M.A. Jafari, W. Han, F. Mohammadi, A. Safari, S.C. Danforth and N. Langrana
In this article we present the system that we have developed at Rutgers University for the solid freeform fabrication of multiple ceramic actuators and sensors. With solid free…
Abstract
In this article we present the system that we have developed at Rutgers University for the solid freeform fabrication of multiple ceramic actuators and sensors. With solid free form fabrication, a part is built layer by layer, with each layer composed of roads of material forming the boundary and the interior of the layer. With our system, up to four different types of materials can be deposited in a given layer with any geometry. This system is intended for fabrication of functional parts; therefore the accuracy and precision of the fabrication process are of extreme importance.
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N. Venkataraman, S. Rangarajan, M.J. Matthewson, B. Harper, A. Safari, S.C. Danforth, G. Wu, N. Langrana, S. Guceri and A. Yardimci
Fused deposition of ceramics (FDC) is a solid freeform fabrication technique based on extrusion of highly loaded polymer systems. The process utilizes particle loaded…
Abstract
Fused deposition of ceramics (FDC) is a solid freeform fabrication technique based on extrusion of highly loaded polymer systems. The process utilizes particle loaded thermoplastic binder feedstock in the form of a filament. The filament acts as both the piston driving the extrusion and also the feedstock being deposited. Filaments can fail during FDC via buckling, when the extrusion pressure needed is higher than the critical buckling load that the filament can support. Compressive elastic modulus determines the load carrying ability of the filament and the viscosity determines the resistance to extrusion (or extrusion pressure). A methodology for characterizing the compressive mechanical properties of FDC filament feedstocks has been developed. It was found that feedstock materials with a ratio (E/ηa) greater than a critical value (3×105 to 5×105 s‐1) do not buckle during FDC while those with a ratio less than this range buckle.
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A. Bandyopadhyay, R.K. Panda, T.F. McNulty, F. Mohammadi, S.C. Danforth and A. Safari
Reviews the inherent advantages, i.e. design flexibility and processing, of manufacturing piezoelectric ceramics and composites with numerous architectures via rapid prototyping…
Abstract
Reviews the inherent advantages, i.e. design flexibility and processing, of manufacturing piezoelectric ceramics and composites with numerous architectures via rapid prototyping techniques. Reports on processing in which piezoelectric ceramics and composites with novel and conventional designs were fabricated using rapid prototyping techniques. Fused deposition of ceramics, fused deposition modeling, and Sanders prototyping techniques were used to fabricate lead‐zirconate‐titanate ceramics and ceramic/polymer composites via, first, direct fabrication and, second, indirect fabrication using either lost mold or soft tooling techniques.
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The United Nations (UN) actively incorporated new media as a tool for consultation and agenda setting during the Millennium Development Goal (MDG)–Sustainable Development Goal…
Abstract
The United Nations (UN) actively incorporated new media as a tool for consultation and agenda setting during the Millennium Development Goal (MDG)–Sustainable Development Goal (SDG) transition. As global actors shifted their attention to the sustainable development goals, the UN and its partners scaled up their digital engagement with civil society, multinational agencies, and country-level stakeholders to inform the post-2015 agenda. This chapter explored how the UN integrated Twitter into the post-2015 consultation and how the UN Women and the United Nations Girls’ Education Initiative used Twitter to construct and diffuse girls’ education policy discourse during the MDG–SDG transition.
