Metal arc welding is a process of joining metals by melting them with an electric arc. There are different types of metal arc welding, such as shielded metal arc welding (SMAW), gas metal arc welding (GMAW), and flux-cored arc welding (FCAW). Each type has its own advantages and disadvantages, depending on the application, material, and desired outcome.
In this article, Megmeet will compare two of the most common metal arc welding processes: GMAW and CO2 welding. GMAW is also known as MIG (metal inert gas) or MAG (metal active gas) welding, depending on the type of shielding gas used. CO2 welding is a subtype of FCAW that uses carbon dioxide as the shielding gas.
I. What is GMAW?
GMAW works by creating an electric arc between the part and a continuous wire electrode. The electrode, which is fed through a welding gun, melts and combines with the workpiece to form a weld. A shielding gas, such as argon or a mixture of argon and carbon dioxide, is used to protect the weld zone from atmospheric contamination.
There are four primary methods of metal transfer in GMAW: globular, short-circuiting, spray, and pulsed spray. Each method has distinct properties and corresponding advantages and limitations.
Globular transfer: The electrode melts into large droplets that are transferred across the arc by gravity. This method produces high heat input, high spatter, and low penetration. It is suitable for flat or horizontal positions and thick materials.
Short-circuiting transfer: The electrode melts into small droplets that are transferred across the arc by short-circuiting with the workpiece. This method produces low heat input, low spatter, and high penetration. It is suitable for all positions and thin materials.
Spray transfer: The electrode melts into fine droplets that are transferred across the arc by an axial spray. This method produces high heat input, low spatter, and high penetration. It is suitable for flat or horizontal positions and medium to thick materials.
Pulsed-spray transfer: The electrode melts into fine droplets that are transferred across the arc by a pulsating current. This method produces moderate heat input, low spatter, and moderate penetration. It is suitable for all positions and medium to thick materials.
To grasp more knowledge of GMAW, you can read the article GMAW Welding (MIG) Basics: Definition, Types, Pros & Cons, Application. To know the top GMAW welding machine brand, you can visit the Top 10 GMAW Welding Machine Brands in the World (in 2023).
II. What is CO2 Welding?
CO2 welding is a subtype of FCAW that uses carbon dioxide as the shielding gas. FCAW works by creating an electric arc between the part and a tubular wire electrode that is filled with flux. The flux melts and forms a protective slag over the weld pool. The slag also provides additional alloying elements to the weld metal.
There are two types of FCAW electrodes: self-shielded and gas-shielded. Self-shielded electrodes do not require an external shielding gas, as the flux generates enough gas to protect the weld. Gas-shielded electrodes require an external shielding gas, such as carbon dioxide or a mixture of carbon dioxide and argon.
CO2 welding uses gas-shielded electrodes with carbon dioxide as the shielding gas. Carbon dioxide provides good penetration, low cost, and good mechanical properties of the weld metal. However, it also produces more spatter, more fumes, and more oxidation of the weld metal than other shielding gases.
III. Advantages and Disadvantages of GMAW vs. CO2 Welding
Both GMAW and CO2 welding have their own advantages and disadvantages, depending on the application, material, and desired outcome. Here are some of the main factors to consider when choosing between these two processes:
Cost: GMAW electrodes are generally cheaper than FCAW electrodes. However, GMAW also requires more expensive shielding gases than CO2 welding. The overall cost of each process depends on the type and amount of material being welded, the welding speed, the electrode efficiency, and the operator factor.
Quality: GMAW produces cleaner welds with less spatter and slag than CO2 welding. GMAW also produces lower hydrogen weld deposits, which reduces the risk of hydrogen-induced cracking in high-strength steels. However, CO2 welding produces deeper penetration and higher deposition rates than GMAW.
Versatility: GMAW can join a wide range of material types and thicknesses with different metal transfer methods. GMAW can also weld in all positions with pulsed spray or short-circuiting transfer. However, GMAW is rarely used outdoors or in areas of moving air, as it requires a stable shielding gas environment. CO2 welding can be used outdoors or in areas of moving air, as it is less affected by wind and drafts. However, CO2 welding is limited by the availability and compatibility of gas-shielded FCAW electrodes for different materials.
Automation: GMAW is easily adapted for high-speed robotic, hard automation, and semiautomatic welding applications. GMAW offers more control over the arc characteristics and the weld quality than CO2 welding. However, CO2 welding can also be automated with proper equipment and parameters.
You can choose an ideal welding process based on the upper factors, or you can buy a multi-process welding machine based on the 7 Best Multi-Process Welders of 2023 – Reviews & Top Picks to meet your different welding processes needs.
IV. Conclusion
GMAW and CO2 welding are two of the most common metal arc welding processes. Each process has its own advantages and disadvantages, depending on the application, material, and desired outcome. The choice of the best process depends on several factors, such as cost, quality, versatility, and automation. Therefore, it is important to understand the characteristics and limitations of each process before selecting the most suitable one for a specific welding project. Visit Megmeet Welding News column to learn more about welding basics, welding tips, and welding cases.
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2. Top 10 GMAW Welding Machine Brands in the World (in 2023)
3. Laser Welding Vs. Arc (TIG) Welding
4. Traditional Welding vs. Laser Welding
5. Manual Welding VS. Robot Welding
