How is a welding arc produced?

In welding, the electric current travels between the electrode and the ground, creating an arc. This process is essentially like a miniature lightning bolt. The purpose of the arc is to melt the base metals together, fusing them in a bond. As a result, part of the metal is consumed; therefore, a filler material is necessary to fill this void.

Simplifying welding in these terms makes it sound like an easy process. It is anything but. To learn more about how a welder produces a welding arc, keep reading!

Learning how a welding arc is produced puts you on the path to becoming an expert welder. Understanding how it all works will allow you to customize your welding experience and troubleshoot issues in order to achieve the welds you desire.

Welding in Context: Polarity

Before we delve too deep into the components a welding arc, let’s first discuss the idea of polarity. Because electricity flows between the electrode and the ground, both a positive and negative element are involved. Knowing the difference between these two flow types is crucial to proper welding techniques.

Electrode-Negative

When something is deemed “electrode-negative,” it means that the electrode is powered via the negative terminal on the welder/power source and electricity flows from the electrode to the ground and back to the power source via the positive lead. “Electrode-negative (straight polarity),” states Lincoln Electric’s article on understanding polarity, “results in faster melt-off of the electrode and, therefore, faster deposition rate.” Because the current is moving directly into the base metal, the heat transfers to the work surface first before dispersing.

Electrode-Positive

As you might have gathered, the term “electrode-positive” refers to the electrode being powered by the positive terminal and the direction of electric flow going from the negative terminal, into the work piece, and then flowing into the electrode last before entering the power source once more. “With few exceptions, electrode-positive (reversed polarity) results in deeper penetration,” says Lincoln Electric.

Current Flow

You’ll notice that when we spoke of the electrode polarity, we mentioned direct current. Often referred to as “DC,” direct current flows between the electrode and the ground and has a constant polarity. Alternating current, or “AC,” on the other hand, alternates polarity/current flow on a consistent basis, that is, “120 times per second with 60-hertz current.” Though you can use both electrode-positive and electrode-negative types of electrodes when working with either current, the “choice of current and polarity depends on the process, the type of electrode, the arc atmosphere, and the metal being welded.” If you think that’s complicated, just wait until you have to choose the correct material of filler rod or wire for your application. Remember, we said welding seemed like an easy process, but it’s much more than creating small lightning bolts to melt metal.

To put a lot of this into context, let’s consider the most common types of welding. Each type has its own unique way of welding materials together for a stronger bond. Knowing these differences will help you choose the type of welding you need for your project and by extension help you to weld with more success.

Use of the Arc: Common Types of Welding

We can’t go into too much detail here but let’s consider each of the common types of welding you’ll come across in your experiences. By the end of the article, it’s safe to say you’ll have a basic understanding of what welding entails. We hope you continue your education by attempting to do some welding yourself!

But first, let’s build the rest of the foundation for all the projects to come.

Flux Core Welding

Unlike many other types of welding, flux core doesn’t require the use of a shielding gas. Rather, use of a consumable wire electrode provides all that’s necessary for a clean weld. This wire electrode has a flux core (hence the name), which is what melts together the metal in your work piece.

Stick Welding

Flux plays an important part in stick welding as well. Flux coats the consumable welding rod, which allows for a cleaner welding environment. This also means you don’t have to use a shielding gas when welding stick.

MIG Welding

The wire you weld with in MIG welding is also consumable. However, you do need a shielding gas in order to create the best possible environment for a strong weld. Depending on what type of metal you’re welding and the thickness of that metal, (among other factors), you’ll need to adjust the feed rate of your wire, as well as many other settings.

TIG Welding

Last, but not least, TIG welding requires gas but doesn’t necessarily require a filler material to conduct the electricity from the welder to the work piece. Filler rod adds material burned up during the process of TIG welding; however, it’s not necessary for the process of welding to occur.

Now that you know what the common types of welding are, let’s take that knowledge and apply it to how an arc is created. We’ll refer to each different type of welding throughout the explanation so reference the sections above as you read through the rest of the article if you need to. Otherwise, let’s get started!

How a Welding Arc is Produced

If you’re a visual learner, pause your reading of this article and click on the link that follows, for The Welding Institute. Scroll down the page under the “How Does it Work?” header and you’ll find a simplistic drawing of the basic components of a welder—which all play an essential role in creating the welding arc.