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T.F. McNulty, F. Mohammadi, A. Bandyopadhyay, D.J. Shanefield, S.C. Danforth and A. Safari
A new family of thermoplastic binders has been developed for usage in fused deposition of ceramics (FDC). Mixtures were formulated consisting of a base binder, tackifier, wax, and…
Abstract
A new family of thermoplastic binders has been developed for usage in fused deposition of ceramics (FDC). Mixtures were formulated consisting of a base binder, tackifier, wax, and plasticizer. The resultant formulation was chosen based on mechanical, rheological, and thermal property requirements. A formulation consisting of 100 parts base binder (by weight), along with 20 parts tackifier, 15 parts wax, and five parts plasticizer exhibited an optimized compromise of mechanical, rheological, and thermal properties. This formulation was compounded with 55 vol. per cent lead zirconate titanate (PZT) powder, and extruded into filaments with a diameter of 1.75mm and a length of approximately 50 (+/‐10) cm. The resulting filaments were used to fabricate functional piezoelectric ceramic devices via FDC. The binder development process is described, along with the associated mechanical, rheological, and thermal property data.
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Mukesh K. Agarwala, Vikram R. Jamalabad, Noshir A. Langrana, Ahmad Safari, Philip J. Whalen and Stephen C. Danforth
Commercial solid freeform fabrication (SFF) systems, which have been developed for fabrication of wax and polymer parts for form and fit and secondary applications, such as moulds…
Abstract
Commercial solid freeform fabrication (SFF) systems, which have been developed for fabrication of wax and polymer parts for form and fit and secondary applications, such as moulds for casting, etc., require further improvements for use in direct processing of structural ceramic and metal parts. Defects, both surface as well as internal, are undesirable in SFF processed ceramic and metal parts for structural and functional applications. Process improvements are needed before any SFF technique can successfully be commercialized for structural ceramic and metal processing. Describes process improvements made in new SFF techniques, called fused deposition of ceramics (FDC) and metals (FDMet), for fabrication of structural and functional ceramic and metal parts. They are based on an existing SFF technique, fused deposition modelling (FDM) and use commercial FDM systems. The current state of SFF technology and commercial FDM systems results in parts with several surface and internal defects which, if not eliminated, severely limit the structural properties of ceramic and metal parts thus produced. Describes systematically, in detail, the nature of these defects and their origins. Discusses several novel strategies for elimination of most of these defects. Shows how some of these strategies have successfully been implemented to result in ceramic parts with structural properties comparable to those obtained in conventionally processed ceramics.
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Fulvio Lavecchia, Alessandro Pellegrini and Luigi Maria Galantucci
This paper aims to provide a comparison between the mechanical performance and microstructural aspects of stainless steel 17-4 PH processed using, respectively, two technologies…
Abstract
Purpose
This paper aims to provide a comparison between the mechanical performance and microstructural aspects of stainless steel 17-4 PH processed using, respectively, two technologies: atomic diffusion additive manufacturing (ADAM) and metal fused filament fabrication (MFFF).
Design/methodology/approach
Different tensile specimens have been printed using an industrial system and a consumer three-dimensional (3D) printer, varying two main 3D printing parameters. Mechanical and microstructural tests are executed to make a comparison between these two technologies and two different feedstock material, to identify the main differences.
Findings
These 3D printing processes make parts with different surface quality, mechanical and microstructural properties. The parts, printed by the industrial system (ADAM), showed lower values of roughness, respect those produced using the 3D consumer printer (MFFF). The different sintering process parameters and the two debinding methods (catalytic or solvent based) affect the parts properties such as porosity, microstructure, grain size and amount of δ-ferrite. These proprieties are responsible for dissimilar tensile strength and hardness values. With the aim to compare the performances among traditional metal additive technology, MFFF and ADAM, a basic analysis of times and costs has been done.
Originality/value
The application of two metal extrusion techniques could be an alternative to other metal additive manufacturing technologies based on laser or electron beam. The low cost and printing simplicity are the main drivers of the replacements of these technologies in not extreme application fields.
