Seam Formation in Laser Beam Micro-Welding with Spatial Power Modulation

Abstract

When laser sources of high brilliance are used for the micro-welding of metals, small seam dimensions are generated. If the spatial power is modulated by a superposition of the linear feed rate and a circular-oscillatory movement of high frequency, the width of the seam is controlled by the amplitude of the circular movement. In this study, the irradiation pattern of the seam was calculated and reveals that some spots of the seam area are not irradiated, while other have been irradiated several times. The seam shapes were visualized with micro cross-sections for different laser powers, linear feed rates and oscillatory amplitudes. Thermal simulations were made to discuss the different seam shapes. A consequence of the oscillatory movement is the appearance of different solidification fronts, which are visible in the micro cross-sections.

Welding of thin stainless-steel sheets using a QCW green laser source

“…With a high beam quality single mode fiber laser emitting in continuous mode at 1064 nm, welds with high aspect ratios can be realized. The weld seam width remains an issue and is usually ≥ 0.1 mm, allowing almost no positioning tolerances 7 .…”

High-Precision Adjustment of Welding Depth during Laser Micro Welding of Copper Using Superpositioned Spatial and Temporal Power Modulation

“…This makes the one-dimensional movement of conventional laser beam micro welding two-dimensional and allows both processing wider weld seams as well as a more stable process without pore or crack formation [6][7][8][9]. Additional parameters in the welding process, such as oscillation amplitude, allow further degrees of freedom in the design of the weld seam width [10,11]. This adjusted weld seam width is mainly influenced by the movement of the scanning system, which is highly reliable and not affected by any process errors.…”