.

While the metal is hot enough to melt, the filler metal feeds into the weld to build it up. Think of hot glue being fed out of a glue gun to join materials together.

This is where the shielding gas comes in. If the metal is exposed to the air while welding, it will result in tiny bubbles, called porosity, that will weaken the weld.

Shielding gas, usually a mixture of argon and some other gas, keeps air out of the weld and helps keep the weld uniform.

What Is a Welder?

The welding field has a wide variety of professionals with diverse skills and expertise. The American Welding Society defines a welding professional as any of the following:

  • Boilermakers
  • Sheet metal workers
  • Structural iron and steel workers
  • Structural metal fabricators and fitters
  • Welding, soldering, and brazing machine setters, operators, and tenders
  • Welders, cutters, solderers, and brazers

Types of Welding Processes

Now that we know the basic components of welding, let’s take a look at the common types of welding and what they’re used for. There are four primary arc welding processes: stick, MIG, TIG, and flux core.

In most production facilities, welders work with steel materials, but any metal is weldable. Other metals commonly used in welding include cast iron and aluminum.

SMAW: Stick Welding

SMAW stands for shielded metal arc welding and is usually called stick welding. Stick is the oldest arc welding process and remains in use today.

The main advantage of stick welding is the simplicity of the equipment. Unlike other arc welding processes, stick welding doesn’t require a gas cylinder, making it useful for field welding.

In stick welding, the electrode, filler metal, and shielding gas are all contained in a consumable welding rod. Stick welding is called stick welding because of this rod. The welding rod is coated with a material called flux which produces shielding gas when heated.

As the rod heats the base metal, it also melts to fill in the weld. The welder pushes the rod into the weld as it becomes shorter.

While stick welding offers advantages like simplicity and portability, it is a time-consuming and labor-intensive process. The most common applications for stick welding are structural welding and building construction.

GMAW: MIG Welding

GMAW stands for gas metal arc welding. MIG, or metal inert gas, is the more common name for this process.

In MIG, the welder uses a gun assembly to feed filler wire from a spool gun into the weld. Since the machine feeds filler metal into the weld continuously when the welder pulls the trigger, MIG is considered an automatic process.

In addition to feeding wire, the gun is also connected to a hose that forces shielding gas onto the weld. The shielding gas used with MIG is usually a mixture of argon and Co2.

While MIG is generally easier to perform than other processes, getting all the settings correct requires some technical knowledge. MIG settings include wire feed speed, voltage, and gas flow.

MIG is easy to learn and produces welds quickly, making it useful for mass production. You almost certainly have something in your home that was welded using MIG.

However, MIG welds are not as strong as those of other processes and can break easily if performed haphazardly.

MIG is mostly used for light fabrication, automotive welding, and production welding

GTAW: TIG Welding

GTAW stands for gas tungsten arc welding. Most welders call this welding process TIG, which stands for tungsten inert gas.

TIG is usually considered the most difficult welding process requiring the most skill. Unlike the other processes, TIG uses one hand to control the electrode, and another to manually feed filler metal into the weld.

The electrode in TIG welding is a tungsten needle ground to a pointed or rounded end housed in a gun which also emits shielding gas. To channel the shielding gas onto the weld, TIG guns have a heat-resistant ceramic cup that surrounds the tungsten needle.

The welder manipulates the arc of electricity by moving the gun in a controlled pattern. Meanwhile, the other hand pushes a length of solid metal wire into the weld pool.

Because TIG requires the most skill to monitor welds for quality, this type of welder is usually the highest-paid.

While TIG produces clean and aesthetically pleasing welds, it is the slowest welding process requiring the most time. TIG is most commonly used for sanitary welds, such as pipes and food processing facilities.

FCAW: Flux Core Welding

FCAW stands for flux core arc welding. However, most welding professionals simply say, “flux core.”

Flux core is similar to MIG. It uses a spool of wire that feeds into the weld through a gun assembly that activates with a trigger pull.

The main difference between MIG and flux core is the type of wire. As the name suggests, flux core uses a wire containing flux, the same material coating SMAW welding rods.

