Welding, as an important joining technology, has played a significant role in driving the development and innovation of modern industry. It ensures product quality and production efficiency in many industries, while also providing greater flexibility in design and manufacturing.
The types of welding refer to various methods or techniques used to join materials (typically metals) by melting them to form welding joints.
These methods may or may not involve the use of filler material. Different welding methods are selected based on the materials being welded, the required strength, and the environmental conditions in which the welded structure will be used.
Below, let’s explore some common types of welding:
Arc Welding
Arc welding is a method that uses the heat from an electric arc to melt metal workpieces and join them together. In arc welding, an electric arc is generated between the welding electrode and the workpiece, and the high temperature of the arc melts the metal locally, forming a welding joint.
The arc is generated by the flow of current between the electrode and the workpiece, producing high temperatures. Welding rods (filler electrodes) or other methods are typically used to provide filler metal, which fills the joint and enhances the strength of the weld. During the welding process, it is necessary to protect the weld from the influence of oxygen and moisture in the air, usually achieved through welding flux or shielding gases.
Arc welding is widely used in industries such as construction, automotive, shipbuilding, pipelines, and aerospace. It is suitable for welding different materials, especially steel and aluminum alloys.
Let’s take a look at common types of Arc Welding.
Stick Welding (SMAW)
Stick Welding (SMAW), also known as Shielded Metal Arc Welding, is one of the most common and versatile types of arc welding. In this process, an electric arc is formed between a consumable electrode (also called a “welding rod”) and the workpiece. The heat from the arc melts both the electrode and the workpiece, creating a weld pool that, upon cooling, joins the materials together.
Unlike other welding methods such as MIG or TIG welding, SMAW does not require external shielding gas because the flux on the electrode forms a protective layer during the welding process.
TIG Welding (GTAW)
TIG Welding (Tungsten Inert Gas Welding, Gas Tungsten Arc Welding, GTAW) is a high-precision welding method that uses a non-consumable tungsten electrode to create the weld joint. The process forms an electric arc between the tungsten electrode and the workpiece, melting the material and forming a weld pool. Depending on the application, filler material may or may not be used. The weld area is protected from contamination by a shielding gas, typically argon or helium.
TIG welding is favored for its high quality, precision, and clean welds, making it especially suitable for welding thin materials or complex weld joints.
MIG Welding (GMAW)
MIG Welding (Metal Inert Gas Welding), also known as Gas Metal Arc Welding (GMAW), is a common welding method that uses a continuous consumable metal electrode (welding wire) and shielding gas (typically argon or carbon dioxide) to melt and join metal workpieces. MIG welding is a semi-automatic or fully automatic welding process suitable for various materials, including steel, stainless steel, and aluminum.
Due to the use of continuous welding wire, MIG welding provides a high welding speed, making it ideal for large-scale production.
Flux-Cored Arc Welding (FCAW)
Flux-Cored Arc Welding (FCAW) is a specialized metal welding method that combines the characteristics of MIG welding (Gas Metal Arc Welding) and arc welding. It uses a special hollow welding wire (flux-cored wire) to weld metal workpieces. Unlike traditional MIG welding, FCAW uses welding wire with a flux core, which contains welding flux that provides shielding gas during the welding process and promotes the flow and bonding of the weld metal.
Due to the volatilization of the welding flux, FCAW can produce more smoke and fumes during the welding process, requiring a well-ventilated environment for welding.
Gas welding
Gas welding also known as Oxy-Acetylene Welding (OAW), is a welding method that uses a combustible gas (usually acetylene) mixed with oxygen, which is then ignited to produce a high-temperature flame that melts the metal and joins it. Gas welding is ideal for welding metals that require relatively low temperatures and is flexible in operation, making it suitable for small-scale, precise welding tasks.
Resistance Welding (RW)
Resistance Welding (RW) is a welding method that achieves metal connection through the heat generated by electric current. In the process of resistance welding, two metal workpieces are clamped between two electrodes, and electric current is passed through the electrodes. As the current flows through the metal workpieces, the resistance of the metal generates heat. This heat is sufficient to melt the contact surfaces of the metal, forming a strong welded joint.
The main types of resistance welding are: Spot Welding, Seam Welding, Projection Welding and Roll Spot Welding.
- Spot Welding: The most common type of resistance welding, suitable for welding thin metal sheets. Electric current passes through the contact points, causing local melting and forming weld spots. It is commonly used in industries such as automotive manufacturing and home appliance production.
- Seam Welding: Similar to spot welding, but the electrodes rotate continuously, forming a continuous weld joint. This method is often used for applications requiring sealing, such as pipes and containers.
- Projection Welding: Uses raised areas on the metal surface to concentrate current and pressure, creating a weld. It is ideal for applications requiring multiple welds, such as the welding of electronic components.
- Roll Spot Welding: This method applies pressure and passes electric current through two rotating electrodes. It is suitable for larger or more complex welded parts.
Laser Welding
Laser welding is a welding technology that uses high-energy laser beams as a heat source to melt and join metals or other materials. The process focuses the laser beam on the workpiece surface, generating high temperatures that melt a localized area of the metal or material, forming a weld joint once it cools. Although the equipment cost is relatively high, laser welding has become an indispensable technology in advanced manufacturing due to its outstanding performance in precise welding and complex joint applications.
Electron Beam Welding (EBW)
Electron beam welding is a technique that uses a focused high-speed electron beam to locally heat metals or other materials to their melting point and weld them together. The electron beam is generated in a vacuum environment, so this welding method is not affected by oxygen or contaminants in the air. It allows for extremely precise and high-strength welds, and is mainly used in aerospace, precision instruments, and automotive industries.
Submerged Arc Welding (SAW)
Submerged arc welding is a widely used welding method for large-scale production, where the electric arc is submerged in flux during welding. A layer of powder-like flux protects the molten pool from air contamination, improving weld quality. SAW offers deep penetration and high welding speed, and is commonly used for large metal pieces like ships, pressure vessels, and steel structures.
Brazing
Brazing is a method of joining metal parts by using a filler metal with a lower melting point than the base metals. Unlike welding, the base metal does not melt in brazing; instead, the filler metal flows into the joint by capillary action, bonding the parts together. Brazing is suitable for thin materials and joining dissimilar metals and is commonly used in electronics, electrical components, and HVAC industries.
Explosion Welding
Explosion welding is a non-traditional welding method that uses explosive force to bond two metals or materials together. During explosion welding, the force from the explosion causes the materials to rapidly come into contact and form a welded joint. The process generates high pressure and temperature but does not require a traditional heat source. Explosion welding is often used for manufacturing metal composites and joining difficult-to-weld materials like steel and aluminum alloys.
Forge Welding
Forge welding is a traditional welding method where metal parts are heated to a malleable temperature and joined together through the application of pressure. Unlike other welding methods, forge welding does not melt the base metal but instead uses pressure to bond the heated metal parts, forming a strong joint. Forge welding is widely used in the forging industry to connect heavy machinery parts, tools, and metal components.
Summary
The choice of the appropriate welding method depends on several factors, including the material type, thickness, strength requirements, production efficiency, cost, and environmental conditions. For high precision and small-sized materials, TIG welding is the ideal choice, while MIG welding and Flux-Cored Arc Welding (FCAW) are suitable for large-scale production and do not require external shielding gas. For thick materials, Submerged Arc Welding (SAW) offers higher welding speed and deep penetration. Laser welding and Electron Beam welding are suitable for precise and high-purity welding applications.
In summary, the selection of a welding method should consider material properties, welding precision, production requirements, and cost-effectiveness.
