Ac Vs Dc Welding: What These Two Terms Have Concerning Welding?

ac vs dc welding

AC and DC welding are two types of arc welding that can weld different metals and alloys. Depending on the nature of the electric current, each welding mechanism delivers mixed benefits and can be used for different applications.

So what is the difference between AC vs. DC welding? Which one should be your go-to option? In this article, we’ll analyze the pros and cons of each technique. So, keep on reading to learn more about these welding methods.

AC Vs DC Welding: What You Need to Know

AC and DC welding are two types of welding using different electric currents to produce an arc. The electric arc is created between the electrode and the metal surface you’re welding to fuse both metal surfaces together.

A power source generates the electric current, alternate current (AC), or direct current (DC). Choosing between these two affects the strength and quality of the weld. It also changes the polarity direction, which flows in one direction in DC welding and alternates between two directions in AC welding.

What is the Definition of AC Welding?

The AC electric power creates a current that reverses its direction many times. For example, a 60-Hz current will change its polarity and magnetic field 60 times per second. As a result, there will be no net deflection of the arc.

Represented on a graph, AC welding will have a wavy line or a fluctuating current. It’s not usually the preferred welding method, except in very few situations.

What is the Definition of DC Welding?

The electric power creates a current that has a constant polarity flow in one direction. It can be negative or positive, and it won’t change throughout the welding process. The magnetic field doesn’t change, so the arc produced is stable.

DC welding is represented by a straight line with steady output on a graph. In the case of negative polarity, the current flows from the welder to the electrode, then to the metal surface. The negative polarity is usually more popular for welding applications because it produces a hotter arc and faster electrode melting. It’s also called straight polarity.

If you’re welding thicker metals, positive polarity will be the right type of welding to choose because it produces deeper penetration. However, the welding process will be slower.

Pros of AC Welding

Using an alternating current while welding comes with a lot of benefits.

The arc is steadier when working with magnetic materials. The welding arc doesn’t get out of alignment, allowing you to finish the process with better results. This is known as arc blow and can be fixed using an AC welder.

An AC welder will be a better choice in projects requiring fast filling. Using a fast-filling electrode, you can achieve a high deposition rate to have the work done.

It’s the best welding type for shipbuilding to create good-quality seam welds.

AC welding can weld challenging metals like Aluminum, despite being a non-magnetic metal. Aluminum is covered with a layer of aluminum oxide, which affects the function of a straight weld. The alternating current creates a scrubbing action that removes this layer.

Welding equipment used for AC welding is cheaper than DC welding equipment. As a result, it’s an excellent choice for small-scale home improvement projects and DIY tasks.

Cons of AC Welding

Despite its pros, AC welding isn’t the most popular type of welding as it comes with several disadvantages.

Because the arc needs to resume itself every time it turns, it often happens that the welder has to manually restart the arc.

Dealing with spatter is another problem that welders usually face while using AC welding. This means you will spend more time cleaning off the metal surface. As a result, using an AC welding machine will make you finish the job over a longer period.

Excluding Aluminum, you can’t weld non-ferrous metals with an AC welder.

Thus, the weld created using an AC welder is not as clean and is more difficult to manipulate, especially if you’re a beginner or a less experienced user.

Pros of DC Welding

Several circumstances require the use of DC welding. It provides a smoother welding output than AC welding. As a result, most beginner and professional welders prefer to work with DC welding equipment.

Unlike AC welding, DC welding doesn’t create much spatter. It’s more convenient for most welders to work with because you don’t have to spend time cleaning off the surface once the welding job is done.

Due to the lack of spatter and sparks, DC welding is used in overhead and vertical applications.

DC welding machines can be used to weld ferrous and non-ferrous metals successfully.

Thanks to the clean and smooth arcs, DC welding is suitable for applications where the welds are visible. This is why it’s widely used in DIY projects, furniture, vehicles, and other metal applications where the appearance of the welded metal surface matters.

The created welds are stronger and more resistant to pressure.

The overall process is safer because it’s performed using low-voltage.

The welding arc produced is more stable, and there’s a smaller chance for mistakes.

DC positive polarity can weld thicker metals with clean and flawless results. DC negative polarity creates fast deposits that can come in handy when welding thin metal sheets.

DC welding can be used for TIG or tungsten inert gas welding, producing high-quality clean welds. It welds more metals and alloys than any other welding process and creates no spatter, fumes, or smoke. As a result, this method can weld thin metal surfaces in repair projects or artwork.

