Page 79 - MSAM-1-3

Materials Science in Additive Manufacturing

ORIGINAL RESEARCH ARTICLE
Increasing density and mechanical performance

of binder jetting processing through bimodal
particle size distribution

2
2
2
Ana Paula Clares , Yawei Gao , Ryan Stebbins , Adri C.T. van Duin ,
1
1,2
Guha Manogharan *
1 Additive Manufacturing and Design Graduate Program, The Pennsylvania State University,
University Park, PA 16801, USA
2 Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA
16801, USA

Abstract
Binder jetting is an additive manufacturing (AM) technology that has gained popularity
and attention in recent years for production applications in tooling, biomedical,
energy, and defense sectors. When compared to other powder bed fusion-based AM
methods, binder jetting processes powder feedstock without the need of an energy
source during printing. This avoids defects associated with melting, residual stresses,
and rapid solidification within the parts. However, one of the challenges of this
process is the relatively lower densities which impacts part density, and subsequently,
sintering and mechanical properties. In this study, we investigated the influence of
*Corresponding author: bimodal powder size distributions (a mixture of coarse to fine particles) as a method
Guha Manogharan for increasing part density and mechanical strength, and used stainless steel (SS)
(gum53@psu.edu) 316L bimodal mixtures in this case. Four unimodal and two bimodal groups were
Citation: Clares AP, Gao Y, evaluated under similar AM processing conditions for sintered density measurements
Stebbins R, et al., 2022, and flexural strengths. Our results demonstrated that bimodal size distributions
Increasing density and mechanical
performance of binder jetting showed a statistically significant increase in density by 20% and ultimate flexural
processing through bimodal particle strength by 170% when compared to the highest performing unimodal group. In
size distribution. Mater Sci Add addition to experimental findings, reactive molecular dynamics simulations showed
Manuf, 1(3): 20
https://doi.org/10.18063/msam.v1i3.20 that the presence of finer powders along with coarser particles in the bimodal particle
mixture contribute to additional bonds that are stronger across the particle interfaces.
Received: August 26, 2022
Findings from this study can be used to design bimodal particle size distributions to
Accepted: September 15, 2022 achieve higher density and better mechanical properties in binder jetting AM process.
Published Online: September 29,
2022
Keywords: Binder jetting; Bimodal powder; Mechanical strength; Molecular dynamics;
Copyright: © 2022 Author(s). 316L stainless steel; Additive manufacturing
This is an Open Access article
distributed under the terms of the
Creative Commons Attribution
License, permitting distribution,
and reproduction in any medium, 1. Introduction
provided the original work is
properly cited. Binder jetting was developed in the early 1990s and is one of the seven additive
Publisher’s Note: Whioce manufacturing (AM) technologies. Similar to direct energy deposition (DED) and
Publishing remains neutral with laser powder bed fusion (LPBF), this technology processes powder feedstock for the
regard to jurisdictional claims in
published maps and institutional fabrication of parts. The process begins with powder dispensing with a rake or blade
affiliations. or rotating roller to spread a thin layer of powder on a build platform. Next, the binder

Volume 1 Issue 3 (2022) 1 https://doi.org/10.18063/msam.v1i3.20