Are you confused about the differences between AC vs. DC welding? Or unsure about which to use? If so, you aren’t alone.
Welding is one of the oldest methods of joining metal and has been around for centuries.
It consists of using an electric arc or flame to melt a base metal to join two pieces. It is a great way to join metals together.
In this article, you’ll learn about the AC & DC welding differences with pros & cons and significant uses of both.
AC vs. DC Welding
DC stands for direct current, which means that it flows in one direction only. The electricity flows from the positive terminal (red) to the negative terminal (black). AC stands for alternating current, which means that the electricity alternates between positive and negative terminals at specific frequencies. This is known as frequency modulation (FM).
In DC welding, the voltage can be adjusted depending on what you are trying to accomplish with your weld.
For example, a lower voltage will give you a smaller puddle or bead, while higher voltages will result in larger puddles or beads.
AC power source has several advantages over direct current (DC). For example, it tends to produce more consistent puddle sizes than DC sources because it does not have any inherent polarity issues like DC sources do.
Therefore, its output voltage remains constant regardless of polarity changes within its electrical system, and this makes it easier to control
Major Differences
AC and DC welding are both used for a wide range of applications, from minor repairs to major structural work.
However, there are some major differences between them that you should know about before you make your selection. Following are some differences:
1. Welders:
AC welding is less expensive, portable, and lightweight. I suggest this one for hobbyists who want to do their own welding at home and professionals who work on smaller projects.
It’s also easier to learn than DC welding, which means that you can get started in AC welding sooner than you would in DC.
DC welding is more expensive and heavier than AC welding because of the need for an external power source, such as an electrical generator.
The equipment used for DC welding is typically much larger than that used for AC welding, so it’s not as portable, but it does provide more power for larger projects like structural steelwork or heavy machinery repair.
2. Polarity:
The major difference between AC (alternating current) and DC (direct current) welding is the polarity of the welding current.
In AC welding, the polarity of the welding current alternates from positive to negative at a set frequency.
This allows an arc to form between two electrodes when they are brought together and for a weld to be made as soon as it has cooled down enough for the metal to solidify.
In DC welding, there is only one polarity that can be either positive or negative. Because there is no alternation in polarity over time, it takes longer for an arc to form and for a weld to cool down enough for solidification to occur.
3. Strength of Weld:
When it comes to the strength of a weld, there’s no contest: DC welding is the clear winner.
AC welding is known for its spatter, which can be a real problem when you’re trying to create a smooth, seamless weld. It also tends to be weaker than DC welding, which means you’ll have to work harder to get the best results.
On the other hand, DC welding produces a strong and smooth weld without any of those pesky problems associated with AC welding and without having to work as hard!
4. Uses:
AC Welding is better for magnetized metals and aluminum. It works by passing a current through the metal, which causes it to heat up as it passes through.
The advantage of this type of welding is that it can easily penetrate even the thickest steel plate, making it ideal for overhead welding and vertical applications where you need to get close to your workpiece.
DC Welding uses a direct current instead of an alternating current. The advantage of this type of welding is that it produces fewer sparks than AC welding does.
This makes it better suited for thinner plates like stainless steel or aluminum because they’re less likely to be damaged by the sparks created by an AC current passing through them than a thicker piece would be.
5. Stable Arc:
When it comes to AC and DC welding, the most important difference is arc stability. If you’re a hobbyist or professional welder, you know how important it is to have an arc that’s stable enough to work with.
Not only does this mean that your welds will be cleaner, but it also means that you’ll be able to get them done faster.
When you’re working with an AC welding machine, you have a lot of control over the arc. This is great for when you’re trying to control how much heat goes into the weld, but it can also be difficult to work with because the arc is unstable.
DC welding, on the other hand, has a stable arc that’s easy to work with. The only downside is that it’s not as easy to adjust how much heat goes into the weld.
Pros and Cons of AC Vs. DC Welding
AC Welding Advantages & Disadvantages
| No. | AC Welding Advantages | AC Welding Disadvantages |
| 1. | The equipment used for AC welding is less expensive than that used for DC welding. | It is more expensive to use AC welding than DC welding. |
| 2. | It can be used to weld different metals together, such as aluminum and magnesium, with TIG welding. | The welds are not as strong as those made with DC current. |
| 3. | There are no issues with the arc starting or stopping, as it is controlled by the machine. | AC TIG welding equipment is expensive compared to DC TIG welding. |
| 4. | Better control over weld pool shape and penetration. | You need to keep the electrode in contact with the metal to make a good weld, which is difficult if you’re working on a large object. |
| 5. | Using AC on some stick welding electrodes, you will get better results. |
DC Welding Advantages & Disadvantages
| No. | DC Welding Advantages | DC Welding Disadvantages |
| 1. | DC welding offers excellent control over the arc length, allowing you to use fine wire feed rates and low travel speeds. | It is not possible to weld magnetized metal because of arc-blowing risk. |
| 2. | DC welding is a quick process. In comparison to the AC method, it takes less time to complete a weld. | It is difficult to weld aluminum through DC TIG & shielded metal arc welding. |
| 3. | Since there is less heat involved in a DC weld than in an AC weld, there are fewer problems with porosity and slag inclusion. | The equipment used for this type of welding is expensive and not easy to use for beginners. |
| 4. | When using a DC weld, you can adjust the current as needed to control the rate at which the metal melts and flows together during the process. | DC welding is not as easy as AC or arc welding because it requires more practice and skill than other types of welding. |
| 5. | During DC stick welding, you will have better penetration. |
AC & DC Welding with Different Welding Procedures
When it comes to welding, AC and DC are the two most popular methods. While both processes have their merits, each has its own limitations.
