What’s the Difference Between AC and DC Welding?

During welding, a supply of electricity is required for the machine to function and do its job.

Typically, the amount of voltage needed is significant, since welding work calls for a lot of power. Two types of electrical current can provide power to the machine: AC and DC.

What are AC and DC?

The polarity of the electric current created by the welding machine, which runs through the electrode, is called either AC or DC. There are two types of polarity, and the welding quality and efficiency depend significantly on the type of current used.

DC stands for Direct Current. When electricity flows in a constant direction, or if it maintains a constant positive or negative polarity, we refer to it as Direct Current. Usually, batteries of small devices like phones, flashlights or remote controls use DC.

For welding, DC, with electrode negative, causes the electrode to melt off faster. This helps create a quicker deposit yield, making work more efficient. DC with electrode positive provides an opportunity for deeper penetration.

AC, on the other hand, means Alternating Current. This provides a type of electricity that causes the current to keep changing directions, and with it, the voltage keeps reversing. The polarity of AC changes 120 times per second. As worrisome as this process may sound, reversed polarity provides deeper penetration.

Commonly, AC is used for high voltage devices. Electrical outlets will typically give out AC and are used for many large, powerful tools in the household or official work.

What Are the Differences?

Now that we know how each type of current works and what they are specifically used for, we can dive into the advantages and disadvantages of working with them. Welding can be done on different materials, in different ways, and the efficiency and results depend significantly on the type of current used.

To determine which type of power source to use, you must know what material you will be working on, what sort of welding is required, and most of all, the pros and cons of each current. So, let’s look at the many differences between AC and DC welding.

AC Welding

Pros

  • AC supports a few types of weld, like, down-hand heavy plate, fast fill, and aluminum TIG welding with high frequency.
  • One of the pros of AC welding is that it can be used for magnetized metal welding, which is not a function DC provides. Since the current in AC changes direction regularly, magnetized metal doesn’t affect the direction of the electrical arc.
  • This type of current allows welding in higher temperatures.
  • Since AC can provide a higher current level, it allows a comparatively deeper penetration in metal plates. So, it is often used for seam welding, which is required in building ships.
  • AC welding is great for repair work on machinery since most of them consist of magnetized fields and rusted areas.

Cons

  • The directional instability of the AC is also disadvantageous in welding. The main problem is, the product yield is less than what results from using DC.

DC Welding

Pros

  • Just like AC, DC is used for a few specific types of welding, namely vertical welding, single carbon brazing, stainless steel TIG welding, etc.
  • It is excellent for a user who requires a better build-up of massive deposits.
  • Unlike AC, this type of current produces a lower amount of spatter, resulting in a smooth weld and higher product yield.
  • The reliability of this type of current is higher than AC, making it much easier to work with. This is due to the constancy and stability it ensures in the electrical arc.
  • Thinner metals can be welded more easily with the use of DC, which is desirable to welders.
  • Best of all, machines that require DC to function are much cheaper, so they help out greatly in the cost-cutting process.

Cons

  • Even though the machinery is cheaper, the whole process of using DC is slightly more expensive. This is because special equipment, like internal transformers, are required to switch the AC to DC since the latter is not provided by any electrical grid.
  • While it is ideal for welding many different materials, it is not recommended for aluminum, which requires a high-intensity heat production, not provided by DC.
  • There is a big risk of arc blow if a magnetic field builds up.

Which Should You Choose?

The answer to this question still lies with the user. Ensuring a good weld, of course, relies on much more than just the type of electrical current being used. Since all the machinery is completely dependent on electricity, it still best to decide on which sort of current will be ideal for your job.

Given the advantages and disadvantages noted down in this article, it is best to remember that all factors must be considered before deciding on either AC or DC for your use.

And that means, considering the material you will work with, the type of weld you want, the amount of yield you can settle for, and much more.

Added to all that, you must ensure that the machinery you use is reliable and suited to the use of whichever source of energy you are rooting for.

You will, of course, want a minimal amount of spatter and the lowest risks of arc blow, so, make sure all your equipment and electrodes are in perfect order.

Conclusion

There is no one perfect type of current you can use. Whatever suits your purpose is the right one for you. If the material you are working with happens to be thin, magnetized metal, then the best bet would be AC. If you put stability over most other factors, go for DC.

Most of all, when you weld, you must have enough knowledge, so you do not make a mistake. So, weigh out your options, and the pros and cons, then choose the right type of current, that will ensure the best weld and fewer risks.

Here is the link to a YouTube video, if you want some visual details:

 

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