2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Binder Jet AM: Systems, Modeling, and Simulation
Program Organizers: Joseph Beaman, University of Texas at Austin
Monday 1:30 PM
August 14, 2023
Room: 602
Location: Hilton Austin
Session Chair: Nathan Crane, Brigham Young University; Christopher Williams, Virginia Tech
1:30 PM
A Data-driven Reverse Shape Compensation Method to Reduce Large Deformation in Binder Jet Parts: Basil Paudel1; Hao Deng1; Albert To1; 1University of Pittsburgh
Binder jet parts undergo significant deformation during the sintering, a process that facilitates densification. This sintering distortion may result in parts with unacceptable geometric accuracy. The current work proposes an approach to compensate input geometry based on mechanistic simulations using a data-driven method. A multi-step machine learning approach is proposed for the first time to learn the deformation pattern in binder jetted parts and offset for the sintering deformation. Initial geometries with several reverse scaling factors are simulated using a physics-based constitutive model to generate a training database. Once the training dataset is obtained, a dimension reduction technique is applied to extract the training dataset's features effectively. The model is trained and utilized to predict the compensated part. Finally, the proposed approach's efficacy is validated both numerically and experimentally by comparing the deformed sintered shape against the target.
1:50 PM
Does Finer Powder Get Deposited First in Powder Bed? – A Comparative Study using Simulation and Experimental Techniques: Willem Groeneveld-Meijer1; Kazi Shahed1; Matthew Lear1; Jeremy Schreiber1; Chinedum Okwudire2; Guhaprasanna Manogharan1; 1Pennsylvania State University; 2University of Michigan
Characteristics of an additively manufactured part through powder bed processes (e.g., binder jetting, powder bed fusion) are well influenced by the attributes of the powder and powder spreading process. Previous studies compared the printed part from unimodal powder and bimodal powder and showed that bimodal powder improves part density. But the distribution of the bimodal powders and their effect on the powder bed and subsequently on printed part has not been fully understood. In this study, unimodal and bimodal powder were used to experimentally study the powder particle distribution and the powder bed surface contour in the powder bed generated from the spreading process.
2:10 PM
Feasibility of Non-destructive Measurement of Powder Bed Density and Thermal Properties Using Flash Thermography: Shu Wang1; Nathan Crane1; 1Brigham Young University
In powder bed additive manufacturing, consistent powder bed density is critical to ensure high-quality, repeatable results. Additionally, the thermal properties of the powder bed may be important to the process results. A non-contact method that measures the density of the powder bed without direct contact can ensure that the density of the powder remains high during the manufacturing process and improve the print quality of the final product. However, there is a lack of effective methods for in-situ monitoring of these key parameters. This paper considers the use of flash thermography (FT) for this purpose. In FT, a flash of light rapidly heats a sample surface and the resulting temperature response measured by an IR camera. This paper will report on the application of this technique to rolled powder beds in binder jetting and discuss the criteria under which the thermal conductivity, thermal diffusivity, and packing density can be found.
2:30 PM
Insights from High-speed Synchrotron X-ray Imaging of Binder-powder Interaction in Binder Jet Printing: Jacob Lawrence1; Colton Inkley1; Christina Thorley1; Kamel Fezzaa2; Samuel Clark2; Nathan Crane1; 1Brigham Young University; 2Argonne National Laboratory
Binder Jetting (BJ) is an additive manufacturing process that enables production of complex, high-resolution parts. Understanding binder-powder interaction during the printing process is essential to optimizing the printing process, selecting appropriate process parameters, and improving final part quality. This work presents findings from high-speed imaging of the BJ process using synchrotron X-rays. During testing, five key print process parameters were adjusted including: powder material, droplet spacing, line number, powder bed packing fraction, and powder bed moisture levels. High-speed X-ray footage acquired during printing captures powder ejection above the powder bed surface and powder disturbance below the powder bed surface due to droplet impact. Interaction behavior extracted from the X-ray footage was used to help identify significant print process parameters that impact the observed binder-powder interactions and help develop understanding of the underlying physical mechanisms of binder-powder interaction during the BJ printing process.
