Laser-based powder bed fusion additive manufacturing of thinner walls through re-melting

Abstract In laser-based powder bed fusion (PBF-LB) additive manufacturing (AM), the implementation of thin-walled structures (TWS) presents many advantages such as light weighting and increasing heat transfer efficiency in heat exchangers. However, PBF-LB AM of small features approaching the size of the melt pool, such as TWS, is associated with large geometric variability and increased defects. This is a consequence of using a global “contouring and filling” toolpath strategy which applies laser toolpaths irrespective of the feature size. Alternatively, it is hypothesized that a tailored laser toolpath strategy that incorporates adjusted laser scan paths allows for better control of the weld tracks to achieve thinner walls and reduce defects and build errors. To validate this hypothesis, we explore an alternative laser toolpath strategy specific to fabricating TWS via PBF-LB AM. We construct an implicit model of wall thickness as a function of laser parameters and wall inclination angle. Additionally, we quantify the effects of laser scan strategy, laser power, laser scanning speed, and inclination angle on through-porosity. Finally, we propose a generalizable method for finding the thinnest porosity-free wall achievable by using a non-dimensional enthalpy of welding approach.