Speaker
Description
Laser Powder Bed Fusion (PBF-LB/M) enables the tool-free manufacturing of complex metallic components. However, the often-emphasized geometric freedom of PBF-LB/M is limited by the insufficient transferability of process parameters developed on simple reference geometries to real components with locally varying geometric conditions. In particular, thin-walled sections, overhangs and filigree features contain short scan vectors and reduced local heat dissipation, leading to short repetition times, geometry-induced heat accumulation and locally altered melt-pool dimensions. As melt-pool width and depth are directly linked to dimensional accuracy, surface quality, porosity formation and microstructural evolution, maintaining constant melt-pool dimensions throughout a component is considered a key target for geometry-adaptive process control. This contribution investigates the process-side fundamentals for a geometry-adaptive parameter pre-control strategy in PBF-LB/M. In contrast to closed-loop concepts based on monitoring signals, relevant process parameters are intended to be adapted before manufacturing and written into the build file instead of being actively regulated during the process. To identify geometry-dependent process sensitivities, cuboid specimens with defined scan-vector lengths and varying process parameters were monitored using coaxial photodiode and lateral optical tomography during and analyzed metallographically after the build. Pronounced deviations occurred for scan-vector lengths below approximately 3.5 mm, where heat accumulation caused melt-pool enlargement, surface elevations and reduced process robustness. This was also reflected in the relative density. The corresponding monitoring data confirmed geometry-dependent process deviations, but their correlation to part quality is not clear-cut. Comparable signal levels in different geometric sections do not necessarily correspond to identical melt-pool dimensions or relative densities. Thus, monitoring signals have to be interpreted in relation to local geometry and process history rather than as direct indicators of local temperature or part quality.
| Speaker Country | Germany |
|---|---|
| Would you like to publish your paper in the special issue of BHM "Berg- und Hüttenmännische Monatshefte" | Yes |