Ultra-short pulse laser radiation (USP) is applied in subtractive high-precision laser material processing, whereby controlled ablation with minimal thermal damage to the components is achieved. In this study, the laser radiation is employed in the context of additive manufacturing, specifically laser-based powder bed fusion (PBF-LB) of borosilicate glass powder materials. The investigations are focused on a comprehensive analysis of the key process parameters, in relation to the material-specific properties of the glass powder. A minimum process temperature of TP = 800 °C is determined to be necessary for the manufacturing of dimensionally stable and dense components. Preheating the powder bed to Tpowder = 400 °C reduces temperature variations between the powder bed and the interaction zone, thereby enabling local heat accumulation and preventing crack formation. High-temperature microscopy identified material-specific viscosity fixed points that align closely with experimentally determined process windows, thus aiding in process control. Cross-sectional analyses of the components reveal the feasibility of achieving consolidated, closed-porosity structures with component densities ρ > 90%. An increase in component density correlates with reduced dimensional accuracy due to the formation of a consolidation zone affecting thermal conduction and powder adhesion. This indicates the capability to manufacture components with rotationally symmetric cavities of up to d = 0.4 mm at a density of ρ = 85%. The study demonstrates the potential of the PBF-USP-LB process for the fabrication of high-density glass components and provides fundamental insights into the underlying process mechanisms that support further advancement of this innovative manufacturing technology.
Kaden et al. (Fri,) studied this question.