The Difference Between AC Welding And DC Welding?

With the advancement of technology, the development of welding has also made significant progress, especially with the popularization of medium-frequency resistance welding, which has greatly improved energy conservation and emission reduction. Unlike laser welding, resistance welding has two major forms: AC welding and DC welding. Today, let’s talk about the differences between AC welding and DC welding!

What is AC Welding?

AC welding refers to the resistance welding technology that uses AC as the power source. The principle is to weld metals by generating resistance heat through electrodes through AC. This is a more traditional form of resistance welding, suitable for low-cost, high-current, and thick plate welding scenarios.

What is DC Welding?

DC welding uses a MFDC power supply. The principle is to use unidirectional DC power and a continuous and stable output current, which can instantly generate a large amount of resistance heat to melt the workpiece and form a firm joint. DC welding is more suitable for high-precision and high-efficiency welding needs, such as welding of automotive parts.

The Difference Between AC Welding And DC Welding

In terms of electricity consumption

AC welding uses a single-phase 380V AC voltage. When a large welding current is used, it will cause a voltage drop in the power grid, unbalance the three-phase power grid, and pollute the power grid. DC welding uses a three-phase 380V AC voltage input. The voltage is first given to the inverter, the frequency is converted to 1000HZ, and then to the welding transformer. The three-phase power grid is balanced. After the frequency becomes higher, the primary welding current is reduced, saving energy.

Current Stability

During AC welding, the output current will fluctuate due to the fluctuation of the grid voltage. The DC inverter has capacitor energy storage, IGBT intelligent current output control, and touch screen visual display to ensure the stability of the welding current.

Current Influence

There is no rectification in the secondary output of AC welding. The length of the return current has a great influence on the output current. When welding some relatively long workpieces, the current has a great influence. The secondary of the DC welding transformer has a high-power rectifier diode for rectification, DC output, and the length of the welding circuit has little influence, which is suitable for welding longer workpieces.

Welding Accuracy

Since the AC is 50HZ, the AC welding time is in units of 1 cycle, and the welding accuracy is 20MS. It cannot be finely adjusted. Due to the increase in frequency, the accuracy of the welding time is more refined, and the minimum time can be in units of 1MS, which has higher accuracy and greatly improves the appearance of the welded product.

Limitations of Welding Materials

AC welding requires a long welding time due to the unstable output current, and there are few types of materials that can be welded. Some materials have low melting points and the workpiece is easily deformed. For example, AC welding is not suitable for welding aluminum materials. DC welding can be welded and formed instantly due to its DC output, and can spot weld aluminum plates, which is something that AC resistance welding machines cannot do.

Application Equipment

AC welding uses AC welding machines, and its biggest advantage is that the equipment cost is lower than that of AC and DC welding machines. DC welding machines are more suitable for the development of modern industry and are widely used in metal processing.

Through the above comparison between AC welding and DC welding, the advantages of AC welding are obvious! If you want to know more, please consult Agera technicians. We will provide you with a one-stop welding solution for resistance welding.