Conference on Lasers in Manufacturing (LiM)
In laser-based powder bed fusion of metals (PBF-LB/M) an increase of the laser spot size by shifting the focus position (defocusing) offers the opportunity of reducing the overall scanning time as well as achieving a more stable melt pool behavior. However, the influence on porosity and surface roughness of bulk samples has received little attention so far. In this work, the influence of laser defocusing (Yb-fiber laser, minimum beam diameter of 35 μm) on part porosity as well as top and side surface roughness is investigated for additively manufactured Ti-6Al-4V. Therefore, the focusing lens position relative to its standard setting is investigated in a range between 1.2 mm and -8.7 mm. Additionally, the main processing parameters are varied and their influences and interaction effects are statistically evaluated according to the design of experiments approach. Optimum settings for low porosity and surface roughness are presented.