Why is thin wire used in CO2 welding?

The reasons for using thin wire in CO2 welding are primarily related to the characteristics of the welding process, the type of droplet transfer, and the quality requirements. The following is a detailed analysis:

1. Droplet Transfer Type and Arc Stability
In CO2 gas shielded welding, thin wire (typically less than 1.2mm in diameter) primarily utilizes short-circuit transfer. Short-circuit transfer is characterized by arc stability, minimal spatter, high droplet transfer frequency, and superior weld formation. During short-circuit transfer, thin wire can better control droplet size and frequency, thereby ensuring welding stability. Furthermore, thin wire offers lower arc voltage and current, making it suitable for welding thin plates and all-position welding, while also requiring less skilled welders.

2. Welding Parameter Matching and Spatter Control
Spatter in CO2 welding is one of the main technical issues hindering its widespread adoption. Thin wire, with its lower current and voltage parameters, can reduce spatter caused by mismatched droplet transfer. Furthermore, the use of thin wire facilitates arc self-regulation, automatically matching arc voltage and current to maintain a stable welding process. For example, in arc self-regulation systems, thin wires offer greater sensitivity, enabling faster response to parameter changes, thereby reducing defects such as spatter and porosity.

3. Welding Quality and Efficiency
When welding with thin wires, the molten pool is smaller and the heat-affected zone is narrower, resulting in less workpiece deformation and better weld quality. Furthermore, the use of thin wires in conjunction with a short-circuit transfer method achieves higher production efficiency, making it particularly suitable for welding thin plates. Furthermore, the welding process generates less light radiation, heat radiation, and welding fume, making it safer. In contrast, coarse wires typically use a fine-particle transfer method, which, while more efficient, results in greater spatter and requires stricter welding parameter matching.

4. Process Adaptability
The arc voltage in CO2 welding is generally selected based on the wire diameter. Thin wires correspond to lower arc voltages, which align with the process requirements of short-circuit transfer. Furthermore, the use of thin wires expands the application range of CO2 welding, enabling it to be used in a wider range of materials and welding positions, including all-position welding.

In summary, the reason why thin wire is used in CO2 welding is to optimize the droplet transfer form, control spatter, improve welding stability and quality, and meet the needs of thin plate and all-position welding. These characteristics make thin wire a common choice in CO2 welding.