Why is the overall cost of CO2 welding lower than that of shielded metal arc welding?

CO₂ gas shielded welding (CO₂ welding) has a lower overall cost than shielded metal arc welding (SMAW) primarily due to its higher production efficiency, higher material utilization, lower energy consumption, lower labor costs, and simpler post-processing. The following is a detailed analysis:

High Production Efficiency

CO₂ welding uses continuous wire feeding, eliminating the need for frequent electrode changes. Welding speed is 1-3 times faster than SMAW, significantly reducing working time. For example, the work efficiency of one CO₂ welder is equivalent to that of three SMAW welders.

High Material Utilization

CO₂ welding achieves a wire deposition efficiency of over 90%, while SMAW only achieves 55%-65%. Electrode coating and the welding head (approximately 5 cm) are wasted, but CO₂ welding wire has no such waste. Although the unit price of the welding wire may be slightly higher, the actual filler metal cost is lower.

Low Energy Consumption

CO₂ welding boasts a high current density and high melting efficiency, resulting in approximately 30% lower power consumption per unit weld length compared to shielded metal arc welding (SMAW). Inverter welding machines offer even greater energy savings.

Low Labor Costs

CO₂ welding eliminates the need for drying welding electrodes, frequent electrode replacements, or slag cleaning, reducing auxiliary time and labor requirements. For example, SMAW requires ovens, insulation containers, and electrode tip processing.

Simple Post-Welding Processing

CO₂ welding eliminates the need for slag cleaning, while SMAW requires frequent slag removal, increasing costs associated with grinding and other processes. Furthermore, CO₂ welding is less sensitive to rust and oil on the workpiece, requiring less stringent pre-welding cleaning.

Other Cost Advantages
Low Gas Costs: CO₂ gas is relatively inexpensive.

Equipment Maintenance: While the initial investment in CO₂ welding equipment is higher, its long-term cost advantages are significant.

In summary, CO₂ welding has lower overall consumption in terms of materials, labor time, and energy, and its long-term cost advantage is obvious.