A welding rod is a stick of filler metal used to join materials together during the welding process. During welding, a welding machine creates an electric arc that travels out through this rod and on to the material being welded. In this way, the welding rod acts as a source of resistance, generating heat that melts the rod into a pool of molten metal. As the metal cools, it dries to form a permanent bond between two objects. Welding rods may also be known as consumable electrodes because of the way they are melted down and consumed by the welding process.
The basic welding rod consists of a base metal, such as steel or zinc, with a chemical coating designed to enhance the properties of the base metal. This coating adds strength and stability to the rod, and helps it melt smoothly and evenly during welding. By melting the metal slowly and evenly, the chemical coating helps distribute the filler metal across the entire welded area. This produces a much stronger and more durable bond that's less likely to fail.
These rods come in a range of sizes to suit the needs of different projects and welding techniques. The smallest rods measure 1/16-inch (1.6 mm) in diameter, while the largest are generally no greater than 5/16-inch (7.9 mm) in diameter. Thicker rods require higher electrical amps, which are generated by the welding machine. Generally, the thicker the material being welded, the larger the welding rod that is required for a successful project. This also means that thicker objects require larger and more powerful welding machines.
One of the most widely used systems for identifying welding rods is the American Welding Society (AWS) numbering system. Under this system, the size of each rod is stamped on its face, along with a five-digit code starting with the letter E. The first two numbers of the code let users know the tensile strength that the rod can provide during welding, while the final number indicates the type of coating used on the metal. The third number informs users how the rod can be positioned in relation to the material being welded.
Some welding rod types are considered fairly standard for certain applications. For example, an E6010 rod is designed for heavy-industrial projects, and must be welded using a direct current. An E6011 rod serves the same basic function, but can be applied using both alternating and direct currents. The E7014 is a general-purpose rod that is fast and easy to use, while the E7018 is typically reserved for high-quality and sensitive welding applications.