Model Guided Mixing of Ceramic Powders With Graded Particle Sizes in Binder Jetting Additive Manufacturing

2018 ◽  
Author(s):  
Wenchao Du ◽  
Xiaorui Ren ◽  
Yexiao Chen ◽  
Chao Ma ◽  
Miladin Radovic ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Packing Density ◽  
Ternary Mixture ◽  
Sintered Density ◽  
Selection Process ◽  
Ternary Mixtures ◽  
Particle Sizes ◽  
Mixed Powder ◽  
Powder Bed ◽  
Binder Jetting

Binder jetting additive manufacturing is a promising technology for fabricating ceramic parts with complex or customized geometries. However, this process is limited by the relatively low density of the fabricated parts even after sintering. This paper reports a study on effects of mixing powders with graded particle sizes on the powder bed packing density and consequently the sintered density. For the first time, a linear packing model, which can predict the packing density of mixed powders, has been used to guide the selection of particle sizes and fractions of constituent powders. A selection process was constructed to obtain the maximum mixed packing density. In the part of model validation, three types of alumina powders with average sizes of 2 μm, 10 μm, and 70 μm, respectively, were mixed in optimum volumetric fractions that could lead to the maximum packing density based on model predictions. Powder bed packing density was measured on binary mixtures, ternary mixture, and each constituent powders. Furthermore, disk-shaped samples were made, using binder jetting additive manufacturing, from each constituent and mixed powder. Results show that binary and ternary mixtures have higher powder bed packing densities and sintered densities than the corresponding constituent powders. The disks made from the ternary mixture achieved the highest sintered density of 65.5%.

Wire + Arc Additive Manufacturing of Metals

2020 ◽  
pp. 106-126
Author(s):  
Krishna Kishore Mugada ◽  
Aravindan Sivanandam ◽  
Ravi Kumar Digavalli
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Manufacturing Sector ◽  
Manufacturing Processes ◽  
Deposition Rates ◽  
Direct Energy Deposition ◽  
Powder Bed ◽  
Direct Energy ◽  
Wire Arc Additive Manufacturing ◽  
Binder Jetting

Wire + Arc additive manufacturing (WAAM) processes have become popular because of their proven capabilities to produce large metallic components with high deposition rates (promoted by arc-based processes) compared to conventional additive manufacturing processes such as powder bed fusion, binder jetting, direct energy deposition, etc. The applications of WAAM processes were constantly increasing in the manufacturing sector, which necessitates an understanding of the process capability to various metals. This chapter outlines the significant outcomes of the WAAM process for most of the engineering metals in terms of microstructure and mechanical properties. Discussion on various defects associated with the processed components is also presented. Potential application of WAAM for different metals such as aluminum and its alloys, titanium, and steels was discussed. The research indicates that the components manufactured by the WAAM process have significant microstructural changes and improved mechanical properties.

scholarly journals An Automated Open-Source Approach for Debinding Simulation in Metal Extrusion Additive Manufacturing

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 2
Author(s):  
Tobias Rosnitschek ◽  
Johannes Glamsch ◽  
Christopher Lange ◽  
Bettina Alber-Laukant ◽  
Frank Rieg
Keyword(s):  
Additive Manufacturing ◽  
Open Source ◽  
Selection Process ◽  
Product Development Process ◽  
Element Analysis ◽  
Powder Bed ◽  
Optimal Orientation ◽  
Automated Simulation ◽  
Manufacturing Applications ◽  
Metal Extrusion

As an alternative to powder-bed based processes, metal parts can be additively manufactured by extrusion based additive manufacturing. In this process, a highly filled polymer filament is deposited and subsequently debindered and sintered. Choosing a proper orientation of the part that satisfies the requirements of the debinding and sintering processes is crucial for a successful manufacturing process. To determine the optimal orientation for debinding, first, the part must be scaled in order to compensate the sinter induced shrinkage. Then, a finite element analysis is performed to verify that the maximum stresses due to the dead load do not exceed the critical stress limits. To ease this selection process, an approach based on open source software is shown in this article to efficiently determine a part’s optimal orientation during debinding. This automates scaling, debinding simulation, and postprocessing for all six main directions. The presented automated simulation framework is examined on three application examples and provides plausible results in a technical context for all example parts, leading to more robust part designs and a reduction of experimental trial and error. Therefore, the presented framework is a useful tool in the product development process for metal extrusion additive manufacturing applications.

Binder Jetting Additive Manufacturing: Effect of Particle Size Distribution on Density

2021 ◽  
Vol 143 (9) ◽  
Author(s):  
Wenchao Du ◽  
Jorge Roa ◽  
Jaehee Hong ◽  
Yanwen Liu ◽  
Zhijian Pei ◽  
...  
Keyword(s):  
Particle Size ◽  
Packing Density ◽  
Density Ratio ◽  
Size Ratio ◽  
Powder Bed ◽  
Particle Size Ratio ◽  
Tap Density ◽  
Mixing Method ◽  
Component Particle ◽  
Binder Jetting

