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Created on 05.10
Differences Between CO₂, MIG/MAG and Pulsed MIG/MAG Welding
Concept and Classification of Metal Gas Metal Arc Welding (GMAW)
Metal Gas Metal Arc Welding (GMAW) is an arc welding process that uses a consumable wire electrode, with externally supplied shielding gas acting as the arc medium. The gas protects the molten metal droplets, welding pool and high-temperature metal in the welding zone. According to different wire materials and shielding gases, it is classified into the following processes:
1. Classification by Welding Wire Type
- It is divided into solid wire welding and flux-cored wire welding.
- Solid wire with inert gas (Ar or He) shielding is defined as MIG welding (Metal Inert Gas Arc Welding).
- Solid wire with argon-rich mixed gas shielding is referred to as MAG welding (Metal Active Gas Arc Welding).
- Solid wire with pure CO₂ shielding is simply called CO₂ welding.
- For flux-cored wire: Arc welding using CO₂ or CO₂+Ar mixed gas as shielding gas is flux-cored wire gas shielded welding; welding without external shielding gas is named self-shielded arc welding.
2. Differences Between Standard MIG/MAG Welding and CO₂ Welding
- CO₂ welding features low cost and high productivity, yet it has obvious drawbacks such as heavy spatter and poor weld appearance. For this reason, many industrial applications adopt standard MIG/MAG welding instead.
- Standard MIG/MAG welding relies on inert gas or argon-rich mixed gas shielding, while pure CO₂ welding shows strong oxidizing properties. This fundamental difference determines their respective characteristics and application limits.
3. Main Advantages of MIG/MAG Welding Over CO₂ Welding
- Spatter reduction by over 50%: Under argon or argon-rich gas protection, the welding arc remains extremely stable. Stable arc performance is maintained during droplet transfer and spray transfer. Even in short-circuit transfer with low-current MAG welding, arc repulsion on molten droplets is greatly reduced, cutting spatter by more than half.
- Uniform and aesthetic weld bead: MIG/MAG welding ensures even, fine and steady droplet transfer, resulting in smooth, uniform and visually appealing weld formation.
- Weldable reactive metals and alloys: The welding atmosphere has weak or almost no oxidation. MIG/MAG can weld not only carbon steel and high-alloy steel, but also reactive metals including aluminum & aluminum alloys, stainless steel, magnesium & magnesium alloys. It greatly improves welding process performance, weld quality and production efficiency.
4. Differences Between Pulsed MIG/MAG and Standard MIG/MAG Welding
- Standard MIG/MAG mainly adopts spray transfer at high current and short-circuit transfer at low current. Low-current operation still suffers from heavy spatter and poor molding. Especially reactive metals such as aluminum alloys and stainless steel cannot be welded smoothly at low current.
- Pulsed MIG/MAG welding was developed to solve this problem. Its core feature is one droplet transferred per current pulse, essentially belonging to spray droplet transfer mode.
- The optimal working mode is one pulse, one droplet. Adjusting pulse frequency controls droplet transfer frequency and wire melting speed. The droplet diameter is close to the wire diameter, bringing lower arc heat and lower droplet temperature compared with conventional spray transfer and large droplet transfer.
Key benefits:
- Higher wire melting efficiency;
- Less welding fume, lower alloy element burnout and better working environment;
- Minimal or nearly zero spatter with excellent arc directionality;
- Suitable for all-position welding with good weld formation, wider weld width, shallow finger penetration and small reinforcement;
- Perfect low-current welding for reactive metals like aluminum alloys;
- Widens the usable current range of spray transfer; stable droplet transfer can be achieved from near critical spray current down to tens of amperes.
5. Disadvantages of Pulsed MIG/MAG Welding
- No process is without limitations. Compared with standard MIG/MAG welding:
- Slightly lower perceived welding productivity in routine operation;
- Higher requirements for welder skills and operational experience;
- Relatively higher cost of welding equipment.
6. Application Scenarios Where Pulsed MIG/MAG Is Mandatory
- The selection of pulsed MIG/MAG depends on welding process requirements. It is essential for the following materials and industries:
- Carbon steel: Applications requiring high weld quality and appearance, such as pressure vessels, boilers, chemical heat exchangers, central air-conditioning heat exchangers, and hydroelectric turbine spiral cases.
- Stainless steel: Low-current welding (below 200A) with strict quality and appearance standards, including locomotive parts and chemical pressure vessels.
- Aluminum & aluminum alloys: Low-current welding (below 200A) for high-standard appearance and performance, widely used in high-speed trains, high-voltage switches and air separation equipment.
- Copper & copper alloys: Almost all copper alloy welding within GMAW range adopts pulsed MIG/MAG process.
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