Choosing between AC and DC power supply during welding is often confusing, especially when you are new to the welding process. Alternating current and Direct current generally denotes polarity that should be utilized for a welding purpose. The polarity is utilized along with an electrode to create an electric arch, but both the source offer different performance. Choosing the right polarity is important because it determines the appropriate quality and strength of the weld. So let’s take a look at the account of AC vs DC welder.
First, we would like to start with AC Welding;
AC welding is an effective process where the flow of electrons keeps on moving back and forth so that voltage can change periodically. The electric charge move in certain direction half of the time and then the same electrical charge start flowing in the opposite for the second half. It holds prowess to modify its polarity 120 times per second with a 60Hz current, and this factor helps the welder in making deep welds or penetration. Even though it is often considered the second choice for welding, but it comes in handy in certain situations, especially when using a household power supply.
Many beginners and low-cost machines come with an AC power source, but you will hardly find them in higher ranges. AC welding is not suitable with all types of the electrode because the arc tends to go out, and it had to be welded again, so one needs to be careful while choosing. It needs specially coated electrodes that prevent the arc from going out and keeps it ignited. 6011, 6013, 7018, and 7024 serve as the common electrode choice for AC welding.
In terms of machines, AC machines are generally compact, so most of the models are quite light in weight. Like its size, they also consume a low amount of energy, and it generally resides between 3 and 4kWh. The voltage drop in AC welding is quite less, thus making it suitable for comprehensive coverage. The operation cost in this type of welding is comparatively less than DC so that anyone can opt for it. Similarly, the value of the machines is budget-friendly; thus it has a wide market coverage.
Let’s look at the pros and cons of AC welding along with the applications;
- AC Welding machines come at an affordable price.
- They are highly portable.
- It allows you to weld on magnetized materials.
- It works well on aluminum substances.
- The welding quality and cut is not as smooth as DC welding.
- It is quite challenging to handle the arc.
- It produces a lot of spatter.
AC welding may not be highly efficient, but it has numerous applications under its belt;
- It is mainly utilized for welding on magnetized materials.
- The aluminum TIG welding with high frequency is a popular application of AC welding. AC supports welding at a high temperature, so it becomes easy for welders during welding. Basically, aluminum comes with an oxide film on its top layer, and during the welding, when AC changes to the positive electrode, then it eliminates the oxide and makes the arc.
- Fast fill and down-hand heavy plate are some well-known applications of AC welding.
- In many industries, it is used for repairing machinery that is generally old and has a magnetized field. As they are old, so, they are mostly rusty, and only AC welding will be useful because it requires high heat infiltration.
- Shipbuilding sectors often use AC welding because it allows deep infiltration of plate metal, which you can’t get with DC welding. Inseam welding, during shipbuilding, the current settings are mostly higher than preferred in DC welding, so AC welding serves best for this purpose.
Now, let’s talk about DC welding;
DC welding is probably the favorite process when it comes to welding, and it is preferred by most of the welder because of the quality it offers. In the DC process, the electricity flows in a single direction and has a voltage with constant polarity. However, the polarity can be either positive or negative, depending upon the situation. It is widely used in many welding processes because it helps the welder to create a smooth cut, thus delivering better welding results. Not only it allows you to create a stable arc, but it also makes the process easier without oozing out much spatter. With that being said, DC welding works best with a 6010 electrode, and it has a high cellulose sodium coating that assists in deep penetration.
The polarity in DC welding is utilized in two ways where DC negative is used for swift deposition rate on thin sheet metal; thus, the electrode melts off quickly. It produces less heat, so it becomes easier to use on thin metal surfaces. On the other hand, DC positive comes useful for making deep penetration in the metal as the current flows to the electrode. The machines are larger, so generally, they have enormous weight. Most of the DC machines in the market come with a high price range, but the strength and quality they offer make it worth it.
You will mostly find DC welding in the large industrial sector as the operation cost they incur is pretty high. Moreover, they have a high power consumption of around 6 to 10kWh, so usually, it won’t be compatible with regular workshops. However, DC is generally found in batteries and low voltage devices for operating them. Unlike AC welding, DC can’t be utilized for a significant distance because it faces a high value of voltage drop. The major problem faced by welders with DC welding is that the arc is challenging to control even for seasoned welders. The magnetic disturbance gives rise to the arc blow, and it causes the welding to deflect from its weld path. So welder has to switch from DC to AC to avoid this issue.
So let’s check out the pros and cons of DC welding, and also its applications;
- The weld quality in DC welding is high and smooth.
- Due to the constant linear direction of the current, it creates low spatter.
- It is easier to handle and maintains a stable arc.
- It offers better results with thinner metals.
- Works really well for vertical welding.
- Machines associated with DC are easy to use.
- It faces a lot of arc blow.
- It is highly expensive.
- The welding gets affected by high-intensity heat.
- DC is not available from the electrical grid, so you need transformers to change it from AC to DC.
Now check out the applications associated with DC welding;
- The most common use of DC welding is stick welding processes.
- Stainless steel TIG welding is mostly carried out utilizing DC welding methods.
- Single carbon brazing is another popular application of this welding type.
- It is widely used when it comes to vertical or overhead welding because you can accomplish it with AC welding.
- Welding of thinner metals requires DC welding.
- It is often used for creating massive deposits.
- Cutting taps also need the polarity of DC.
Sean Coby is a welder par excellence and well respected among the welding community in Woodbridge, VA. He prides himself to be the fabricator and mechanic in the automotive/ diesel industry for the past more than eight years now. As the chief editor of his https://weldinginfocenter.com, he shares his experience to be safe during welding and to take proactive steps for becoming a successful welder like him.