Search Results (108)

This paper catalogues a series of experiments we conducted to explore how to 3D print a DC electric motor. The individual parts of the electric motor were 3D printed but assembled by hand. First, we focused on a rotor with soft magnetic properties, for which we adopted ProtoPasta^TM, which is a commercial off-the-shelf PLA filament incorporating iron particles. Second, we focused on the stator permanent magnets, which were 3D printed through binder jetting. Third, we focused on the wire coils, for which we adopted a form of laminated object manufacture of copper wire. The chief challenge was in 3D printing the coils, because the winding density is crucial to the performance of the motor. We have demonstrated that DC electric motors can be 3D printed and assembled into a functional system. Although the performance was poor due to the wiring problem, we showed that the other 3D printing processes were consistent with high performance. Nevertheless, we demonstrated the principle of 3D printing electric motors. Full article

The textile industry is progressively shifting towards more sustainable solutions, particularly in the field of printing technologies. This study reports the development and evaluation of water-based pigment inks formulated with bio-based pigments derived from intermediates produced via bacterial fermentation. Two pigments—indigo (blue) and quinacridone (red)—were incorporated into ink formulations and applied on cotton and polyester fabrics through valve-jet inkjet printing (ChromoJet). The physical properties of the inks were analyzed to ensure compatibility with the equipment, and printed fabrics were assessed as to their color fastness to washing, rubbing, artificial weathering, and artificial light. The results highlight the good performance of the bio-based inks, with excellent light and weathering fastness and satisfactory wash and rub resistance. The effect of different pre-treatments, including a biopolymer and a synthetic binder, was also investigated. Notably, the biopolymer pre-treatment enhanced pigment fixation on cotton, while the synthetic binder improved wash fastness on polyester. These findings support the integration of biotechnologically sourced pigments into eco-friendly textile digital printing workflows. Full article

The escalating heat flux densities in high-performance electronics necessitate superior thermal management. This study enhanced pool-boiling heat transfer, a method offering high heat removal capacity, by leveraging Binder Jetting 3D Printing (BJ3DP) to create complex porous copper structures without the need for chemical treatments. This approach enables a reliable utilization of phenomena like capillarity for improved performance. Three types of porous copper structures, namely Large Lattice, Small Lattice, and Staggered, were fabricated on pure copper substrates and tested via pool boiling of de-ionized and de-gassed water at atmospheric pressure. Compared to a plain polished copper surface, which exhibited a critical heat flux (CHF) of 782 kW/m² at a wall superheat of 18 K, the 3D-printed porous copper surfaces showed significantly improved heat transfer performance. The Staggered surface achieved a conventional CHF of 2342.4 kW/m² (a 199.7% enhancement) at a wall superheat of 24.6 K. Notably, the Large Lattice and Small Lattice structures demonstrated exceptionally stable boiling without reaching the typical catastrophic CHF within the experimental parameters. These geometries continued to increase in heat flux, reaching maximums of 2397.7 kW/m² (206.8% higher at a wall superheat of 55.6 K) and 2577.2 kW/m² (229.7% higher at a wall superheat of 39.5 K), respectively. Subsequently, a gradual decline in heat flux was observed with an increasing wall superheat, demonstrating an outstanding resistance to the boiling crisis. These improvements are attributed to the formation of distinct vapor–liquid pathways within the porous structures, which promotes the efficient rewetting of the heated surface through capillary action. This mechanism supports a highly efficient, self-sustaining boiling configuration, emphasizing the superior rewetting and vapor management capabilities of these 3D-printed porous structures, which extend the boundaries of sustained high heat flux performance. The porous surfaces also demonstrated a higher heat transfer coefficient (HTC), particularly at lower heat fluxes (≤750 kW/m²). High-speed digital camera visualization provided further insight into the boiling phenomenon. Overall, the findings demonstrate that these BJ3DP structured surfaces produce optimized vapor–liquid pathways and capillary-enhanced rewetting, offering significantly superior heat transfer performance compared to smooth surfaces and highlighting their potential for advanced thermal management. Full article

