Laser Powder Bed Fusion (LPBF) is a critical additive manufacturing process known for its accuracy and complexity in producing intricate parts. However, challenges like limited production speed, hot cracking, and material restrictions hinder its efficiency. This study explores the use of Multi-Plane Light Conversion (MPLC) as a beam shaping solution to improve LPBF. By applying MPLC, we achieve faster printing while maintaining high-quality parts. Comparative analysis demonstrates the superiority of MPLC-based beam shaping in enhancing process yield and manufacturing efficiency.
In recent years, Laser Powder Bed Fusion (L-PBF) has become an industrially established manufacturing technique due to the possibility to manufacture highly complex parts without additional tools. State-of-the-art L-PBF machines use single-mode fiber lasers in combination galvanometer scanners due to their broad availability, high dynamic capability and excellent focusability. To increase system productivity the manufacturing task is parallelized by the utilization of multiple laser-scanner-systems leading to increased machine costs. Alternative approaches for the scaling of L-PBF productivity such as beam shaping and variable laser beam diameters for the use of higher laser powers (PL < 400 W) are hardly used in L-PBF machines. In consequence the high peak intensities of Gaussian intensity distribution with ds = 50 – 100 μm of state-of-the-art L-PBF machines limit the usable laser powers due to the risk of part defects resulting from keyhole formation. Hence, non-Gaussian intensity distribution such as ring-mode laser beams as well as laser beam diameter variation exhibit great potential for high-power L-PBF systems. As part of the Digital Photonic Production (DPP) Research Campus funded by the BMBF L-PBF machine setups with a switchable ring-mode fiber laser and a defocused Gaussian laser intensity distribution were developed, validated and compared for the processing nickel-base alloy 625. By implementation of these approaches build-up rates up to 150% higher than those of conventional L-PBF machines were achieved while maintaining relative densities above 99.9%.
In recent years, Laser Powder Bed Fusion (LPBF) has become an industrially established manufacturing technique due to the possibility to manufacture complex part geometries without additional tools. State-of-the-art LPBF machines feature a combination of (multiple) fiber lasers and galvanometer scanners due to their high dynamic and excellent focusability, leading to significant investment costs. Highly efficient high-power diode lasers (HP-DL) could present an alternative for L-PBF machines. However, the lower beam quality (BPP > 8 mm · mrad) and spectral width (920 – 1050 nm) of commercial HP-DL results in chromatic aberrations and reduced focusability, thus making modifications to LPBF machines necessary. Current approaches to address these challenges rely on a combination of fixed focusing optics with a gantry-based positioning system resulting in less dynamic laser positioning and thus reduced system productivity and part quality. In this study an optical system, featuring a standard galvanometer scanner and a color corrected f-theta lens, is developed and integrated into a LPBF lab machine. The resulting machine configuration is combined with a fiber coupled HP-DL and used for the manufacturing of test specimen out of stainless steel AISI 316L. The manufactured parts using this approach are analyzed in terms of surface roughness, detail resolution and part density as well as build-up rate and compared with state-of-the-art LPBF-machines.
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