Cons of DC Welding

Although DC welding machines generally produce better welds, this welding method comes with a few drawbacks.

DC welding can’t fix arc blow problems as its arc produced is affected by the magnetic field created.

DC welding machines require the presence of an internal transformer to switch the current. As a result, the devices are usually more expensive than those used for AC welding. In addition, you need access to a 220V outlet.

Due to the presence of the transformer, DC welding machines are heavier and usually difficult to move around.

DC welding can’t be used to weld aluminum.

AC and DC Welding Machines

AC and DC welding machines use electric currents to create an arc that weld metals in construction and repair. The device features an electrode that allows the current to flow to the metal and heats it up. A filler rod then adds a little extra metal to fill the joint properly.

However, there are some differences between AC and DC welding machines.

AC Welding Machines

AC welding machines are restricted to one type of welding; arc welding. These machines are usually smaller and more compact, so they’re suitable for home garages and workshops with no big space to set up a large device.

These welders are also more affordable because they’re more straightforward to use. Because they’re small, these machines are more portable and suitable for jobs away from the job site. These machines are more accessible for repair purposes because they can be easily moved around.

AC welding machines are easier to operate and control. As a result, they’re more suitable for DIY enthusiasts and beginners.

DC Welding Machines

DC welding machines are suitable for industrial-grade projects and serious tasks. They are more durable, heavier, and larger than AC welders. They’re also more challenging to move, but they’re sturdier. However, it’s unlikely that a DIYer would buy a DC welder, as these devices are mainly designed for industrial and more advanced tasks.

Since these machines are designed to handle serious welding jobs, they’re more expensive than AC welders. Most beginners opt for AC welders because they’re more affordable and easier to use. However, professional welders with heavy welding workloads would benefit from investing in a reliable DC welder that can do most welding jobs.

AC/DC Welding Machines

These are the most versatile options as these machines can do AC and DC welding using alternating and direct currents. These flexible machines can combine various welding processes in a single unit, representing a good purchase for professional users. However, this extra flexibility costs more, so they’re not suitable for beginner users.

AC/DC welders represent a good choice for someone starting their welding workshop because they provide the best of both worlds. When money isn’t an issue, these machines represent a reliable and worthy investment.

Which Type of Welding Machine Do You Need?

Suppose you’re in the market shopping for a welding machine. In that case, you’re probably thinking about whether you should give an AC welding machine or a DC welding machine a try. Here are a few features to take into consideration.

Level of Experience

A beginner will always prefer dealing with an AC welder in most cases because they are easier to work with and safely used for small-scale projects. They’re also easier to store and move around. More professional users feel more confident when they use DC welders. DC welding machines can also be used for more applications.

Welding Position

The excessive spatter from AC welders creates a big problem when welding overhead or vertical. The spatter gets on the work area and takes more time to clean up. It can also get on you while you’re working.

In this position, using a DC welder will be a smarter decision. It’s safer and creates a cleaner finish. Your metal surface will be ready without spending a lot of time on cleanup.

Metal Thickness

DC welders are more suitable for thinner metal sheets. AC welders move too slowly, so they can burn thin metal. Speed is necessary when the thickness of the metal surface decreases. In this case, using a DC welder will be a better decision.

Job Nature

For most small home applications, DIY projects, and repairs, AC welders will work fine. These machines work on household current, and you don’t have to hire an electrician to set up new wires. Moreover, these welders are small, compact, and portable, so they can be easily moved around and stored when the job is finished.

For industrial-scale jobs, DC welders are more appropriate. These machines are more expensive and more suitable for detailed jobs that require a high level of professionalism. They’re also larger and more challenging to use and move around to be used in professional settings.

Magnetic Field

When working with steel pipes with a high percentage of nickel, it’s best to use AC welders. AC welders don’t experience arc wandering, which results in inconsistent welding lines due to the magnetic field created. DC welding machines experience arc wandering when working near a magnetic field.

Video: AC vs. DC Welding


Both AC and DC welding machines can be used for numerous applications. Still, they can’t be used interchangeably in most cases. Although both work according to the same basic mechanism, AC and DC welders have different traits and applications.

Most beginners prefer using AC welding machines because they’re easier to work with. However, professional users would either invest in a DC welding machine or an AC/DC welder that benefits both welding techniques.

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