| Abstract Scope |
Balling is a defect in LPBF process and is primarily caused by melt pool instability. It leads to discontinuous melting, increased porosity, and poor recoating conditions. This study investigates an in-situ approach to characterize the balling effect using a high-speed coaxial camera and a laser line profiler. A total of 252 single tracks were produced on an SS316 substrate by varying laser power from 60 to 460 W and scan speed from 350 to 2000 mm/s. Balling was observed predominantly under combinations of high laser power and high scan speed. The results indicate that both sensing modalities are directly correlated with balling; however, coaxial melt pool imaging is highly sensitive to balling characterized by excessive surface area, whereas laser profiler measurements are more sensitive to balling with excessive vertical height. Neither modality alone can reliably identify all balling events. In contrast, combining both modalities enables accurate prediction of balling locations. |