Each of these components—the welding machine, the electrode holder, the electrode itself, the work cable, and the electrode cable—all work together to make the arc happen. Keep this picture in mind as we discuss the process of creating an arc and reference whenever you need to.

Power Source: the Welder

The impetus for the welding arc begins with the welder. After all, the main power source creates the electricity needed to both melt the work metal(s) and the electrode. Welding machines can be configured to produce AC or DC current, or both, depending on the model. It is this very current that brings the power—and heat—of the welder to the work piece.

Carrier of the Current: the Electrode Cable and Electrode

The electric current produced by the welder travels via the electrode cable and directs itself to the work piece via the electrode. As we mentioned above, the definition of the electrode differs from one welding type to the next. However, the main focus of the electrode is to exchange the power of the welder for heat and provide enough temperature to get the work piece to melt. Most often you’ll have an electrode holder that will provide a buffer between the welder and the current passing through the electrode.

Grounding Out: the Work Cable

Technically, the arc is next in the process between the welder and the work piece. However, in order to understand why the arc can move between the welder and the work piece via the electrode, knowing the purpose of the work cable is key.

We mentioned lightning in the very beginning of this article and now we’ll return to this natural phenomenon. Lightning occurs when charged particles in the sky connect to oppositely-charged particles on the ground. When they connect—and lightning strikes—the power created by the contrasting charges “grounds out.” This means that the charge becomes neutral and the power releases.

Think of the electrode cable as the charged particles up in the clouds. The work cable represents the oppositely-charged particles on the ground. A constant contrasting charge must move between the welder and the work piece. That’s what creates the lightning, or the arc. Even as the power “grounds out” into the work piece, more should be brewing inside the welder, ready to discharge into the work piece when called upon.

Raw Power in the Form of Light: the Arc

Okay, so calling it “raw power” might be a bit dramatic. But considering the amount of electricity moving through the arc—hence the blinding light that requires a dark shield—there’s a lot more energy at the end of your welding electrode than you might first think.

The arc basically contains the energy that moves between the welder and the work piece that grounds it out. It is the physical manifestation of the charged particles in the welder meeting the exact opposite- charged particles in the work piece. It’s a linear process that happens second-by-second when you’re welding and it’s what allows you to fuse metals together without having super powers.

To summarize: the welder creates a large charge of particles, which seeks out the oppositely-charged particles in the work piece. These two groups of particles meet and discharge their energy via the arc. The arc then disperses into the work piece. In order to sustain the arc, the welder and the work piece create a circuit via a ground or work cable. As long as the welder produces a charge, the arc is sustained.

Common Problems Associated with the Welding Arc (and How to Fix Them)

If you are having trouble creating an arc between your welder and your work piece, here are a few troubleshooting steps you can take. Sometimes welding simply takes a bit of trial and error but we hope the tips and suggestions below remove the frustration from the equation and allow welding to be the fun and rewarding pastime most find it to be.

• Arc not striking. The arc not striking can be due to many things, most of them easily checked off the list with a quick run-through of your equipment. First, check your power supply. Make sure you’re still plugged in and the connection is secure. You can also check that the ground is established and any other cables are firmly connected.
• Arc striking, but infrequently. Can’t get the arc to stay around long enough to melt any metal? Check your voltage and electrode. The voltage may be too low or your electrode might not be configured correctly.
• Arc doesn’t completely penetrate workpiece. This is a common problem that most people encounter when they first begin to weld. Generally speaking, incomplete penetration requires changing one or more factors in your welding setup. For instance, you might need a slower traveling speed. There are a variety of factors that could affect the depth of penetration. Use your welder as a guide or search online for guidelines if necessary.

These are just a few examples of the problems you could encounter while welding. Just remember that the arc is largely responsible for creating a successful weld. The more you can do to promote the arc, the better.

Coming Full Circle: Producing the Welding Arc on Your Own

We hope you’ve learned a lot about how a welding arc is produced. There’s quite a lot of technical knowledge to soak up. Understanding the process of welding is one of the best ways to graduate from a novice welder to an apprentice. Because whether or not you’re learning from a master, the key to welding lies in perseverance.

The best welding techniques take time and patience, so keep checking back for more helpful hints, tricks, tips, suggestions, and all-around interesting knowledge. Until then, happy welding!