Dynamic Beam Laser System Offers Real-Time Look into Melt Pool
Laser developer and manufacturer Civan Lasers has delivered an OPA 6 dynamic beam laser (DBL) to the University of Stuttgart’s Institut fur Strahlwerzeyge (IFSW). The DBL will form a system with IFSW’s high-speed x-ray video facility for laser materials-processing diagnostics. The system will enable researchers to view inside the melt pool during the laser welding process.
The in situ monitoring capabilities that the system will deliver is poised to give researchers an opportunity to improve keyhole stability in industrial welding applications.
Other in situ diagnostics that use high-speed cameras or optical sensors reveal phenomena on the surface of the process. The high-speed x-ray diagnostics system will make it possible to view the fluid dynamics occurring in process samples with high spatial and temporal resolution.
The system will specifically help researchers better understand the origin of defects, including potentially harmful defects including pores, spatter, and crackling. The x-ray imaging system can detect features below 250 μm in steel. It features maximum detection rates exceeding 10,000 Hz.
Representative example of the keyhole during laser beam welding of copper. The installation of an OPA 6 laser for dynamic beam research to the IFSW in Stuttgart will enable in situ diagnostic opportunities to improve keyhole stability in industrial welding applications. Courtesy of Civan Lasers.
“When developing improved laser-based manufacturing techniques for processes such as ablation, drilling, joining, cutting, and additive manufacturing, comprehensive diagnostics of melt pool and keyhole dynamics are crucial for understanding the interaction between laser beams and matter,” said professor Rudolf Weber, head of the process development department at IFSW. The welding of thick materials, asymmetric parts, dissimilar metals, and metals with coatings are among the materials-processing applications Weber identified as those to be supported by the system.
Civan CEO Eyal Shekel said that where conventional lasers allow manufacturers to tailor process parameters such as wavelength, pulse energy, pulse duration, repetition rate, and feed rate, DBLs from Civan, like the technology delivered to IFSW, can influence weld geometry and weld quality by stabilizing the keyhole and melt pool, as well as control and influence over the microstructure to make additional joining possibilities practical.
Civan’s coherent beam combination modulates beam shape at speeds of up to hundreds of megahertz without any moving parts, and it enables control of shape frequency, shape sequence, and depth of focus, Shekel said. Control of these parameters supports optimization of evaporation in the capillary, the flow in the molten pool, the temperature gradients near the process, and, with it, the solidification of the melt for any laser materials-processing application.
The system to be used at IFSW will increase understanding of how these new capabilities can overcome existing laser materials processing challenges such as welding dissimilar materials, crack-sensitive materials, multilayer materials, and thick materials, Shekel said.
The delivery builds on work stemming from a collaboration Civan announced last month, in which the company, with Technical University Wien scientists, partnered to simulate the Civan’s DBL technology to aid in process development, helping to optimize beam shape and frequency for a variety of laser materials-processing applications.
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