Additive Manufacturing of Metals: Equipment, Instrumentation and In-Situ Process Monitoring: Imaging and Sensing Methods
Program Organizers: Ulf Ackelid, Freemelt AB; Ola Harrysson, North Carolina State University; Joy Gockel, Colorado School Of Mines; Sneha Prabha Narra, Carnegie Mellon University
Wednesday 8:00 AM
October 20, 2021
Room: A121
Location: Greater Columbus Convention Center
Session Chair: Joy Gockel, Colorado School Of Mines
8:00 AM
High-speed Observations and Quantification of Spatter in Laser Powder Bed Fusion: Christian Gobert1; Jack Beuth1; Evan Diewald1; 1Carnegie Mellon University
Mitigation of spatter is desired to improve material performance in laser powder bed fusion processes. Quantifying spatter particles ejected from the melt pool can shed light on the phenomenon. Using a machine learning identification and tracking tool, spatter particles were quantified in high-speed videos observations of the laser powder bed fusion process. Spatter generation related to key process variables and materials is studied in the aim of developing process map approach to mitigating spatter.
8:20 AM
Advancing Measurement Science of Laser Powder Bed Fusion (LPBF) Process Monitoring Applying Thermal Imaging: Guadalupe Quirarte1; Syed Zia Uddin1; 1Carnegie Mellon University
Accurate measurement of melt-pool temperature in the laser powder bed fusion (LPBF) process would result in an enhanced process control and qualification and in high-fidelity data for process modelling input and machine learning. Both the high speed associated with the laser and the change of phases and morphology during LPBF processing make it a challenging task to experimentally measure the melt-pool temperature using conventional infrared imaging or pyrometry. We are focused on developing real-time thermal imaging of AM tool melt-pool and surroundings leveraging the principle of dual wavelength pyrometry. Data is acquired using a high-speed camera operating at a shutter speed range of 30-40 microseconds and 6400 frames per second. Unique challenges associated with the methodology and corresponding calibration efforts were also outlined. Finally, the results presented would show the melt-pool temperature fields and shapes for different commonly used LPBF materials such as Ti-6Al-4V and 316L-SS.
8:40 AM Invited
Innovative and Practical Approaches to Laser Powder Bed Fusion Sensing and Process Enhancement: John Middendorf1; 1Open Additive
While working with NASA and the DoD the Open Additive (OA) team has gained extensive experience developing or using a wide range of in situ sensing modalities, some for commercial product development and some simply for physical process understanding. This talk will highlight the capabilities and limitations of a broad range of sensors, ranging from coaxial melt pool imaging to optical tomography to exotic spectroscopy systems. Trade-offs between different in situ sensing approaches will be discussed so the types of sensors chosen for a given application, and the rationale, can be understood. To conclude, the talk will show how users can access and use live in situ data streams, and ways in which in situ sensing data may be used in the future for R&D, quality assurance, and developing new AM processes.
9:20 AM
In-situ Sensing in Processing Parameter Development for Bismuth Telluride Bulk Part Fabrication Using Laser Powder Bed Fusion: Kelly Rickert1; Joy Gockel1; Sabrina D'Alesandro1; Saniya LeBlanc2; Tanvi Banerjee1; Alexander Groeger1; Joe Walker3; John Middendorf3; 1Wright State University; 2George Washington University; 3Open Additive
Laser powder bed fusion (LPBF) additive manufacturing (AM) is a promising manufacturing technique because it can create complex components in one process with minimal waste. This study investigates process parameter development for bismuth telluride, a functional material for solid-state thermoelectric energy conversion, using in-situ process monitoring with multiple sensors during the LPBF AM process. The influence of the processing parameters (laser power, laser speed and hatch spacing) is explored by performing basic experiments on a bismuth telluride substrate, including single bead laser tracks and single area laser scans. Multi-sensor in-situ process monitoring data is collected during the printing process and the sensor data is analyzed to determine relevant features that relate to the melt pool size and material characteristics such as porosity. The results of this work will connect in-situ sensor response to material characteristics and will inform process design methodologies to accelerate the development for AM of bismuth telluride.
9:40 AM
Laser Powder Bed Fusion of Tall Thin Walled Structures: Dimensional Inaccuracy Due to Local Buckling, and In Situ Infrared Imaging for Early Failure Detection: Syed Zia Uddin1; Jack Beuth1; 1Carnegie Mellon University
Laser powder bed fusion (LPBF) fabrication of tall and thin-walled structures results in large deformation and local buckling causing the parts to violate required geometric tolerances, or even total build failure. We studied the effect of wall thicknesses on the buckling pattern and dimensional accuracy for 50mm tall and 26mm wide 2x2 cell structures with three different wall thicknesses of 200, 300, and 500μm. In addition, in situ process monitoring setup using infrared (IR) imaging and corresponding image processing tools were developed to investigate the preconditions that existed for a successful or a failed build. Three distinct local buckling patterns were observed for the three wall thicknesses and analytics on in situ IR monitoring was presented as an early build failure detection tool.