Because the wire contains flux, it isn’t always necessary to use a gas cylinder with flux core welding. When flux core is used with shielding gas, it is referred to as “dual-shielded flux core.”

Flux core penetrates deeply and produces welds quickly, making it a good substitute for stick welding in commercial applications. Its strong bond is useful for structural welding and aerospace applications.

OAW: Oxy-Acetylene Welding

Oxy-acetylene, or oxyfuel, welding is not a form of arc welding and uses no electricity. Rather, a combination of oxygen and some fuel gas, most commonly acetylene, is forced into a torch and ignited to create a flame.

Gas welding is the oldest form of welding, dating back to the early 19th century. When arc welding became commonplace in the 20th century, oxyfuel welding became obsolete for most commercial purposes.

Some welding schools still teach beginner students to use oxyfuel welding, since it’s easy to control the weld. It’s also still useful for automotive welding since arc welding can cause electrical issues with a car if proper precautions aren’t taken.

Artists and metal sculptors also commonly use oxyfuel welding since the equipment is relatively inexpensive and easy to use.

Laser Welding

Another less common type of welding uses a focused light beam to heat metal components. Unlike regular light, the light particles of a laser don’t spread out, allowing them to produce a focused heat source.

Laser welds are generally performed by robotic machinery. This type of weld is very precise and fast but has high operating costs.

Common applications of laser welding include mass-produced automotive and roofing parts, as well as smaller items like jewelry.

In addition to welding, laser machinery is also commonly used for making precise and complex cuts. Laser cutting can quickly and efficiently produce highly accurate metal pieces.

How to Check a Weld

In welding, any issue with the weld that affects its quality or strength is called a defect or discontinuity. There are several different kinds of weld defects, each having unique causes.

Look for these problems when inspecting a weld.


Probably the most common issue with welds, porosity is the result of air getting into the weld. While we know a lack of shielding gas causes porosity, a number of mistakes can result in this defect.

If the electrode is too far from the weld, shielding gas may not cover it. Additionally, an improper angle or windy conditions can cause porosity.

Incomplete Fusion

This defect is just what it sounds like. Any time two components aren’t completely joined together, they have incomplete fusion.

You can identify incomplete fusion by the appearance of a seam between the weld and the base metal.

Incomplete fusion has a few potential causes. If the welder moved too fast, the material may not have had time to fully fuse. Additionally, a weld completed without enough current may have incomplete fusion.


Undercut occurs when the heat of the weld removes base metal without filling it in with weld. The result is the appearance of a depressed groove along the weld that can affect its strength.

Welders get undercut when they weld too fast or have their current set too high.


In welding, spatter refers to small droplets of metal being left on the finished product. Excessive spatter will result in a “bumpy” appearance.

While some spatter is normal, excessive spatter can come from the electrode being too far from the base metal during welding. It’s also possible there wasn’t enough shielding gas covering the weld.

What Is Cold Welding?

Sometimes you can join metal components without using heat. Cold welding is the process of fusing metal parts together using extreme pressure.

By removing oxide coatings on metal parts and pressing them together, the pieces become joined at the molecular level. Similar to how you could join two pieces of clay by pressing them together, this process eliminates the separation between materials without using heat.

While it may not seem like it, cold welding can actually form a bond just as strong as arc or gas welding. It offers several advantages over welding processes that use heat.

First, the lack of heat reduces the warping of the base metal. Additionally, cold welding can be used to join two different metals, which can be difficult with arc welding.

Cold welding has a few applications, such as joining wires and aerospace equipment. Astronauts even use cold pressure welding in space for satellite repairs.

The Bottom Line on Welding

We hope you found this article informative and helpful! There are so many types of welding that it’s easy to find yourself wondering, “how does welding work?”

Essentially, the electrode channels an electrical current and connects to the oppositely charged base metal to produce an arc. The arc heats the metal while a filler metal feeds into the weld.

Shielding gas protects the weld from the air. This protective gas comes either from a cylinder or a solid material called flux.

In addition to welding, our facility offers laser etching and cutting, custom fabrication, design, and engineering. No matter what your metal fabrication needs, we can help.

Contact us today to find out more about our metal services!


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