Additive Manufacturing: Equipment, Instrumentation and In-Situ Process Monitoring: Equipment, Instrumentation and In-Situ Process Monitoring III
Sponsored by: TMS Additive Manufacturing Committee
Program Organizers: Ulf Ackelid, Freemelt AB; Joy Gockel, Colorado School Of Mines; Sneha Prabha Narra, Carnegie Mellon University; Ola Harrysson, North Carolina State University
Wednesday 2:00 PM
October 12, 2022
Room: 304
Location: David L. Lawrence Convention Center
Session Chair: Joy Gockel, Colorado School Of Mines
2:00 PM Invited
In-situ Process Monitoring of Laser Powder Bed Fusion Additive Manufacturing Using Thermionic Emission Detection: Aiden Martin1; Philip DePond1; John Fuller1; Saad Khairallah1; Justin Angus1; Gabe Guss1; Manyalibo Matthews1; 1Lawrence Livermore National Laboratory
In-situ process monitoring is required to improve the understanding and increase the reliability of additive manufacturing (AM) methods such as laser powder bed fusion. Here we discuss a methodology based on the thermally induced emission of electrons - thermionic emission - from the metal surface during laser heating. Experimental studies show that thermionic emission signatures are correlated to laser heating conditions that give rise to pore formation and regions where surface defects are pronounced. Thermionic sensor signals collected during processing monitoring of small scale part builds will be presented and compared to conventional photodiode based sensors. The information presented here is a critical step in furthering our understanding and validation of laser-based metal AM and demonstrates that the collected thermionic signals can be incorporated into conventional data collection methodologies. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
2:40 PM
Real-time, High-speed and High-resolution Multi- and Hyperspectral Imaging of Powder Bed Fusion: Steven Storck1; Mark Foster2; Nathan Drenkow1; Brendan Croom1; Milad Alemohammad2; Christopher Stiles1; Bobby Mueller1; Michael Pekala1; Mary Dafron1; Ryan Carter1; Dylan Madisetti2; 1JHU/APL; 2Johns Hopkins University
Laser-powder-bed-fusion (L-PBF) has become a prime candidate for the aerospace and medical fields, which have challenging qualification requirements. Stringent qualification/certification standards are the main limiting factors for part acceptance, resulting in significant time and >60% of the cost to develop a final component. Real-time monitoring of L-PBF to detect defect formation and processing anomalies will significantly increase engineering certainty. This will significantly reduce qualification and certification costs and time, enabling AM in more applications and industries. Our team developed a custom high-speed hyperspectral sensor and high speed multicolor pyrometer that tracks the thermal signature of the laser melt pool at up to 500 KHz. Data is correlated with spatial porosity and analyzed with machine learning, correlating spectral characteristics to process anomalies. This talk will cover sensor development, detection of laser-induced defects and thermal anomalies using hyper- and multi-spectral imaging, machine learning analysis, and validation using 3-dimensional X-ray computed tomography analysis.
3:00 PM
Instrumenting an EOS M290 with a Smart Build-Plate: Adam Hehr1; Mark Norfolk1; Ben Stefanko1; Jason Riley1; Megan Bax2; Plamen Petkov2; Ryan Zvanut2; Tristan Cullom2; 1Fabrisonic LLC; 2Kansas City National Security Campus
Ultrasonic Additive Manufacturing (UAM), a 3D metal printing technology, uses ultrasonic energy to produce metallurgical bonds between layers of metal foils near room temperature. This low temperature attribute of the process enables integration of temperature sensitive components, such as thermocouples, directly into metal structures for thermal event monitoring. In this study, a grid of thermocouples was built into an EOS M290 SS316 build-plate to monitor temperatures during a print job. High temperature tri-axial accelerometers were mounted to the underside of the build-platform to measure vibration events in parallel with thermal profiles, e.g., recoater strike. Both thermal and vibration data was sampled during a M290 print to quantitatively monitor the build process. A future outlook on the technology and its applications is described.
3:20 PM Break
3:40 PM Invited
Microstructure Control during Wire and Arc Additive Manufacturing: Joao Oliveira1; 1FCT-UNL
Control the grain structure and process-related defects during fusion based additive manufacturing is nowadays fundamental. The development of process variants based on wire and arc additive manufacturing (WAAM) is required to further expand the potential of this technology. In the presentation, recent developments on WAAM will be presented, namely hot forging WAAM and in-situ inoculation. For the former, the intend is to performed viscoplastic deformation during the process to induce recrystallization and break the columnar structures that are easily formed. For the later, the goal is to provide nucleation points that can generate smaller grain size in the fabricated parts, while controlling the inoculants dissolution to modify the solidification path. This work will combine process development, microstructure and mechanical characterization, as well as simulation efforts.
4:20 PM
Investigating the Use of In-situ Weld Pool Characteristics and Temperature Measurements for Monitoring Part Quality in Wire Arc Additive Manufacturing: Ryan Utz1; Jack Beuth1; Chris Pistorius1; Sneha Narra1; 1Carnegie Mellon University
Real-time monitoring is desired to reduce the time and money required to evaluate parts in wire arc additive manufacturing processes. This work focuses on in-situ process monitoring of a Lincoln Electric SculptPrint RND system using weld pool dimensions and temperature measurements of the part. A video camera is attached to a robot arm and pointed at the weld pool to monitor weld pool characteristics, and an IR camera is placed at a static location next to the part to monitor heat build-up across the build geometry. Temperature and weld pool measurements are monitored for inconsistencies using machine learning algorithms and data is compared to defects identified after printing to correlate process variables with defect formation. Key process variables are identified for developing process maps and defect-free process windows.
4:40 PM
Optimization of Laser Powder Bed Fusion AM through Process Gas Control : Jacque Berkson1; Antonio Ramirez1; 1The Ohio State University
Laser Powder Bed Fusion (LPBF) additive manufacturing (AM) has the distinct advantage of producing complex parts with fine feature resolution due to the high energy density power source and fine powder feedstock. This work seeks to inform opportunities LPBF users may experience by moving away from standard usage of Argon and Nitrogen as process gases. Building upon extensive literature regarding gases used in laser welding, efforts to advance the LPBF process include the manufacture and analysis of thin-wall structures, as well as implementation of modelling and fume analysis techniques. As these methodologies provide a comprehensive analysis of laser-material interactions under varying atmospheric conditions, differences in solidification behavior and part morphology are investigated. Results from this work are expected to include valuable characterization of the LPBF process for future development, as well as expand of capabilities of existing LPBF systems currently in service.
5:00 PM
Exploring Synchronized Dual Laser Scan Strategies for Increased Productivity of Laser Powder Bed Fusion: Lars Vanmunster1; Tom Kerkhofs1; Bey Vrancken1; 1KU Leuven
While Laser Powder Bed Fusion has seen significant academic interest in the past decades, the industrial applicability is still limited to high-tech industries due to the high production time and corresponding costs of the process. To reduce the build times, multi-laser systems are quickly becoming the go-to industrial solution. However, the production speed increase is less-than-linearly dependent on the number of lasers, due to non-scaling effects such as the recoating time or non-ideal part partitioning between the lasers. We will discuss how a dual laser system can create an elliptical-like spot, reducing the energy waisted on heating powder below the melt point. First, simulations will show this strategy could increase the theoretical build speed up to 2.5 times relative to a single laser system. Then, we will describe the syncronisation challenges and explain how the interaction between lasers operating in close proximity can be leveraged.