Last Updated on January 8, 2022 by Luis Ferency
People with fancy welding degrees may find it challenging to understand the difference between AC vs DC Welding. Because the AC/DC debate may be deceiving at times, it’s crucial to compare the two in person.
AC and DC welding are two types of metal welding that create an arc using separate current flow. An arc is created among a terminal and the metals being fused in various methods of welding. The calefaction from the arc is utilised to weld the metals together. An electricity supply, which can be either alternating or direct current, creates the arc. The electricity supply used has an impact on the weld formed.
The electrode you select has an effect on the efficacy and cleanliness of your welding. Two forms of the flow of current are referred to as negative and positive, respectively. They’re referred to as either “straight” or “opposite.” The DC polarity does not change. Despite this, the AC polarity alternates between flowing in one way for half and the opposite way for the other half.
This was an introduction of these two categories, now let’s discuss these briefly:
AC vs DC Welding
We can make a more accurate comparison if we look at these two forms of welding, AC and DC welding, one by one:
Before we go into depth, let’s start simply by the actual definition of welding:
Welding is defined as joining together metal components by melting the surfaces using a blowpipe, arc, or other methods, pressing, hammering, or other means.
Forms Of Welding
There are two forms of welding that depend on the type of current we provide:
- AC Welding
- DC Welding
1. AC Welding
AC is a type of electric current that alternates direction many times each second. The polarity of a 60 frequency current changes 120 times each second. Because the magnetism and electric current rapidly switch direction, there will be no arc deflection with alternating current welding.
Typical AC is what you’d expect to see coming out of your home’s electrical outlets, and it’s commonly utilized in higher voltage equipment like domestic appliances.
Or in other words: Alternating current (AC) is electricity that alternates between flowing in one direction and flowing in the opposite direction, causing the voltage to reverse as well occasionally.
AC Welding Applications
Two or more magnetic metals can be welded together using AC welding.
This is impossible to do using DC welding. The following types of welds are appropriate for AC welding:
- Downhand heavy plate
- Fill up quickly
- AC is used for aluminum TIG welding at a high frequency.
The primary benefit of AC welding is that it allows beginner welders to work with magnetic materials.
The current in AC reverses direction and is unaffected by magnetism. The arc remains steady and is more manageable.
The use of AC welding is also recommended for the following applications:
- TIG welding aluminum is possible because the current allows for greater temperatures.
- Making repairs on machinery since the machinery typically has a magnetic field and is older, with rusty parts where the increased heat penetration with DC welding is a problem.
- Seam welding is utilized in shipbuilding because the current values are frequently more significant than those used in DC welding, allowing deeper plate metal penetration.
The quality of the weld is one of the two most significant disadvantages of AC welding. Because of the constant shift in directional flow, it is not as smooth as DC welding, and there is more spatter.
2. DC Welding
Direct Current (DC) is electricity that flows in a single direction and has a constant polarity voltage, either positive or negative. Batteries are standard in DC units, used in low-voltage devices like mobile phones and remote controls.
Electrode negative (DC) or direct current offers higher deposition rates in welding because the electrode melts off faster. Deeper penetration is achieved when the electrodes are positive (DC).
DC Welding Applications:
The best applications for DC welding are:
- Welding using a stick (SMAW)
- Welding can be done from above or from below.
- TIG welding on stainless steel
- Brazing using a single carbon element.
- Due to the continuous linear direction of the current, it provides a smoother weld with more minor spatter.
- It keeps an arc that is steady and stable, making it easier to manage and more trustworthy than AC current.
- It can weld thinner metals more effectively than AC.
The following are the main disadvantages of employing DC welding:
- There’s a higher chance of arc blow.
- It’s not suitable for welding aluminum because it lacks the high-intensity heat required.
- Electrical grids do not provide DC; it necessitates installing an internal converter to convert AC to C. As a result, the cost of using this approach is higher.
A weld failure can occur for a variety of causes in welding. Magnetic arc blow is one of the most aggravating.
This happens when a magnetic field is present in the area where the weld to unite two metal components is being prepared.
Magnetic disturbance can impair the quality of the weld owing to the interaction of the welding current’s magnetic field with the residual magnetic field in the metal.
The welding arc deflects away from the weld path and behaves irregularly as a result of the disturbance.
The welding operator must combat arc blow by attempting to maintain a constant electrical current, and the quality of the job typically suffers as a result. Only in DC welding does an arc blast occur. Switching from DC to AC is an excellent way to solve the problem.
AC vs. DC Welding: What’s the Difference?
The following are the significant differences between AC and DC welding:
- AC Welding Equipment is smaller than DC Welding Equipment.
- Most AC welding equipment is lighter than DC welding machines.
- AC welding machinery is generally simple to operate, but DC welding is more complicated.
- The cost of AC welding equipment is typically low, but the price of a DC welding machine might be high.
- AC welding machinery has a smaller voltage drop, it may be used from a greater distance, but DC welding machinery has a larger voltage drop and should be utilized from a closer distance.
We hope that we have covered almost every aspect of these two types of welding and that you will be able to distinguish between them, i.e., AC VS. DC welding. At last, when welding with any metallic electrode, the correct current and polarity must be used to ensure proper penetration, consistent beading, and satisfactory welding results.
Luis Ferency with experience of 35+ years is a semi-retired welder. Though his passion for welding and learning keeps him going further. He loves sharing his knowledge on his expertise in SMAW, GMAW, GTAW, and FTAW. Hence, this helped the new welders to seek leverage knowledge and improve their welding skills.