AC vs DC welding – Main Differences and Applications


Why do welders prefer DC? What are the main differences between AC and DC welding? Which one should I use? – These are some common questions you might have if you are getting into the art of welding.

The difference between AC and DC current determines the nature of these two types of welding. Below is a thorough comparison of the two and a detailed conclusion on which one you should use under what circumstances:


Definition


Before heading into the definition of the two, let’s understand AC and DC power. AC stands for Alternating Current that changes direction or alternates between positive and negative. The regular electricity that we use in our household from power outlets is AC power.

On the other hand, DC or Direct Current, as the name implies, is linear and travels straight. Examples of DC power are batteries, fuel cells, solar panels, etc. You can also convert AC into DC. Now, let’s look at the definitions of AC and DC welding.

AC Welding

The welding procedure which uses AC as its electric power can be called AC welding. The current used for such welding alternates instead of having a direct path. Imagine a wavy line; that is a good representation of this type of electric current.

DC Welding

When direct current is used for welding, it is simply DC welding. A steady stream of electric power is received in the electrode, which helps welding materials. You can use DC welding in both positive and negative polarity.


Basics


The primary factor differentiating both types of welding is polarity. Electric circuits consist of negative and positive poles. Direct current has a constant polarity while AC power changes direction and is completely opposite of DC power.

This change of direction between positive and negative makes the AC welding inferior. DC is the preferred electric power for most welding tasks, and welding devices are usually used with direct current.


Advantages and Disadvantages


Even though DC seems to be superior for welding in most cases, specific works require AC power. Each has its own pros and cons.

DC Welding Pros

  • Since DC has a constant polarity, it can provide smoother welds. It causes the least amount of spatter. So, it is suitable if you need a better-looking weld for aesthetics.
  • DC welds are longer-lasting than AC. Various factors play into this, but primarily, it is the result of the steady polarity of the welding.
  • DC welding has a more stable arc.
  • DC offers two types of welding polarities (positive and negative), and it provides you more options to work with.
  • Negative DC is highly suitable for speedy deposition.
  • Positive DC has higher penetration.

DC Welding Cons

  • DC welding requires you to use a transformer that can turn AC into DC. As a result, DC welders are more expensive.
  • Requiring around 220V circuits, you need to take help from a professional electrician before starting to work.
  • Arc blow problems make DC harder to use.
  • More skill is required for welding with DC as it is complex.

AC Welding Pros

  • Metals with magnetic fields are easy to weld with AC, and it solves the problem that DC has with arc blow.
  • AC can be used in limited power options, and most home welders prefer it.
  • When TIG aluminum welding, AC seems to be a superior option.

AC Welding Cons

  • Sometimes arc is unable to restart because of alternating current. A manual restart is often required with this welding.
  • AC welds don’t have a clean finish, unlike DC.
  • More complicated for beginners.

Applications

Most of the stick welding tasks require you to use direct current. Moreover, if you are working with thin materials, DC is the preferred option. Vehicles, furniture, and anything where aesthetics are involved, DC can provide a clean weld!

Professionals who are looking for precise welds and good finish use DC even though it is the more expensive option. Its superiority makes it highly applicable in most weld tasks.

For welding aluminum, AC is the better option as it can take out oxide from metallic surfaces. That’s why AC welders are used for TIG aluminum welding.

AC welds are also faster and used in making ships and heavy plates. Moreover, professionals prefer alternating current for repair tasks and welds that do not require much aesthetic value. Hobbyist welders prefer AC because it is cheaper and can provide a faster filling.


Final Note


AC and DC power have their specific usage in welding. It is better to get a quality welder that can be suitable for both types of welding. Even though they are a little more expensive, they are surely worth it, as most professionals would agree.

So, depending on what kind of welding tasks you will be doing, you can choose the right welder according to AC or DC power.

Last Updated on 1 month by Richard Boyer

  • June 19, 2021
Richard Boyer
 

Richard Boyer has been a professional welder for over 27 years of his life, and now he is a trainer and blogger providing critical information to anyone interested in welding. He is helping out both hobbyists, novice and professional welders to learn newer and better techniques. Read more about me

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