In this, I am going to share information with you about how AC/DC welding works with different types of welding procedures.
AC/DC Flux-cored Welding:
In order to weld flux-cored wire with an AC/DC machine, you need to set up your welder for DCEN (direct current electrode negative). This is the opposite polarity of what is required for gasless or self-shielded flux-cored wires.
If you are using a traditional MIG welder, you will need to reverse the polarity in order to weld this type of wire.
AC/DC MIG Welding:
MIG welding is a process that uses a wire electrode to weld. It uses DCEP polarity and is usually carried out with a machine. The MIG welding process uses DCEP polarity, the same as stick welding.
I do not recommend DCEN for MIG welding because there may be arc stability issues. In fact, you can’t even manually arc-weld with DCEN because it won’t work well at all if you do so.
For aluminum pulse & other industrial welding applications, it is recommended to use AC MIG welding.
AC/DC Stick Welding:
If you are looking for a welding procedure that offers good penetration while using the stick electrode, DC Electrode Positive (DCEP) is your best choice.
This procedure can provide even better penetration than DC Electrode Negative (DCEN), even if the electricity is focused on the stick welding electrode.
AC TIG:
In DCEN, there are no pauses in the current flow because it’s constantly on. The arc length depends on how fast you move the torch.
DCEN is more suitable for thicker metals because the arc does not last long enough to melt through them before jumping away from them again (as opposed to DCEP).
DCEP uses a constant current with pauses between pulses; this means that it heats up much faster than DCEN and cools down more quickly.
This welding procedure is better suited for thin metals because it allows them to be fully melted before jumping away again. However, if too much heat builds up, then it can cause burn marks on your workpiece!
DC TIG:
DC TIG, or direct current-tungsten inert gas welding, is one of the most common welding processes. It’s used for a wide variety of materials and applications.
When it comes to polarity, DCEN is the most common type used for this process. DCEP (direct current-electric pulsed) is less common but still used in some situations.
A DCEN welder uses an alternating current at a frequency of 50 Hz or 60 Hz. It uses a constant direct current voltage and a constant direct current amperage when conducting the weld.
A DCEP welder uses an alternating current at a frequency of 25 kHz or more with an alternating polarity (positive then negative). It uses a constant direct current voltage without any direct current amperage during the welding process.
For DC TIG, I recommend using DCEN polarity because of having a better current & heat on the welded material.
AC Welding Uses
AC welding uses are manifold. It can be used for a variety of tasks and applications, including:
- Welding aluminum and other metals
- Fusing plastic or other materials into metal
- Joining dissimilar materials together
- Magnetized/ Non-magnetized metal
DC Welding Uses
DC welding is a process that uses direct current to weld together two pieces of metal. The process has been around since the 1800s, and it has been used in many different ways since then. Here are some of the most common applications for DC welding:
- Weld different metals like stainless steel, steel, cast iron, copper, brass & bronze
- Non-magnetized metals
- MIG, Stick, flux core & DC TIG welding processes
Final Words!
If you want to get the right weld done in the right amount of time, it’s worth your while to consider AC vs. DC welding. Both methods have their own pros and cons, but the choice is ultimately up to you.
The choice between AC and DC welding depends on factors such as the material you are working with and, in some cases, the type of wire you will be using. It also depends on whether you are looking for a continuous or strike arc.
Make sure to choose the type that best serves your purposes because too much current can ultimately damage the overall product.
FAQs:
Is it better to weld with AC or DC?
The answer is that it depends. Generally, when welding mild steel, DC is better than AC. When you are using thicker metals, the arc exhibits more thermal stability and has better penetration capabilities with DC current.
Is DC welding easier than AC?
Yes, DC welding is easier than AC because the arc does not weaken with distance as an AC arc does. Therefore, DC Arc Welding can be done at greater distances from the workpiece. Because DC welding current is more stable, it requires less skill in arc control than AC.
Is DC welding safer than AC?
DC welding is safer than AC in many ways. There is less current involved, so the arc will not arc back to the gun. It also forces you to concentrate on what you are doing because there is no feeder being supplied by the machine, so if you stop feeding the wire into the electrode holder, it will quickly break off and leave your work unfinished.
Is TIG welding AC or DC?
TIG welding is usually done with AC power because it makes it easier to control the arc length. DC power can be used, but it is harder to use than AC. It should still give results that are acceptable for most people.
Can you weld steel with AC?
Yes, AC can be used to weld steel. Stainless steel and low-alloy steel can be effectively welded. The AC current is often much faster than DC (direct current), so you can get the job done faster.
