Additive Manufacturing of Metals: Equipment, Instrumentation and In-Situ Process Monitoring: On-Demand Oral Presentations
Program Organizers: Ulf Ackelid, Freemelt AB; Ola Harrysson, North Carolina State University; Joy Gockel, Colorado School Of Mines; Sneha Prabha Narra, Carnegie Mellon University
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 1
Location: MS&T On Demand
Defect Recognition and Improvement in Ti-6Al-4V Fabrication by In-situ Monitoring and Feedback System of Directed Energy Deposition LAMDA 200: Lingxiao Ouyang1; Kenta Aoyagi1; Yuji Imamiya2; Akihiko Chiba1; 1Tohoku University; 2Mitsubishi Heavy Industries Machine Tool Co., Ltd.
Directed Energy Deposition (DED), known as one of the additive manufacturing technologies, can be utilized to manufacture 3D metal parts via layer-wise cladding, and thus it provides an opportunity to manufacture complex-shaped and customized parts. Besides, Ti-6Al-4V has become one of the most widely studied alloys due to its high strength to density ratio, good corrosion resistance, biocompatibility, and weldability. We set up a coaxial camera with the nozzle (LAMDA 200, Mitsubishi Heavy Industries Machine Tool, Ltd.) for in-situ monitoring of the molten pool surface. Characteristics of the molten pool like Nozzle Brightness Ripple are applied to recognize the surface unevenness. Meanwhile, computational thermal-fluid dynamics (CtFD) simulations are also performed to analyze the melt dynamics, which agrees with results of the in-situ monitoring. Finally, a Proportional-Integral-Differential (PID) feedback system is utilized to accommodate processing parameters and thus improve the surface properties of Ti-6Al-4V fabrication.
Plenoptic Imaging for In-situ PIV and Melt Pool Monitoring in Laser Directed Energy Deposition: James Haley1; Thomas Feldhausen1; Vincent Paquit1; 1Oak Ridge National Laboratory
In Laser Powder Directed Energy Deposition, process performance critically depends on the highly dynamic bombardment of powder particles into a weld pool established by a laser energy source. To better characterize the stability of this process, we implement a plenoptic 2.0 camera in-situ to obtain real-time 3D volumetric Particle Image Velocimetry as well as melt pool topography in a single snapshot. This technique enables direct monitoring and control of the reshaping of carrier and shield gas flows as they interact with the arbitrary shape of the printed component, as well as the wetting behavior of the molten metal. This technique opens new avenues for defect recognition and predictive control algorithms to compensate for these effects. Using this method we envision a future of fully automated parameter tuning for modulating powder mixes for functionally graded materials.
Studying the Effect of Inert Gases on Thermal Behavior in Laser Powder Bed Fusion Using In Situ Monitoring and Similarity Analysis: Sujana Chandrasekar1; Fred List2; Sabina Kumar1; Keith Carver2; Jamie Coble1; Vincent Paquit2; Sudarsanam Babu1; 1University of Tennessee; 2Oak Ridge National Laboratory
Inert gas is used in laser powder bed fusion to aid with cooling and avoid formation of reactive oxides on the part surface. However, the effect of different inert gases on thermal behavior has not been studied using in-situ monitoring. In this work, we use infrared monitoring of Ti-6Al-4V lattice structures to study differences between Argon and Helium in L-PBF. Lattices enable small spatially isolated regions where inert gas effects can be studied. Similarity analysis was used to study thermal signatures. Results indicate that Helium cools faster than Argon in some lattice nodes, as expected. But, the effect is limited by the size of conduction paths at lattice nodes. With large conduction paths, Helium and Argon cool at nearly identical rates. Inert gas and geometry need to be considered together while designing process parameters to achieve desired part properties.