Single mode fiber laser beam welding with superposed beam oscillation

Combining remote ablation cutting and remote welding: opportunities and application areas

“…In this study a penetration depth d greater than 2.5 mm was observed even at a welding velocity of 20 m/min using moderate laser power of P L = 2 kW. Figure 11: Cross-section polishes of single mode fibre laser welds (P L = 2 kW, d f = 0.05 mm) for mild steel (DC04) (left) and course of geometrical features (centre) and aspect ratio of weld seams (right) derived from a DOE model presented in [19] The processing speed is hence either limited by the decrease in penetration depth d or the occurrence of humping, which was investigated in [20,21]. The authors reported that humping tends to occur at lower welding velocities v W , when the aspect ratio of the weld seam is high, which is a given fact for single mode laser weld seams.…”

“…The application of single mode fibre laser radiation in the welding regime results in weld seam geometries, which show characteristically high aspect ratios a R (ratio of penetration depth d to weld seam width w). Figure 11 (left hand side) shows two cross-section polishes prepared in context of a design of experiments (DOE) welding study, which is explained in detail in [19]. Figure 11 centre contains the corresponding geometrical features of the weld seam, which were measured from the cross-section polishes and are estimated with the regression model from the DOE study.…”

“…In contrast the track velocity reaches its maximum at the root points and thus the energy deposition is minimal, which explains the decrease in penetration depth d in the centre part of the weld seam. A method to estimate the optimum oscillation frequency, based on analytical considerations and a DOE study, was presented in [19]. Figure 13: Cross-section polish of the weld seam, which has been welded with superposed sinusoidal beam oscillation (left) and corresponding energy deposition assuming an ideal Gaussian power density distribution (right)…”

Weld formation mechanism of fiber laser oscillating welding of austenitic stainless steel

“…5, the w decreases gradually to equal to or even smaller than double amplitudes with the increase of oscillating frequency. Schweier et al (2011) claimed that galvanometer scanner has a frequency limit related to given amplitude. Once the frequency exceeds the limit, the scanner inertia will prevent the laser beam reaching reversal points, which reduces the real amplitude to be smaller than setting value.…”