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Dan Qiu, Noshir A. Langrana, Stephen C. Danforth, Ahmad Safari and Mohsen Jafari
To fabricate high quality parts, and to make the development generic yet compatible with the in‐house hardware, a virtual simulation system has been developed, and an in‐house…
Abstract
To fabricate high quality parts, and to make the development generic yet compatible with the in‐house hardware, a virtual simulation system has been developed, and an in‐house intelligent multi‐material toolpath generation system has been under development. This new development includes the issues such as multiple fill‐toolpaths for the same material, interface mismatch between adjacent materials and the intelligent toolpath features for machine control. After the multi‐material toolpath file generated by the in‐house software, the existing virtual graphical simulation as well as well selected part fabrication experiments were used to validate it. Based on the authors’ ongoing research about multi‐material layered manufacturing, it was determined that the build characteristic was heavily dependent on the material being used. Therefore, it was important to develop the hardware/software that will accommodate this requirement.
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Tieshu Huang, Michael S. Mason, Xiyue Zhao, Gregory E. Hilmas and Ming C. Leu
The purpose of this paper is to develop an inexpensive and environmentally friendly solid freeform fabrication technique, called the freeze‐form extrusion fabrication (FEF), and…
Abstract
Purpose
The purpose of this paper is to develop an inexpensive and environmentally friendly solid freeform fabrication technique, called the freeze‐form extrusion fabrication (FEF), and use this technique in advanced ceramic fabrication.
Design/methodology/approach
FEF uses a highly loaded aqueous ceramic paste (≥50 vol.% solids loading) with a small quantity (∼2 vol.%) of organic binder to fabricate a ceramic green part layer by layer with a computer‐controlled 3D gantry machine at a temperature below the freezing point of the paste. Further, a freeze‐drying technique is used for preventing deformation and the formation of cracks during the green part drying process. Following the freeze‐drying, the ceramic green part undergoes binder removal and is sintered to near full density.
Findings
Extrudable, alumina pastes of high solids loading and process parameters for FEF processing of these pastes have been developed. Paste rheological properties and stability, extrusion rate, 3D gantry motion speed and other process parameters strongly affect the quality of the final ceramic parts. The minimum deposition angle, which reflects the maximum amount of extrusion offset to produce components with overhanging features without using support materials, is strongly related to the fabrication (environment) temperature. The lower the fabrication temperature, the lower the minimum deposition angle that could be achieved. Four point bending flexure strengths of the FEF processed Al2O3 test samples were 219 and 198 MPa for longitudinally deposited and transversely deposited samples, respectively. Major defects, which limited the strength of the materials, were due to under‐filling during the extrusion.
Originality/value
Successful development of the FEF technique will introduce a new approach to manufacturing ceramic materials into useful, complex shapes and components. The significant advantages of this technique include the use of environmentally friendly processing medium (water), inexpensive method of medium removal (freeze‐drying), and a much smaller quantity of organic binder to remove by pyrolysis techniques. The products can be sintered to near full density.
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Sunidhi Dayam, Puneet Tandon and Satwik Priyadarshi
This study aims to explore a technique of metal additive manufacturing (MAM) for producing parts in aluminium. The proposed technique mimics the process of metal injection…
Abstract
Purpose
This study aims to explore a technique of metal additive manufacturing (MAM) for producing parts in aluminium. The proposed technique mimics the process of metal injection moulding but with the tools meant for fused freeform fabrication machines.
Design/methodology/approach
The work focusses on the preparation of novel feedstock by mixing the aluminium powder with binders made from different compositions of high-density polyethylene, paraffin wax, petroleum jelly and stearic acid. Further, a novel experimental setup with a paste extruder was designed to print the test samples. A sintering cycle was developed in-house along with a thermal debinding procedure. An experimental campaign was also carried with the proposed technique to establish a proof-of-concept. Produced samples were tested for part density, hardness, compressive strength and tensile strength.
Findings
The results indicate geometrical accuracy was an issue owing to the presence of petroleum jelly in the binder-powder mixture. Therefore, machining as a post-processing operation seems to be unavoidable. The study also elucidates that the printed specimen may require further heat treatment to replace wrought alloys. However, the sintered parts show hardness and compressive strength similar to that of wrought aluminium alloy.
Originality/value
The novelty of the work is to develop the cost effective and scalable powder extrusion-based MAM process for printing the aluminium parts.