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Binder jetting is a powder bed additive manufacturing process where an object is created by depositing liquid binder onto the surface of powder, selectively binding particles in each layer. The quality of the as-printed parts is influenced not only by process parameters such as layer thickness, binder saturation, print speed, and drying time but also by the location within the build box. This study highlights the location-dependent nature of green density and dimensional accuracy in the as-printed samples, and the observed trends are thoroughly discussed. A conventional powder spreading using a single roller was compared with a double roller to maximize powder packing and bed uniformity prior to binder jetting process. The significance of these observations lies in their impact on densification behavior, shrinkage, and the final geometry of the printed part.
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Spreadability of Raw Sand in Binder Jet Additive Manufacturing: Examining Feasibility Using Numerical Methods
In binder jet additive manufacturing (BJAM), uniformity and density of the powder layer impact green part quality. This study investigates the printability of unrefined sand using counter-roller spreading. Altair EDEM, a high-performance software powered by the Discrete Element Method (DEM), was used to simulate the BJAM process to evaluate powder bed homogeneity and density under various operating conditions, including roller rotational speed, traverse speed, powder layer thickness, and roller diameter. Utilizing high-performance computing (HPC) and graphics processing unit (GPU) clusters, time-efficient, and more realistic, simulations were performed simulating 300,000 grains. Detailed DEM simulations were executed by reconstructing representative particle shapes using two-dimensional images obtained using particle characterization equipment. The results highlight roller velocity and powder layer thickness as key determinants of sand spreadability. Optimal powder bed density (PBD) was achieved at a roller velocity of 20 mm/s with minimal deviation. A layer thickness exceeding 200 micrometers was found to prevent jamming and void formation, while percolation led to size segregation. The findings indicate that producing uniform and dense layers of unrefined sand is feasible but may incur trade-offs in print resolution and increased printing times. This work contributes to the advancement of sustainable and/or remote BJAM technologies, ensuring progress in both environmental sustainability and accessibility.
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- Award ID(s):
- 2423166
- PAR ID:
- 10639831
- Publisher / Repository:
- The Minerals, Metals & Materials Society: TMS
- Date Published:
- Page Range / eLocation ID:
- 159-171
- Format(s):
- Medium: X
- Location:
- Austin
- Sponsoring Org:
- National Science Foundation
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