Arc welding is a prominent form of welding used across various industries, including automotive, shipbuilding, construction, and aerospace. The process entails using concentrated heat generated by an electric arc to weld metals together.
The arc occurs from the base material to the electrode, the welding rod or wire, and melts the metal. Then the welder can fuse the molten metal and craft it into a weld.
Most arc welding processes are either consumable or non-consumable electrode methods, which determines the role of the electrode, and whether it melts to become part of the weld or solely acts as an arc conductor without melting.
While many other welding processes use gas, arc welding uses electricity, with some types requiring either direct currents (DC) or alternating currents (AC). Although, some types of arc welding require gas shielding to protect the arc against contaminants.
Taylor Studwelding has put together a guide on the different types of arc welding to help you determine which process is the most suitable for your application.
Shielded metal arc welding (stick welding)
The electric arc is generated, by either an AC or DC current, between the flux-covered consumable electrode and workpiece material. The filler materials then melt into a molten pool and fuse the metals. The electrode’s flux coating decomposes into a shielding gas during heating.
This process is popular as it’s inexpensive and uncomplicated, but it can be slower.
Gas metal arc welding (MIG or MAG welding)
This process forms a direct current (DC) electric arc between a consumable wire electrode and the workpiece materials, which melts them together and causes them to fuse. Shielding gas is fed through the welding torch to protect the arc.
MIG welding refers to using metal inert gas as a shielding gas, whereas the MAG welding technique uses metal active gas.
This process was initially developed for non-ferrous metals such as aluminium but then became commonly used for welding various materials, including thin sheets. The process is simple, economical, versatile, and easily automated.
Flux-cored arc welding
A similar process to MIG welding, but instead of shielding gas, it often uses a flux-filled hollow electrode wire. However, non-emissive fluxes may need shielding gas.
There are two types of flux-cored arc welding:
- Self-shielded – relies on the gaseous protection from the flux-cored electrode and the slag system to shield the molten metal from the atmosphere.
- Gas-shielded – uses external shielding gas and the slag system to protect the arc from oxidation.
This method is ideal for thicker joints due to the high weld-metal deposition rate, strong weld penetration, and constant voltage welding power supply.
Common uses for flux-cored arc welding include manufacturing plants, bridge construction, heavy equipment repair, industrial piping, and railroads.
It has a flexible torch movement and orientation, making it easy for users. However, the weld isn’t usually visually pleasing. It can cause slag inclusion (the result of molten flux getting trapped inside weld) and is costlier due to the equipment needed.
Gas Tungsten Arc Welding (TIG welding)
This method uses a non-consumable tungsten electrode and constant current power source to create a plasma arc between metals and can be conducted with or without filler material. Inert shielding gas protects the weld area and electrode from the atmosphere.
TIG welding can be difficult to learn and technically demanding. It requires more operator control than similar processes, but there are both manual and automatic methods available.
The process produces high-quality, clean, and strong welds but can be time-consuming. It’s primarily suitable for welding thin materials and non-ferrous metals but isn’t ideal for thicker metal joints.
Plasma arc welding
This type of welding uses ionised gases and electrodes to form hot plasma jets. It’s similar to TIG welding, but the plasma arc is separate from the shielding gas envelope due to positioning the electrode within the body of the welding torch.
Plasma arc welding is ideal for narrow and deep welds because the jets are particularly hot, enabling increased weld speeds.
Carbon arc welding
An electric arc forms between a non-consumable carbon electrode and the workpiece, joining the metals and creating a solid bond. This method was the first type of arc welding to be discovered and was previously commonly used. However, this process has since decreased due to the enhanced safety and convenience of modern techniques.
Submerged arc welding
This technique forms an electric arc between the workpiece and a continuously fed electrode. A layer of flux powder covers the arc and provides protective shielding gases and a slag, which can add alloying elements to the molten pool. The flux layer also prevents sparks and spatter and reduces heat loss.
After welding, a flux hopper can recycle unused flux and remove the slag layers.
This process, which the welder can operate as automatic or semi-automatic, allows deeper heat penetration but is restricted to steels and horizontal welds.
Atomic hydrogen welding
An arc generates between two tungsten electrodes, with hydrogen used as a shielding gas, and travels through the hydrogen gas, causing it to dissociate into atomic hydrogen.
A skilled operator is required to control the heat produced and the flow of the hydrogen gas and the arc. This process produces quick results but is rarely used as it’s expensive, involves highly inflammable gases, and is limited to flat positions. MIG welding is usually preferred.
This method is a combination of arc welding and resistance welding. A wire is fed into the welding area, and flux is added to the electrical arc until the molten slag covering on the weld surface reaches the electrode and ignites the arc. The electric resistance from the molten slag melts the filler metal and creates a molten pool on the joint surface.
Electroslag welding is ideal for welding thick materials, such as low carbon steel, due to a large amount of heat. The welder performs this process in a vertical – or close to vertical – position.
Drawn Arc (DA) stud welding
This method is generally considered a form of stud welding due to the equipment used, but the process involves producing an electric arc.
Using a Drawn Arc welding tool or gun, the welder places the stud against a base metal, which triggers a pilot arc and lifts the stud to a pre-set height. The Drawn Arc melts the stud’s base and the parent material, creating a molten pool. The return pressure forces the stud into the molten pool, and the ceramic ferrule detains the molten metal and establishes the weld.
This process produces extremely strong welds, making it most beneficial for thick parent materials. It’s also suitable for use on uneven and flawed surfaces. Compared to Capacitor Discharge (CD) stud welding, DA is more expensive and time-consuming due to the need for ferrules. However, stud welding is often deemed more beneficial than arc welding, as it’s generally more cost-effective and provides faster results.
Each type of arc welding has various benefits, disadvantages, and requirements, making them fit for specific purposes. For further guidance on which welding process is most suitable for your application, contact a welding professional.
If you’re unsure whether arc welding or stud welding is the best process for your intended function, get in touch with Taylor Studwelding for advice. The company is a leading manufacturer and supplier of stud welding machines, including Drawn Arc stud welding equipment, that provide superiorly strong welds on various metals.