AC versus DC welding What's the Difference

AC versus DC welding | What’s the Difference?

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AC versus DC welding, which is the more stable option and which one should you select?

Since you’ve found this article, that is the question you have been wondering about!

Welding can be very complex for the beginner who is just attempting to get started, and there are many different options and questions that can seem quite overwhelming if things are not broken down for you.

We actually got asked this question from a reader: “what is the difference between AC versus DC welding?”

I (Harry) can often answer these kinds of questions without Brian, but I had to get a detailed opinion from him because it is more nuanced than a simple this and that answer!

The simple, shorter explanation to this question is:

  • AC welding is a simpler welding system. It is mainly used for carbon arc welding and brazing.
  • DC powered welding is used with many more applications and has a lot higher power output.

Keep reading to learn more and get a more in-depth explanation of what the differences are between DC and AC welding.

An in-depth Comparison of the Difference Between a DC and AC Welding Machine

In order to join certain materials together, welding is necessary.

In order for a weld to be created between metals, there is an electrical current that is used for heating the metal up hot enough so that it melts together.

The result is that this creates a strong bond.

Like with any other electrical current, this involves two poles, a negative one and a positive one. The polarity creates the difference between these two types of currents.

To completely understand the difference between DC versus AC welding, you must first understand the concept of polarity (it isn’t necessary to flashback to your high school physic class, but you must have at least a basic knowledge in order to understand it).

What is Welding Arc Polarity and Why is it so Important?

Welding Arc Polarity Explained:

Polarity significantly affects how strong a weld is.

In the meantime, electrode-positive, which is also referred to as reverse polarity, first causes a penetration and then it causes an electrode-negative polarity (reserve). Therefore, usually, there are are two forms of polarity:

  • Welding straight polarity
  • Welding reverse polarity

In Arc welding, reverse and straight polarity is a common term.

DC is usually the preferred form of welding polarity. So what is the difference between a DC versus an AC welding machine?

DC Welding Overview

This is a solid option for beginners who are just starting to learn how to weld.

DC stands for Direct Current. With this process, a charge travels in just one direction and returns a constant polarity. As previously mentioned, welding has mainly two types of electrode connection They are:

  • Current electrode negative (direct)
  • Current electrode positive (direct)

Therefore, Electrode straight or negative (DCEN), is a faster process, and the electrode melt-off is fairly fast.

Less heat is produced by a straight current compared to a positive electrode. This is why it is widely used on thinner substrates.

What Working Principle is used by DC Welding?

The electrode is positive with the DC reverse polarity method. However, the current flows to the electrode from its workpiece.

DC Welding Advantages

  • Great to use with thinner materials
  • Leaves a smoother arc
  • Better when used with vertical welding
  • Fewer outages and less sticking
  • Easy to start
  • Less splatter

DC Welding Disadvantages

  • Doesn’t work well with high-intensity heat
  • More expensive
  • Cannot be used with fix arc blow

AC Welding Overview

AC stands for Alternating Current. The electric charge moves in a certain direction 50% of the time and then in the opposite direction for the other half of the flow.

In plain English, the electrons flow continues to switch directions and goes back and forth. Therefore, it is able to change its polarity up to 120 times per second.

In welding, AC should be the second option. There are, of course, a few cases where AC welding is the preferred option. For example, there are some low cost, entry-level machines that just run AC power.

The following are some of an AC welding machine’s advantages and disadvantages.

AC Welding Advantages

  • Highly portable
  • Works well on aluminum
  • Affordable
  • Magnetized materials

AC Welding Disadvantages

  • The cut is not as smooth as DC
  • Creates more spatter

Distinct Contrasts Between DC versus AC Welding

There are some major differences between the two that can have a major impact on whether AC versus DC welding is the best option for you.

First, let’s discuss size.

AC are small machines. This results in the weight being fairly light.

DC, on the other hand, is fairly heavy and larger.

Now We Will Discuss the Voltage Drop.

With AC welding machines, there is less of a voltage drop. Therefore, it is possible to use it for long distances.

By contrast, the DC voltage drop is higher and may be used at only short distances.

AC machines are fairly affordable, while DC machines have higher operating costs. With AC welding, less electric energy is also consumed per kg of the metal that is deposited.

The applications and uses make a big difference between these two types of welding. Only a couple of machines may be used with an AC power supply that needs to have low power factors.

Types of Welding that use AC

  • Downhand on heavy plates
  • In shipbuilding
  • TIG welding aluminum

Types of Welding that use DC

DC welding, on the other hand, can be used wherever the machine engine is driven by a DC generator, or with a rectified AC supply.

So it is more versatile and many machines are supported. Here are the kinds of welding that use DC:

  • Low hydrogen
  • Arc bronze rod
  • Heavy aluminum
  • Rivets
  • Sheet metal
  • Vertical
  • Overhead
  • Cast iron

Finally, and not the least, AC welding maintenance is easier and more economical compared to DC.

Frequently Asked Questions

What is the difference between AC welding and DC welding?

AC welding is a simpler welding system. It is mainly used for carbon arc welding and brazing. DC powered welding is used with many more applications and has a lot higher power output.

Are MIG welders AC or DC?

AC can be used for MIG welding and is often used on the cheaper machines.

Why is DC preferred over AC?

AC is often preferred over DC as it is easier to keep the voltage as well as change it if necessary. AC welders are often cheaper than their DC counterparts and are found in cheaper home welding options.

Is DC more dangerous than AC?

AC is more dangerous than DC as a result of triggering more severe muscle contractions. However both can be fatal if not given the proper respect or training.

Do you use AC or DC to weld aluminum?

Welding with AC current if preferential for welding aluminum.

So Which is the Best Option in the Battle Between AC versus DC welding?

As you can see, they both have specific areas where they are each unbeatable. Therefore, DC or AC welding is used to complete different tasks.

However, in most situations, a DC welding machine will be more advantageous when compared with AC welding. But there are certain cases where classic AC will be the best option.

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