Those who’ve barely gone beyond the threshold of their welding journey might have trouble figuring out the differences between AC and DC welding. The AC vs DC welding debacle can sometimes be so deceptive that you’re better off comparing the two in the flesh.
So, how is alternating current (AC) welding different from direct current (DC) welding and vice versa? The answer lies mainly in these currents’ polarities. While AC welding shifts rapidly between direct-current positive and negative, DC is based purely on direct-current straight polarity. The material then determines how each method is applied.
What Is Alternating Current Welding?
AC welding describes the shifting electric current used in this particular process. While DC uses a straight-polarity current, AC utilizes one that shifts from one polarity to another and vice versa.
In a graph, this would be illustrated as a wavy line representing a fluctuating current instead of a straight line depicting a steady current. The AC is what’s typically used in today’s home wiring systems, so it doesn’t require modification once passed on.
Alternating Current Advantages
What edge does an AC system have over a DC system?
- Variety of Industrial Applications
Going for the AC option, you won’t miss people telling you about its drawbacks, particularly that it leads to messy welds. That said, it also holds a ton of advantages, most notably its practical repair applications for various industrial settings.
- Works Effortlessly with a Magnetic Field
Working with metals with magnetic fields typically calls on the AC welding process. That’s because AC is resistant to arc wandering. This refers to the tendency of the welding arc to misalign with the electrode due to the pattern of magnetic currents in the weld metal. It is often challenging to execute clean, straight welds when this occurs.
Immunity to arc wandering comes in handy when working with large machinery, which often contains different types of magnetic fields. Some examples of this heavy welding work include logging machinery, construction equipment, and even smaller machines such as tow trucks and forklifts.
Alternating Current Disadvantages
There are also some instances when the AC system doesn’t necessarily provide the best solution. That’s due to its:
- Inappropriate Polarity for Most Welding Needs
AC welding does not often suit most welding applications. If you want the best welding results, the straight-line current is usually where you will get it.
- Proneness to Arc Loss
Fluctuating currents sometimes result in the arc restarting itself at every turn of the positive and negative currents. Often, it fails to restart automatically and needs manual restarting. In addition, susceptibility to arc loss can break welds, making them flimsy.
- Spatter
AC welds are often messy due to the fluctuating current. Thus, you will find bits of metal all over your workstation when using this process. Welding processes are very rarely without spatter, but AC really takes it to a whole new level.
What Is Direct Current Welding?
On the other side of the spectrum lies direct welding. It uses a straight-line current to inject electricity to an electrode that connects two welded metals.
While the AC would appear as a wavy line in a graph, the DC would look like a no-fuss straight line. This directness of current flow is what keeps the arc from stopping during every polarity shift.
Direct Current Advantages
The DC system is not without its flaws. However, these drawbacks are greatly overwhelmed by the positives of utilizing this welding process.
- Beautiful Welds
Welds are usually the last thing one would describe as “beautiful.” Yet, in the case of a DC weld, the word would not be far off the mark when describing the outcome. The straight-line current in this method contributes to smooth, clean, and overall aesthetically pleasing results.
- Strong Welds
Aside from being superior in terms of aesthetics, DC also provides stronger, more durable welds. It goes without saying that strength is one of our main goals when welding things together.
Direct Current Disadvantages
While it has the edge in terms of overall welding outcome, DC does have some qualities that could disappoint you. These are:
- Difficulty of Application
Despite being suited for many simple, everyday welds, a DC system does not make engaging in these activities easy. In fact, some might think they would be better off using the AC process in some everyday welding scenarios.
- High Cost
Since electrical grids are not supplied with DC currents, you need an internal transformer to convert AC to DC. Transformers contribute to DC welding’s weight and complexity, which, in turn, make the process more expensive.
So, Will It Be AC or DC?
The answer mostly comes down to your purpose. In general, AC would be the best bet for most industrial welding applications if you don’t mind having messy finishes. On the other hand, despite its potentially hassling application, DC welding produces ideal results for everyday welding scenarios.
