Welding is a crucial technique employed across various industries to join metals securely. Among the myriad welding methods available, Metal Inert Gas (MIG) welding stands out as a versatile and widely used process. In this guide, Megmeet will reveal the fundamentals, welding process, and myriad applications of MIG welding.
What is Metal Inert Gas Welding (MIG Welding)?
Metal Inert Gas (MIG) welding is an arc welding process that uses a continuous solid wire electrode heated and fed into the weld pool from a welding gun. The two base materials are melted together forming a join. The gun feeds a shielding gas alongside the electrode helping protect the weld pool from airborne contaminants. The shielding gas is usually an inert gas such as argon or helium, but sometimes a mixture of active gases such as carbon dioxide or oxygen can be used. MIG welding is also known as Gas Metal Arc Welding (GMAW) or Metal Active Gas (MAG) welding when using active gases.
MIG Welding: The Basics for Mild Steel
Process of Metal Inert Gas Welding.
Different procedures shall be conducted on different welding processes to achieve excellent welding results, and MIG welding is not an exception. Here’s a step-by-step overview of how MIG welding works:
➤ The wire electrode is fed from a spool by a motor drive through a contact tip that conducts the welding current into the wire. The wire diameter and feed speed determine the welding current and the burn-off rate of the wire.
➤ The arc is struck between the end of the wire electrode and the workpiece metal, creating a weld pool that fuses the base materials together. The arc length is controlled by the voltage of the power source, which can be constant or variable.
➤ The shielding gas flows out from a nozzle surrounding the wire, creating a protective envelope around the arc and the weld pool. The shielding gas prevents oxidation and contamination of the weld by atmospheric gases.
➤ The welder moves the welding gun along the joint line, either manually or mechanically, maintaining a steady travel speed and wire position. The welder can also adjust the welding parameters such as current, voltage, wire feed speed, and gas flow rate to suit different materials and applications.
MIG Welding: The Basics for Mild Steel
There are four primary methods of metal transfer in MIG welding, which are globular, short-circuiting, spray, and pulsed spray. Each method has different characteristics and advantages depending on the material thickness, position, and desired quality of the weld.
➤Globular transfer: The wire electrode melts into large droplets that detach from the tip under gravity and fall into the weld pool. This method produces high deposition rates but also high spatter and poor arc stability. It is suitable for thick materials and flat positions.
➤Short-circuiting transfer: The wire electrode touches the weld pool repeatedly, causing short circuits that melt the wire and transfer small droplets across the arc. This method produces low heat input and low spatter but also low penetration and poor fusion. It is suitable for thin materials and all positions.
➤Spray transfer: The wire electrode melts into fine droplets that are propelled across the arc by the electromagnetic force. This method produces high heat input and high penetration but also high spatter and high distortion. It is suitable for medium to thick materials and flat or horizontal positions.
➤Pulsed-spray transfer: The wire electrode melts into fine droplets that are transferred across the arc in pulses of current. This method combines the advantages of spray transfer with lower heat input and lower spatter. It is suitable for medium to thick materials and all positions.
Applications of MIG Welding
MIG welding is a versatile technique that can be used for both thin sheet and thick section components. It can weld various metals such as carbon steel, stainless steel, aluminum, copper, nickel, titanium, etc. It can also weld different types of joints such as butt, lap, fillet, corner, etc. Some of the common applications of MIG welding are:
➤Automotive industry: MIG welding is widely used for manufacturing and repairing vehicles such as cars, trucks, buses, motorcycles, etc. It can weld different parts such as body panels, frames, chassis, exhaust systems, fuel tanks, etc.
➤Construction industry: MIG welding is used for building and maintaining structures such as bridges, buildings, pipelines, tanks, etc. It can weld different shapes such as beams, columns, plates, pipes, etc.
➤Aerospace industry: MIG welding is used for producing and repairing aircraft components such as wings, fuselage, landing gear, engine parts, etc. It can weld different alloys such as aluminum, titanium, magnesium, etc.
➤Shipbuilding industry: MIG welding is used for fabricating and repairing ships such as cargo ships, naval vessels, submarines, etc. It can weld different sections such as hulls, decks, bulkheads, etc.
➤Manufacturing industry: MIG welding is used for making and assembling various products such as machinery, equipment, furniture, appliances, etc. It can weld different materials such as metal, plastic, wood, etc.
MIG Welding: The Basics for Mild Steel
Advantages of MIG Welding.
MIG welding offers several advantages, making it a popular choice in many industries:
➤High Productivity: MIG welding is known for its high deposition rates, allowing for the rapid completion of welding projects. This efficiency is especially beneficial in manufacturing and construction settings where speed and productivity are crucial.
➤Versatility: MIG welding can be used on a wide range of metals, including steel, aluminum, stainless steel, and more. This versatility makes it suitable for various applications and industries.
➤Clean Welds: The use of shielding gas in MIG welding results in clean and aesthetically pleasing welds with minimal spatter. This is essential in applications where appearance and quality are paramount.
➤Less Skill-Dependent: Compared to some other welding methods, MIG welding is relatively easier to learn and execute, making it accessible to a broader range of welders.
