CLADDING TECHNOLOGY SHANXI CO., LTDDual-Arc Pulse MIG Welding Dedicated Power Source Design and Experimental Analysis
Literature Overview
Published in the Journal of Welding in 2018 by Lu Lihui, Zhang Lihua, Sun Weicheng, Shi Yu, and Fan Ding, this paper presents the design and experimental validation of a dedicated power source for dual-arc pulse MIG welding. The research was conducted at the College of Engineering, Qufu Normal University, and the Gansu Provincial Key Laboratory of Nonferrous New Materials at Lanzhou University of Technology. The work was funded by NSFC (51405262) and the Qufu Normal University Science and Technology Program (xkj201406).
Process Description and Technical Motivation
Dual-arc pulse MIG welding employs two MIG arcs operating simultaneously to achieve welding characteristics that are not attainable with a single arc. The two arcs interact through the molten weld pool, creating synergistic effects on heat input distribution, metal transfer, and weld pool dynamics. The pulse waveform applied to each arc is carefully designed to optimize the interaction between the arcs and achieve desired welding outcomes.
The primary motivation for dual-arc welding is to achieve higher deposition rates while maintaining or improving weld quality. By operating two arcs simultaneously, the total heat input and deposition rate can be increased significantly compared to single-arc welding. However, the interaction between the two arcs introduces complexity in process control and can lead to arc instability, uneven metal transfer, and inconsistent bead geometry if not properly managed.
| Parameter | Single Arc MIG | Dual Arc Pulse MIG | Improvement |
|---|---|---|---|
| Deposition rate | 1.0–3.0 kg/h | 2.0–6.0 kg/h | 100–200% |
| Welding speed | 300–800 mm/min | 400–1000 mm/min | 30–50% |
| Bead width | 8–15 mm | 10–20 mm | 20–30% |
| Penetration depth | 1.0–3.0 mm | 1.5–4.0 mm | 20–40% |
| Spatter level | Moderate | Low to moderate | Reduced |
| Arc stability | Good | Requires control | Needs optimization |
Power Source Design
The dedicated power source is designed to independently control the pulse waveform of each arc while maintaining synchronization between the two arcs. The power source uses insulated gate bipolar transistor (IGBT) technology for high-frequency switching and precise current waveform shaping. Each arc channel has its own current and voltage feedback loops, allowing independent adjustment of welding parameters for each arc.
The pulse waveform design is a critical aspect of the power source. The authors investigate different pulse waveform configurations including rectangular pulses, trapezoidal pulses, and multi-level pulses. The pulse frequency, base current, peak current, and pulse duration are optimized for each arc to achieve stable metal transfer and consistent weld pool dynamics. The synchronization between the two arcs is achieved through a common timing signal that coordinates the pulse phases of both arcs.
The power source also incorporates adaptive control features that adjust the pulse parameters in real time based on arc voltage and current feedback. This adaptive control compensates for process disturbances such as wire feed speed variations, contact tip wear, and workpiece geometry changes.
Experimental Results and Analysis
The experimental results demonstrate that the dual-arc pulse MIG welding process with the dedicated power source achieves deposition rates that are 100–200 percent higher than single-arc MIG welding while maintaining comparable or better weld quality. The weld bead geometry shows improved width-to-depth ratio, and the microstructure analysis reveals refined grain structure due to the higher cooling rates associated with the dual-arc process.
The arc stability analysis shows that the dual-arc process requires careful control of the pulse synchronization and waveform parameters. Unsynchronized pulses lead to arc interaction instability and inconsistent metal transfer. The dedicated power source with adaptive control maintains arc stability across a wide range of welding conditions, including different joint configurations and welding positions.
| Defect Type | Single Arc MIG | Dual Arc Pulse MIG | Mitigation Strategy |
|---|---|---|---|
| Porosity | Low | Low to moderate | Optimize gas flow and pulse sync |
| Undercut | Low | Moderate | Adjust pulse waveform and travel speed |
| Arc instability | Low | Moderate to high | Synchronize pulses, adaptive control |
| Uneven bead | Low | Moderate | Optimize arc spacing and pulse phase |
| Excessive spatter | Moderate | Low | Optimize pulse parameters |
Engineering Practice Integration
For engineers in the cladding and bimetallic products industry, dual-arc pulse MIG welding offers significant productivity advantages for thick overlay layers. The high deposition rate enables rapid build-up of corrosion-resistant or wear-resistant overlay layers on large surface areas. The process is particularly suitable for overlaying nickel-based alloys such as Inconel 625 and Hastelloy C276 on carbon steel or low-alloy steel base materials for hydrogenation reactors and chemical processing equipment.
The dedicated power source design provides the flexibility needed to optimize welding parameters for different overlay materials and base material combinations. The pulse waveform parameters can be adjusted to control dilution ratio, bead geometry, and microstructure of the overlay layer. The adaptive control features help maintain consistent overlay quality over long production runs.
Key Questions and Reflections
The main challenge in adopting dual-arc pulse MIG welding for industrial applications is the complexity of process optimization. The number of process parameters is significantly higher than for single-arc welding, and the interactions between parameters make systematic optimization difficult. Engineers need to develop robust process development methodologies that can efficiently explore the parameter space and identify optimal settings for specific applications.
Another consideration is the equipment cost and complexity. The dedicated power source is more expensive than conventional MIG power sources, and the dual-wire feeding system adds complexity to the welding cell. The technology is most justified for high-productivity applications where the time savings from higher deposition rates outweigh the equipment costs.
Study Insights and Implications
This research demonstrates that dual-arc pulse MIG welding with a dedicated power source can significantly improve welding productivity while maintaining weld quality. The technology has clear applications in thick overlay welding for pressure vessels and heavy equipment, where high deposition rates and consistent quality are critical. Engineers should evaluate this technology for applications where conventional single-arc welding is too slow or where the productivity gains justify the additional equipment investment.