Detection of Nozzle Wear in High-Speed Directed Energy Deposition Using Multispectral Process Emissions

In High-Speed Directed Energy Deposition, nozzle wear affects powder stream symmetry and energy coupling, leading to reduced deposition stability and impaired surface integrity. In this study, the influence of nozzle wear on multispectral process emissions and the resulting track morphology is investigated. Single-track deposits were produced using new and worn coaxial nozzles under identical process conditions and monitored by a coaxial multispectral photometric sensor covering the visible and near-infrared spectral range.
Multispectral emission signals were analyzed using feature selection and clustering methods to distinguish nozzle conditions and identify sensitive spectral descriptors. Tracks produced with worn nozzles exhibited systematically reduced track heights and increased geometric irregularities compared to new nozzles, while penetration depth remained largely unaffected. Clustering based on selected spectral features enabled reliable differentiation between nozzle conditions with an accuracy of approximately 80%.
The results demonstrate that multispectral emission signals provide characteristic indicators of nozzle wear and correlate with surface-related quality features in HS-DED. ... mehrThis highlights the potential of photometric process monitoring for early detection of nozzle degradation and improved process stability in high-speed additive manufacturing.