How Does an ARC Welder Work?

What is arc welding?

Arc welding is an integral part of modern industry. As with all welding methods, arc welding heats two pieces of metal, causing the metals to melt into each other. When the heat is removed, the metal hardens and the two pieces of metal are fused. The difference between arc welding and other forms of welding is that the heat is generated by an electric current. The benefit of arc welding over other techniques for joining metals is that the fused section is often just as strong as the rest of the structure. As opposed to soldering or brazing, the joints are not potential weak points and are made of the same material as the objects being joined.

The arc itself consists of an electric current running between two electrodes--one positive and one negative. While the current is sustained through continuous electrical flow throughout the welding process, more is needed to jump-start the electrical circuit. A higher initial voltage is necessary to create a strong enough spark to ignite the arc. Another technique is to simply touch the electrode to the piece of metal being worked on, and then withdraw it slightly. The arc is extremely hot, reaching 6,500 degrees F at its tip. This is more than hot enough to turn most industrial metals into liquid.

In its most basic form, the arc welding circuit consists of an electrode, often wire, that carries a current between itself and the metal being worked on. A work cable is connected to the metal, which creates a full circuit for the electricity to run through. The power source supplies electricity to the electrode, and this electricity shoots through the space between the electrode and the metal.

At the extreme temperatures of arc welding, metals can have certain unfavorable reactions with chemicals in the air, such as oxygen and nitrogen. These reactions can weaken and corrode metal, which would harm the bond and create a weak point in a structure. To help protect against the corroding influence of outside chemicals, many arc welding techniques use what is called arc shielding. This is done by creating a gas or vapor shield around the arc, which minimizes contact between the liquid metal and the harmful chemicals in the air. This process not only protects the molten metal, but may also add stability to the arc, which improves the quality of the welding.