Arc Welding

Arc Welding
Electric arc: A strong and sustained gas discharge phenomenon, where there is a certain voltage between the positive and negative electrodes, and the gas medium between the two electrodes must be in an ionized state. When igniting a welding arc,
the two electrodes (one being the workpiece, the other being the filler metal wire or welding rod) are usually connected to a power source, briefly brought into contact, and then quickly separated. A short circuit occurs when the two electrodes touch, forming an electric arc. This method is called contact arc ignition. Once the arc is formed, as long as the power source maintains a certain potential difference between the two electrodes, the arc can be sustained.
Characteristics of the electric arc: Low voltage, high current, high temperature, high energy density, and good mobility. A voltage of 20-30V is generally sufficient to maintain stable arc combustion, while the current in the arc can range from tens of amperes to thousands of amperes to meet the welding requirements of different workpieces. The temperature of the arc can reach over 5000K, capable of melting various metals.
Composition of the electric arc: It consists of three parts: the cathode region, the anode region, and the arc column region.
Arc welding power source: The power source used for welding arcs is called an arc welding power source, which can usually be divided into four categories: AC arc welding power sources, DC arc welding power sources, pulsed arc welding power sources, and inverter arc welding power sources.
DC straight polarity: When using a DC welding machine, if the workpiece is connected to the anode and the welding rod to the cathode, it is called DC straight polarity. In this case, the workpiece receives more heat, which is suitable for welding thick and large workpieces;
DC reverse polarity: When the workpiece is connected to the cathode and the welding rod to the anode, it is called DC reverse polarity. In this case, the workpiece receives less heat, which is suitable for welding thin and small workpieces. When welding with an AC welding machine, there is no issue of straight or reverse polarity because the polarity of the two electrodes constantly alternates.