Gas metal arc welding, also known as metal inert gas welding (MIG), is a high-speed welding process that joins metals by creating an electric arc between a consumable wire electrode and the workpiece.
It is also known as metal inert gas welding MIG, in which an arc is struck between the workpiece and a consumable electrode, which provides filler metal for the weld.
The process can be semi-automatic or fully automatic as a constant voltage and direct current power source is most commonly used. From constructing towering skyscrapers to crafting intricate automotive components, GMAW is the go-to process for industries that demand durability and excellence.
Let’s discuss every important aspect of the gas metal arc welding technique, exploring its origin, machine setup, advantages, and applications.
History
The gas metal arc welding technique was developed in the 1940s by the Battelle Memorial Institute. Later, due to its faster welding time, it was applied to steel.
Earlier, due to the higher cost of inert gases, it was limited to use in non-ferrous materials. In 1953, the use of semi-inert gases, such as carbon dioxide, became common. During 1958 and 1959, developments were made in the welding process.
The short-arc variation of GMAW was introduced, increasing the welding versatility and making the welding of thin materials possible. In early 1960, the spray-arc transfer variation was developed, in which small amounts of oxygen were added to inert gases.
Gas Metal Arc Welding Machine Setup
Let’s discuss the machine setup of this metal inert gas welding technique below.
1. Welding Gun
The welding gun consists of a control switch, a contact tip, a power cable, a gas nozzle, a gas hose, and an electrode conduit. When you press the control switch, it initiates the wire freed, electric power, causing an arc to be struck.
The contact tip reduces spatter. It is connected to the welding power source, which transmits the electrical energy to the electrode. The gas nozzle directs the shielding gas, typically argon or a mixture of gases, which protects the weld pool from atmospheric contamination.
The trigger controls the flow of the electrode wire and the initiation of the arc.
2. Wire Feed Unit
The wire feed unit controls the delivery of the welding wire to the weld pool. This unit typically consists of a spool or reel of welding wire, a motor-driven feeding mechanism, and a series of rollers that guide the wire from the spool to the welding gun.
It allows for precise control over the wire feed speed, which is essential for maintaining the desired arc characteristics and ensuring a stable welding process.
3. Electrode Holder
There are two common types of electrode holders semi automatic air-cooled and semi-automatic water-cooled. The air-cooled holder is designed to maintain moderate temperatures by compressing air circulation.
It is used to weld lap or butt joints. On the other hand, in water-cooled holders, the only difference is that water replaces the air. It is used to weld T or corner joints.
4. Electrode
The electrode serves as the filler material and the conductor of electrical current. It is a continuous, consumable wire fed through a welding gun, which is often automatically controlled.
The electrode melts due to the heat generated by the electric arc. As it melts, it deposits material into the weld joint, creating a strong bond.
The choice of electrode material, typically matching the base metals being welded, is critical to ensuring the strength and quality of the weld.
5. Shielding Gas
Shielding gas plays a crucial role in ensuring the quality and integrity of the weld. It protects the weld pool from atmospheric contamination, specifically from oxygen, nitrogen, and water vapor.
Commonly used shielding gases include argon, carbon dioxide, and mixtures of these gases, sometimes with additional elements like helium or oxygen. The choice of shielding gas can affect the arc stability, weld bead shape, penetration, and overall mechanical properties of the weld.
How Does Gas Metal Arc Welding Work?
The metal inert gas welding process begins with feeding the wire electrode through a welding gun. As the wire feeds through the gun, it encounters an electric current that creates an arc between the wire and the base metal.
This arc generates the heat necessary to melt the wire and the base metal, creating a molten weld pool. The shielding gas, which is typically an inert gas such as argon or a mixture of gases like argon and carbon dioxide, is simultaneously expelled from the nozzle surrounding the wire.
This gas envelops the weld pool, protecting it from oxidation and other atmospheric contaminants.
What are Some Things You Should Know Before Using the Gas Metal Arc Welding Technique?
- GMAW is suitable for various metals, including carbon steel, stainless steel, and aluminum.
- Before using this welding technique, ensure the workspace is well-ventilated to avoid harmful fumes.
- The technique involves high electrical currents. Use only proper insulated tools and ensure all equipment is grounded.
- Regular maintenance and inspection of welding equipment are necessary to ensure consistent performance and safety.
- This technique is ideal for high-production environments due to its speed and efficiency.
Pros and Cons of the Gas Metal Arc Welding Process
Pros | Cons |
What is the Gas Metal Arc Welding Process Used For?
The GMAW welding technique is popular in the industrial welding process. It is commonly used by the metal sheet and automobile industry.
Due to its versatility and high-speed welding, the process is also popular for automated welding, where robots handle the workpieces to accelerate manufacturing.
The welding technique is often used to replace riveting, spot welding, or resistance welding.
Frequently Asked Questions
1. What materials can be welded with GMAW?
GMAW can weld a variety of materials, including steel, stainless steel, aluminum, and other non-ferrous metals.
2. What are the advantages of GMAW?
Advantages include high welding speed, ease of automation, clean welds with minimal spatter, and suitability for thin materials.
3. What equipment is needed for GMAW?
Equipment includes a welding machine, a wire feeder, a spool of welding wire, a welding gun, and a cylinder of shielding gas.
4. What types of shielding gases are used in GMAW?
Depending on the material being welded, common shielding gases include argon, carbon dioxide, or a mixture of both.
5. What are the common applications of GMAW?
Common applications include automotive repair, manufacturing, construction, and fabrication of metal structures and components.
Wrapping Up
Gas metal arc or metal inert gas welding is a pivotal technique in modern welding technology due to its versatility, efficiency, and ability to produce high-quality welds. By understanding its principles, equipment requirements, and applications, you can leverage this welding technique to meet diverse welding needs across various industries.
