All About Arc Welding: Definition, Applications and More
What Is Arc Welding?
Arc welding is the use of an electrical arc to heat and melt metal so that it can be joined together. The principle of arc welding is that an electrode is held close to the metal to be joined, with an electrical voltage applied to create the arc. The intense heat generated by the electrical arc in the gap between the electrode and the workpiece melts the metals so that they can be fused together. There are a number of variations in the arc welding process: consumable or non-consumable electrodes, the direction of current flow, choice of shielding gas, and how new material is supplied to fill the gap between the metal pieces being joined. These different approaches are tailored towards specific combinations of metals and joint geometry to create strength and longevity in the weld.
All About Arc Welding: Definition, Applications and More
Many variations of arc welding exist, each with its own name. One commonly used technique is called “stick welding.” The “stick” is a consumable electrode in the form of a short, stiff rod. The arc is struck between the tip of the welding rod and the workpiece. It is manually fed into the weld zone, where it melts. A coating of flux on the outside of the welding rod generates the gas shield around the weld pool as it is consumed.
Stick welding is the most accessible type of arc welding (requiring the least specialized equipment), which is why it is sometimes used as another term for arc welding. However, it is only one type of arc welding — four other types of arc welding include: tungsten/inert gas (TIG) welding, metal/inert gas (MIG) welding, flux cored arc welding (FCAW), and submerged arc welding (SAW).
How Arc Welding Works
The arc welding process works by using an electrical arc to melt metal. An arc is created by applying a voltage across two separated conductive electrodes (one of which is the workpiece) until an electrical path is created through the air gap between them. One conductive electrode is the base metal workpiece; the other electrode is movable, either manually or automatically. The electric arc passing through the air between the two electrodes has a high temperature of over 3000 °C. This arc, therefore, heats the metal to be welded past its melting point, making a pool of molten metal at the termination of the arc. The edges of the two metals are melted, usually together with filler material from a consumable electrode, and they combine to form a single molten mixture. As the arc moves on, the melt pool cools and the metal hardens into a strong weld.
All About Arc Welding: Definition, Applications and More
The temperature of the electric arc in an arc welding process can be in the range of 3500 °C up to more than 20,000 °C! Although the temperature is very high, it is focused on a very small area of the metal surface. The high temperature of the arc means that the melting point of the metal to be welded is reached very quickly. The temperature of the weld pool itself reaches a range of 2000 to 2500 °C.
Types of Arc Welding
A few of the different types of arc welding are below. Read the linked article for more.
➤Shielded Metal Arc (SMAW) Welding: SMAW (sometimes called “stick welding”) is the most common and accessible type of arc welding. It makes use of a consumable, hand-held electrode (the “stick”). This electrode is coated with flux, which melts at the tip of the electrode and produces the shielding gas, as well as a slag product that protects the weld from oxidation during welding.
All About Arc Welding: Definition, Applications and More
➤Flux Cored Arc Welding (FCAW): This is similar to SMAW welding, but it is semi-automatic. The consumable electrode used contains flux and it is continuously fed.
➤Metal Inert Gas (MIG) Welding: This welding technique uses shielding gas to protect the molten metals from the atmosphere. The metal consumable electrode is machine-fed.
➤Tungsten Inert Gas (TIG) Welding: This welding method uses a non-consumable electrode made of tungsten, and therefore requires a filler wire to be fed to make the weld. Shielding gas is necessary.
➤Submerged Arc Welding (SAW): This strategy is used with automated welding processes, where the joint to be welded is completely submerged in flux. The flux is conductive when molten, and the weld is completed below this blanket of flux.
Applications of Arc Welding
➤Maintenance and Repair: Arc welding is a versatile method of performing repairs to metallic components. Not only can it be used for repairing cracks or attaching patches, but it can also be used for building up new material where there has been excessive wear.
➤Ship Building: Arc welding is the fundamental construction method used to join plate metal together with a watertight seal.
➤Industrial Piping: Arc welding is used in workshops and in the field to fabricate industrial piping runs of various materials.
➤Vehicle Assembly: Large automated automobile assembly plants use arc welding (typically MIG welding) to join the various parts of the vehicle frame and other components together.