Abstract This paper reports a study on the effects of particle size distribution (tuned by mixing different-sized powders) on density of a densely packed powder, powder bed density, and sintered density in binder jetting additive manufacturing. An analytical model was used first to study the mixture packing density. Analytical results showed that multimodal (bimodal or trimodal) mixtures could achieve a higher packing density than their component powders and there existed an optimal mixing fraction to achieve the maximum mixture packing density. Both a lower component particle size ratio (fine to coarse) and a larger component packing density ratio (fine to coarse) led to a larger maximum mixture packing density. A threshold existed for the component packing density ratio, below which the mixing method was not effective for density improvement. Its relationship to the component particle size ratio was calculated and plotted. In addition, the dependence of the optimal mixing fraction and maximum mixture packing density on the component particle size ratio and component packing density ratio was calculated and plotted. These plots can be used as theoretical tools to select parameters for the mixing method. Experimental results of tap density were consistent with the above-mentioned analytical predictions. Also, experimental measurements showed that powders with multimodal particle size distributions achieved a higher tap density, powder bed density, and sintered density in most cases.

The Master Sinter Curve and Its Application to Binder Jetting Additive Manufacturing

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Evan Wheat ◽  
Gitanjali Shanbhag ◽  
Mihaela Vlasea
Keyword(s):  
Additive Manufacturing ◽  
Sintered Density ◽  
Prediction Errors ◽  
Heating Rates ◽  
Density Prediction ◽  
Axis Parallel ◽  
Apparent Activation Energies ◽  
Printing Direction ◽  
Binder Jetting ◽  
Cylindrical Samples

Abstract The master sinter curve (MSC) is an empirical model used to predict the density of a part after being sintered. The model is typically applied to components that undergo isotropic shrinkage. Parts manufactured using binder jetting additive manufacturing (BJAM) are known to have nonuniform powder systems and high levels of anisotropy. This work explores the application of the master sinter curve to components made by BJAM. Cylindrical samples were manufactured with the long axis parallel (vertical), perpendicular (horizontal), and 45 deg to the printing direction. A bimodal blend of titanium powder (0–45  µm and 106–150 µm) was used to make samples with consistent green densities (ranging from 47.2% to 52.3%) between the different orientations. Samples were then sintered at heating rates of 1, 3, and 5 °C/min to a maximum of 1400 °C. After sintering, the samples showed significant variation between the different orientations, with vertical samples on average 7.6 ± 2.98% and 4.7 ± 1.20% denser than the horizontal and the 45 deg samples, respectively. The calculated apparent activation energies for sintering were within the same range for all orientations, 200–260 kJ/mol for vertical and 45 deg, and 140–260 kJ/mol for horizontal samples. Validation sinter runs showed that the density prediction errors of the master sinter curves were between 0.9% and 4.3%. This work shows that the master sinter curve can be applied to predict the sintered density of components manufactured by binder jetting additive manufacturing.

Binder Jetting Additive Manufacturing of Metals: A Literature Review

2019 ◽  
Author(s):  
Ming Li ◽  
Wenchao Du ◽  
Alaa Elwany ◽  
Zhijian Pei ◽  
Chao Ma
Keyword(s):  
Additive Manufacturing ◽  
Dimensional Accuracy ◽  
Binding Agent ◽  
Metal Part ◽  
Spreading Process ◽  
Powder Bed ◽  
The Past ◽  
Wide Range ◽  
Binder Jetting ◽  
Two Parameter

Abstract Binder jetting, also known as 3D printing, is an additive manufacturing (AM) technology utilizing a liquid-based binding agent to selectively join the material in a powder bed. It is capable of manufacturing complex-shaped parts with a variety of materials. This paper provides an overview of binder jetting of metals with a discussion about the knowledge gaps and research opportunities. The review deals with two parameter categories in terms of the material and process and their impacts. The achieved density, dimensional accuracy, and mechanical strength are summarized and analyzed. Further in-depth consideration of densification is discussed corresponding to various attributes of the packing, printing, and sintering behaviors. Though binder jetting has attracted increasing attention in the past several years, this fabrication process is not well studied. The understanding of powder spreading process and binder-powder interaction is crucial to the development of binder jetting but insufficient. In addition, the lack of investigation on the mechanical behavior of binder jetting metal part restricts the actualization of its wide-range applications.

scholarly journals Fabrication of Single Crystals through a µ-Helix Grain Selection Process during Electron Beam Metal Additive Manufacturing

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 313 ◽  
Author(s):  
Martin R. Gotterbarm ◽  
Alexander M. Rausch ◽  
Carolin Körner
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Single Crystals ◽  
Electron Beam Melting ◽  
Selection Process ◽  
Powder Bed ◽  
Grain Structures ◽  
Selective Electron Beam Melting ◽  
Columnar Grain ◽  
Metal Additive

Selective Electron Beam Melting (SEBM) is a powder bed-based additive manufacturing process for metals. As the electron beam can be moved inertia-free by electromagnetic lenses, the solidification conditions can be deliberately adjusted within the process. This enables control over the local solidification conditions. SEBM typically leads to columnar grain structures. Based on numerical simulation, we demonstrated how technical single crystals develop in IN718 by forcing the temperature gradient along a µ-Helix. The slope of the µ-Helix, i.e., the deviation of the thermal gradient from the build direction, determined the effectiveness of grain selection right up to single crystals.

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