A co-axial photodiode monitoring system with high temporal resolution has been integrated into a proven test bench enabling synchronized side-view high speed X-ray imaging of melt pool dynamics and ...top-view spectral emission characterization of the melt pool. This setup enables direct observation of melt pool phenomena and correlation between the two monitoring systems which can be directly scaled to commercial systems. The work demonstrates a 92% detection rate in keyhole collapse phenomena related to defect generation in SLM. Furthermore, the impact of gas flow on monitoring signals is studied to understand the fundamental importance of gas flow in commercial systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Laser powder bed fusion is a promising technology enabling the manufacturing of complex parts such as cellular structures with superior mechanical properties. However, their fabrication is not ...straightforward, since the geometry of the melt track and the constitution of the melt pool significantly affects the dimensions of the final part. Thus, a sound understanding of the interrelation between process parameters, the melting process and the geometry of the melt track is of crucial importance in order to ensure high quality of the lattice. In this work, a scaling law is proposed that relates the width of a single melt track to process and material parameters. This is done employing dimensional analysis as well as an averaged energy balance. The predictive power of the proposed model is demonstrated based on extensive experimental data provided by the authors. Considering truss lattices, the present approach bridges the gap between manufacturing parameters and macroscopic characteristics of lattice structures. This ultimately enables a proactive adjustment of process parameters in order to tailor the lattice's geometry and the elastic properties. Moreover, the proposed modelling approach serves as a basis for an extended theory accounting for additional physical effects present in selective laser melting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
Directed energy deposition (DED) offers the ability for a high deposition rate as compared to other additive manufacturing (AM) processes generally due to the high layer thickness compared to other ...AM processes. Finite element modeling (FEM) of a DED process can predict the melt-pool and temperature profile without extensive experimentation, thus saving considerable time, material and money. In the current study, FEM of a high layer thickness DED process is developed by considering the Gaussian heat source model to investigate the melt-pool and temperature profiles under different process conditions. The current model is in agreement with the experimental data. Results showed insufficient melting at the very start of the process, but complete melting is achieved as the process continues. From the 2nd layer onwards, there is partial remelting of previous layers. The model predicted a rise in temperature and melt-pool dimensions when the power increases and the opposite effect when the scan speed is increased. It showed the accurate implementation of the Gaussian distributed heat source model for a high-layer thickness DED model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
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