What are AC/DC TIG Welders, and What Makes Them So Great?

Even if you’re relatively new to welding, you probably already know that AC and DC welding are types of arc welding using currents to produce an electric arc between an electrode and the metal to be fused. The process involves using a power supply to generate the arc, using either an alternating current (AC) or a direct current (DC).

Choosing a power source (AC or DC) determines the polarity of the electrical current running through the electrode and impacts the quality and strength of the weld.

Known as ‘straight’ or ‘reverse,’ the two types of current flow are sometimes referred to as ‘electrode negative’ and ‘electrode positive.’ The DC polarity is constant, while the AC polarity flows in one direction for half the time and half in the reverse direction.

Why would someone need an AC/DC TIG welder?

Many welders associate TIG with its use on thin metals only, but the reality is TIG welding has numerous applications for professionals and hobbyists. And AC/DC TIG welders are perfect for all those DIY projects such as automotive repairs and pipework.

An AC/DC welder is a versatile machine, giving extra flexibility to work with a broader range of metals and thicknesses with the option to work with alternating or direct current. The AC/DC TIG welder has features including variable current settings, up/down slope settings, a foot pedal, and several time controls, making it possible to expand the types of welds you can create and the types of metals you can work on.

What is AC TIG welding used for?

Welding aluminum is ideal for alternating current (AC) TIG welding since the alternating current has positive and negative cycles. The positive cycle has a scrubbing effect on the metal surface by removing oxides that adversely impact weld quality. In contrast, the negative cycle allows deeper weld penetration. The two cycles work together to produce high-quality aluminum welds.

Since this oxide layer encompasses aluminum, it is more challenging to weld. The oxide melts at a higher temperature (3200ºF) than the base metal (1200ºF) and needs to be broken up to produce a complete weld. Using AC enables a clear view of the weld pool.

Controlling the amount of heat applied to the weld is yet another potential problem since the conductivity strength of aluminum makes keeping enough heat in the weld pool difficult.

Much heat is required, but it needs to be controlled to prevent the weld pool from “running away” or a burn-through. Many experienced TIG welders use a shorter arc length to confine the heat to a smaller area or a foot pedal to allow them to adjust during the welding process.

What can you weld with an AC TIG welder?

AC welding allows aluminum and magnesium welding and is widely used for seam welding in shipbuilding, aluminum pipe TIG welding, automotive work, shipyards, and aerospace applications.

You can set the current higher with AC than with DC, and AC welding provides faster fills and is better for down-hand heavy plate welds. Another of the primary benefits of AC welding comes when working with magnetized materials, making it possible to use it in machinery repairs.

Do I need an AC/DC TIG welder?

Whether you need an AC/DC TIG welder depends on the type of welding you plan to pursue. If you occasionally see yourself welding steel or thick material, you don’t need more than DC. Considering that about 85% of all welding is completed on direct current, the odds are in your favor that you’ll be covered by it.

Some advantages of DC over AC TIG include a more stable arc, higher welding output, deeper penetration, and lower equipment costs. DC TIG welders are substantially cheaper than AC/DC machines, so that you can save money upfront.

However, even though DC covers most welding, it has drawbacks. The metal may be magnetized in some welding applications, and the arc blow issue appears. Switching to AC welding machines with special electrodes dedicated to AC can help you get around the problem.

Also, welding aluminum is impossible when using a DC-only TIG welder. Because of aluminum’s properties, dirt and high heat can wreak havoc when trying to weld it. Here, you’ll discover the AC welder’s main benefit when efficiently performing aluminum TIG welding without worrying about contamination or burning through the material.

What makes AC TIG so beneficial for welding aluminum?

Welding soft and non-ferrous metals require a reliable AC TIG process. As you know, the alternating current flow moves from positive to negative and back again many times each second. Whenever the flow reverses to the positive electrode portion of the AC cycle, meaning the current flows from the base metal back to the electrode, it provides a “cleaning” action as the electric arc blasts away surface oxides.

When the alternating current flows to the negative polarity, from the electrode to the base metal, it enables the metals to fuse correctly without worrying about burn-through or defects. As a result, AC TIG welding is ideal for joining metals such as aluminum, magnesium, and other non-ferrous metals.

Can you weld steel with an AC TIG welder?

Beginning welders have likely heard that everyone uses DC to weld steel and AC for aluminum, concluding that welding steel with AC is impossible. Although it might not be the ideal method, you can TIG weld steel if AC power is all that’s available,

So, even though you can use AC and DC for TIG welding steel, AC is not your better choice. If you’re buying a new machine for welding steel, get one that uses DC, which is more efficient for welding steel. And if you plan on welding steel and aluminum, spend the extra money for an AC/DC TIG welder and cover yourself for both types of material.

The TIG225X AC/DC TIG Welder has the versatility you need

PrimeWeld TIG225X AC/DC TIG Welder
PrimeWeld is the leader among welding companies and manufacturers for their lineup of affordable welding machines used at home or in the shop. For example, the TIG225X AC/DC TIG Welder with Pulse is one of their most versatile welders, ready to meet the challenge of your next project, whether it’s an aluminum sculpture, lightweight bicycle frame, or steel water tank.

The TIG225X has an AC Balance feature that lets you set the length of time to spend on each side of the AC cycle, as it removes oxidation from the part’s surface and impurities from the weld puddle. By varying the signal to a negative or positive time, you can change the degree of “stir” in the weld puddle.

On the other hand, DC TIG provides the low-temperature control for sheet metal or car bodies or the amps you need for thicker material up to 1/2-inch steel. And no welding process can equal the beauty of exposed TIG welds.
Add to those advantages a stick welding mode that saves money on shielding gas when the finesse of TIG welding isn’t required. Merely flip a switch, and you can do all types of repairs around your house or farm with DC stick welding up to 180 amps.

You name it, and the TIG225X will make short work of it. Like every PrimeWeld product, this machine stands under the harshest and most rugged real-world conditions. And the best part is the TIG225X AC/DC welder with Pulse gives you more for your money than other welders in its price range.

Backed by PrimeWeld’s outstanding support and hassle-free 3-year warranty, the TIG225X is the machine that was designed for your home shop or business. And our customer service makes it easy to connect with our team of real people, providing advice and sharing their know-how to troubleshoot every PrimeWeld model for optimum performance.

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