Laser Powder Bed Fusion Additive Manufacturing In-Process Monitoring and Optimization Using Thermionic Emission Detection

Aiden Martin | 19-FS-037

Project Overview

Laser powder bed fusion (LPBF) involves the selective laser melting of metal powder particles, layer by layer, which fuse together to form a larger three-dimensional (3D) structure. Laser-based additive manufacturing approaches such as LPBF may revolutionize manufacturing of complex metal components, such as those used in the aerospace, medical, and automotive industries. However, the difficulty in producing defect-free components by metal 3D printing is a major hurdle for widespread adoption.

In this project, the emission of electrons during LPBF additive manufacturing was identified and investigated to resolve the underlying dynamics driven by laser–material interactions. The project resolved important dynamics in LPBF, including the identification of plasma-formation mechanisms, transitions between laser-induced melting modes, and stochastic precursors to defect formation. These findings were realized through implementation of electronic sensing diagnostics into an existing testbed system and harnessing capabilities developed for the time-dependent analysis of LPBF datasets. Importantly, the results advance our understanding of laser–material interactions and reveal that detection of thermionic emission can also resolve information critical to optimization of the LPBF fabrication process. The findings are critical for advancing our fundamental understanding of the LPBF process and can help ensure the requisite fidelity of fabricated components.

Mission Impact

This project developed and demonstrated cutting-edge capabilities aligned with Lawrence Livermore National Laboratory's core competency in advanced materials and manufacturing, including advancing in-situ characterization capabilities, and helping to ensure process scalability and the fidelity of fabricated components. The new detection methodology can be deployed alongside existing sensing methodologies on the Laboratory's LPBF testbed system to further understand laser-material interaction dynamics. It can also be used to validate thermal simulations at the Laboratory and offers expanded opportunities for cooperative technology development with external collaborators. 

Publications, Presentations, and Patents

Depond, P. J., et al. 2020. "Laser–Metal Interaction Dynamics During Additive Manufacturing Resolved by Detection of Thermally Induced Electron Emission." Communications Materials 1(1): 92. LLNL-JRNL-807184