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 differences between AC and DC welding;
First, we would like to start with AC Welding;
AC welding is an effective process where the flow of electron 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 as the second choice for welding, but it comes 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 serves as the common electrode choice for AC welding.
In terms of machine, 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 during, 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;
Now, let’s talk about DC welding;
DC welding is probably the favorite process when it comes 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 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 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 it’s applications;
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.