Flexible and highly dynamic beam shaping for Laser-Based Powder Bed Fusion of metals

Abstract

In state-of-the-art laser-based powder bed fusion processes, a thin layer of metal powder is typically melted by means of a small, Gaussian-shaped laser spot, limiting the stability and productivity of the process. The application of alternative beam shapes is a current research topic to stabilize, accelerate and extend laser-based powder bed fusion of metals, e.g. by tailoring the microstructure. Static beam shapes and sizes limit the theoretically possible process and geometry freedom. To overcome those limitations, an approach for flexible and highly dynamic beam shaping is presented. The experimental setup is based on two perpendicularly oriented acousto-optic deflectors. A synchronized superposition of the ultrafast deflections (switching rates above 100 kHz) is used to generate sequentially compound quasi-static beam shapes. This quasi-static beam shaping is combined with a state-of-the-art beam deflection system and proved to be a viable solution for improved processing. Specimens with a relative density of more than 99.5 % could be manufactured by applying three selected beam shapes. The proof of concept demonstrates the potential of the setup for flexible, fundamental research on the influence of alternative beam profiles in laser-based powder bed fusion of metals.