2:50 PM
Numerical Investigation of the Spreading and Dynamic Flow Behavior of Poorly Sorted Sand Particles during Binder Jet Additive Manufacturing: Ibrahim Al Qabani1; Karin Goldberg1; Julio Silva2; Genevieve Baudoin1; Raphael Quirino2; Scott Thompson1; Drew Snelling2; 1Kansas State University; 2Georgia Southern University
During binder jet additive manufacturing, the consistency and homogeneity of the employed powder plays a crucial role in the final density and dimensional accuracy of the green part. In this study, Discrete Element Method (DEM) simulations were performed to investigate the influence of roller spreading input parameters (roller speed, traverse speed, geometry, etc.) on the dynamic flow of powder during layer spreading. Via DEM, we examine how different material properties, such as powder morphology, size distribution, surface morphology, and composition, affect the homogeneity and porosity of the spread layer, yielding accurate predictions for the green part’s density and dimensional accuracy. Today, most research focuses on simulating the dispersion of high-quality, evenly sized, clean foundry sand. This study focuses on the flow behavior of locally-sourced, raw earth sand during the spreading process to support remote additive manufacturing.
3:10 PM Break
3:40 PM
Providing Anti-counterfeiting Security in Binder Jetting through Tailored Porosity Signatures: Kazi Rahman1; Christopher Williams1; 1Virginia Tech
The democratization of digital product design, reverse engineering, and distributed fabrication enabled by additive manufacturing (AM) has made it highly vulnerable to counterfeiting. While some anti-counterfeiting measures have been proposed for a number of AM processes, none have been presented for metal binder jetting (BJT). In this work, the authors propose a novel method of anti-counterfeiting security for printed BJT parts wherein tailored regions of porosity are created within a part through selective patterning of binder. Upon sintering, the selectively applied binder forms stochastic regions of porosity within the part volume, which can be identified through non-destructive evaluation. Using this strategy, porous regions can be selectively generated and used as a unique part identifier. Cross-sectional microscopy and x-ray computed tomography verify successful creation of the embedded porous tag, and elucidate the technique’s achievable feature resolution within the volume of a printed copper specimen.
4:00 PM
Robotic Automation for Depowdering in Binder Jet Additive Manufacturing: Sarita Sepulveda1; Sun Yi1; Amy Elliott2; 1NC A&T State University; 2Oak Ridge National Laboratory
Binder Jet is an additive manufacturing technology (BJAM) that uses powdered materials, such as powdered ceramics and metals, and a binder agent. After a part is printed and cured, it becomes a green part, which would go through a process of depowdering, sintering or infiltration, before a product is finished. Currently, manual depowdering of BJAM parts is cost intensive and prohibits the technology’s wide-spread use in industry. Automation of binder jet depowdering consists of controlling a robot to grip and lift a part. In this study, we present an automation of binder jet depowdering with a robotic gripper of a novel design. Findings in literatures will be discussed about gouging limit, which would enable the robotic gripper to find the part without inflicting damage. These new findings from the experimental and theoretical findings will be done to understand the force constraints to aid in the automation process for BJAM.
4:20 PM
X-ray Computed Tomographic Study of Density Gradients within Binder Jet Printed H-13 Components: Dustin Gilmer1; Peeyush Nandwana2; Curtis Frederick3; 1UT-Oak Ridge Innovation Institute; 2Oak Ridge National Laboratory; 3Carl Zeiss Industrial Metrology
Binder Jet Additive Manufacturing (BJAM) is a versatile powder bed technique that uses a binder deposited using ink jetting to form complex components. BJAM is well suited for manufacturing at scale due to its high production rates and high resolution. It has been reported that binder-particle interactions during the deposition process result in powder particles being ejected from the powder bed. However, the impact of these ejected particles on the bulk part is not well understood. We use X-Ray computed tomography to study this in H13 steel parts as printed in the green state, as well as how it subsequently impacts the debinding and sintering behavior of the material. This information will be critical for understanding the evolution of defects in sintered components and their role on material properties as well as provide insights towards sintering kinetics of H13.