| Abstract Scope |
The fundamental study of metal transfer in arc welding has been instrumental in the evolution of automated robotic welding. Through welding signals acquisition, real-time data processing, and control algorithms that monitor arc stability, the welding industry successfully implemented closed-loop control system and A.I.-based process control. As a variant of welding technology, laser wire additive manufacturing (LWAM) has successfully adopted these control philosophies to achieve industrial-scale manufacturing reliability.
Modern LWAM systems employ multiple closed-loop control algorithms to ensure consistent metal deposition, process stability, and robust deposit materials properties. GKN aerospace hot-wire LWAM process incorporates three (3) closed-loop control systems:
1. Laser-monitored layer height control by dynamically adjusting wire feed rate;
2. In-situ molten pool size monitoring by an infrared camera and control by regulating the laser power;
3. Interlayer temperature monitoring and control by a scanning infrared pyrometer to manage thermal history and microstructure of deposits.
With the assistance of the three closed-loop control systems, engineered Ti-6Al-4V structures can be manufactured while maintaining a stable bridging-mode metal transfer. The deposits exhibited a uniform microstructure dominated by the desirable acicular α-phase, smooth and flat beads, and clean surfaces free from discoloration.
The resultant tensile property dataset was subjected to rigorous statistical assessment by Battle’s MIDAS methodology, confirming a high level of process robustness and material performance consistency. These results provided crucial support to the development of AMS7009 for LWAM.
This progression, from fundamental understanding of metal transfer in welding to the industrialization of closed-loop controlled LWAM, demonstrates how welding science has enabled the large-scale LWAM systems capable of delivering both process stability and certifiable material performance. |