There is a vast variety of welding electrodes, each differing depending on the task it is meant for and how it affects the welding process. Electrodes are made to deal with a specific kind and range of electrical current and come with different coatings and in different sizes depending on the welder's requirements.
Electrodes produce the current needed for arc welding to take place. They are generally in the shape of long rods or stable wires, with a contact point at the tip of the rod that is used to channel a powerful electrical current into the metal. When the tip of the electrode nears the metal, the current jumps into the metal, creating the dazzling arc from which arc welding receives its name. This is turn creates the heat that melts the metal.
Electrodes are rated according to a system designed by the American Welding Society, using a letter, such E, followed by series of four or five numbers. Often, the diameter of the electrode is also expressed in inches before the identification, so the entire code looks like 1/16-inch E6010. This electrode has a diameter of 1/16th inch (the smallest electrodes are rated) and is used for arc welding (shown by the "E"). The number system shows what the tensile strength of the electrode is by the first two numbers, while the latter numbers show what type of coating the electrode has and what currents it can be used with. Sometimes other letters or numbers are added to show specific information.
Consumable electrodes slowly burn away as they are used, and need to be replaced at regular intervals. These electrodes are purchased in bulk and are much less expensive than the permanent versions. They are generally considered to be easier to use, but do not have many commercial uses. While a gas may be used in addition to the electrode to help shield the weld, it is not always necessary with consumable electrodes because of the gases their burning produces.
Consumable electrodes are coated with chemicals known as flux. Most flux coatings are designed to create a smoother, protected weld. As the flux burns it produces a small cloud of gas, shielding the weld from oxygen and other contaminants that can ruin its cooling process. The metal of the consumable electrode is also burned and added to the weld to help with stability. There are many different kinds of flux coatings with slightly different effects to choose between.
Nonconsumable electrodes to not burn away as they channel the electric current and last much longer. Nonconsumable electrodes, such as tungsten rods, are considered more difficult to use than consumable versions, and must be used with a shielding gas. This gas can be one of several compounds and is spread out at the site of the weld to perform the same protection tasks that the flux does in consumable models. Nonconsumable electrodes can be used with a wider variety of metals, especially the heavier metals.