Power-modulated wobble scanning in PBF-LB/M for periodic porous lattice fabrication

This study integrates square-wave power modulation with wobble-based scanning (WBS) in laser-based powder bed fusion of metals (PBF-LB/M) to fabricate periodic porous lattices while mitigating pore clogging at small wobble widths. Unlike on/off pulsing, the implemented square-wave modulation alternates between two prescribed non-zero power levels (e.g., a low baseline and higher peak power). Experiments were performed using Fe-79Ni-4Mo powder on a laboratory PBF-LB/M platform. Lattice morphology was characterized by optical microscopy. Pore-scale porosity was quantified by image analysis, overall porosity was measured using an Archimedes method, and melt-pool area was monitored coaxially using CMOS imaging. Compared with continuous-wave (CW) emission, square-wave power modulation enabled through-pore formation, reduced in-pore spatter size, and increased overall porosity. Melt pool monitoring showed markedly smaller melt pool areas under modulation, with area increasing with baseline power and layer count. These results indicate that power modulation reduces melt-pool size, thereby enabling smaller porous lattices using WBS-based PBF-LB/M.