3D printing, particulalry laser-powder bed fusion or L-PBF, requires a great deal of monitoring to avoid defects and flaws in the final parts.In a thesis entitled “Process Monitoring for Temporal-Spatial Modeling of Laser Powder Bed Fusion,”One student, Animek Shaurya, used a high-speed camera to conduct on-site monitoring of the nickel alloy 625 3D printing process to detect melting pools, spatter and over-melting areas to improve the print quality.
Another objective of the research is to study meltpool locations and the types being generated during over melting, normal melting and under melting.There are two main types of meltpool: Type One, in which the meltpool area being processed is still within the heat-affected zone of the previous hatch scanning (or track processing); and Type Two, in which the meltpool area being processed is no longer affected by the heat from laser scanning of the previous track or hatch.
For the study, an EOS Direct Metal Laser Sintering Machine was used to 3D print nickel cubes. Experiments were designed to establish a relationship between process parameters and part quality. A high-speed camera was used to perform an in-situ process monitoring to quantitatively analyze meltpool size and understand and analyze spattering behavior.
It was shown that over melting occurs more frequently in the processing of Type One tracks than in Type Two tracks.