This paper reports on a preliminary experimental study on binder jetting 3D printing of biomass–fungi composite materials. Biomass–fungi composite materials have potential applications in the packaging, furniture, and construction industries. Biomass particles (prepared from agricultural residues) act as the substrate of the composite materials. The filamentous roots of fungi intertwine and bind biomass particles together. In this study, the biomass (hemp hurd) powders used had two distinct average particle sizes. The liquid binder used contained fungi (Trametes versicolor) cells. T-shaped samples were printed using a lab-designed binder jetting setup. Printed samples were kept inside an incubator oven for four days to allow fungi to grow. Afterward, loose biomass powder was removed from the T-shaped samples. The samples were then kept inside the incubator oven for eight more days to allow further fungal growth. The samples were subsequently placed in an oven at 120 °C for four hours to terminate all fungal activity in the samples. SEM micrographs were taken of the cross-sectional surfaces of the samples. The micrographs showed a significant presence of fungi hyphae inside the printed samples, providing evidence of the binding of biomass particles by the hyphae. Full article

This study investigates the fabrication and bioactivity of monophasic octacalcium phosphate (OCP) constructs using 3D-printed calcium sulfate precursors. A single-step and a two-step process were employed, transforming calcium sulfate into OCP through a controlled phase transformation in a disodium hydrogen phosphate solution. The results revealed that a single-step process for OCP conversion in 3D printed samples was unsuccessful due to incomplete transformation and the formation of intermediate phases such as brushite and monetite. In contrast, the two-step process enabled the efficient production of monophasic OCP in a shorter timeframe. The converted OCP samples exhibited a compressive strength of 7.65 ± 0.46 MPa and a contact angle of zero, indicating adequate handling strength and high wettability. The resorbability of 3D-printed OCP in simulated body fluid (SBF) was evaluated, showing weight loss through gradual dissolution accompanied by the release of calcium and phosphorus ions, followed by the consumption of these ions for reprecipitation back into OCP without direct transformation into hydroxyapatite (HA). Biocompatibility and bioactivity testing demonstrated high cell viability (96.67 ± 0.18%) using the MTT assay, indicating that the 3D-printed OCP was not cytotoxic. Alamar blue and alkaline phosphatase (ALP) activity assay showed that 3D-printed OCP supported preosteoblast proliferation and osteogenic differentiation. Full article

Silicon carbide (SiC) materials have demonstrated promising application prospects in modern manufacturing due to their outstanding physical and chemical properties. With its process flexibility and formation feasibility, binder jetting 3D printing technology has become a crucial technical approach to meet the demand for mass production of complex, high-performance SiC components. Addressing the technical challenges of traditional manufacturing techniques in achieving high-quality, complex-shaped SiC components, this paper systematically reviews the application of binder jetting 3D printing technology in fabricating high-quality SiC-based ceramic components, with a particular focus on the regulation of key process parameters affecting SiC green body formation quality and the optimization of post-densification processes. Firstly, this paper elaborates on the powder pretreatment, green part formation process, and post-processing chain involved in this technology, establishes an evaluation index system for formation quality, and provides research directions for rapid prototyping of SiC powders. Secondly, it provides an in-depth analysis of the influence patterns of jetting parameters (e.g., jetting conditions, powder characteristics, binder properties) and various post-processing techniques on the quality of SiC-based components, along with optimization methods to enhance the dimensional accuracy and mechanical properties of 3D-printed SiC components. Furthermore, this paper systematically summarizes advanced characterization methods for evaluating formation quality and demonstrates the technology’s application potential across multiple industrial fields through representative engineering cases. Finally, it predicts the future development trends of this technology and discusses potential application expansion directions and key scientific issues in current research, aiming to provide theoretical references for promoting in-depth development of this technology. Full article

Binder jetting additive manufacturing (BJAM) of silicon carbide (SiC) has been reported in the literature. In the reported studies, the effects of the compaction thickness on the properties of SiC green parts printed by BJAM have largely been unexamined. This study aims to fill this gap in the literature by investigating the effects of the compaction thickness on the density, integrity, and microstructure of SiC green parts printed by BJAM. In this study, experiments were conducted using four levels of compaction thickness at two levels of layer thickness. The results indicate that increasing the compaction thickness enhances the green part density, reaching 1.85 g/cm³ at a layer thickness of 45 µm and 1.87 g/cm³ at a layer thickness of 60 µm, respectively. However, a higher compaction thickness might also introduce defects in green parts, such as cracks. Scanning electron microscopy (SEM) analysis confirmed the improved particle packing and reduced porosity with the increased compaction thickness. These findings underscore a trade-off between density and defect formation, providing critical insights for optimizing BJAM process variables for fabricating SiC parts. Full article

The binder jetting additive manufacturing process offers the ability to create three-dimensional parts layer by layer. However, using any powder that contains particles with different sizes, shapes, or densities can lead to powder segregation during the mixing, dispensing, and spreading steps of the binder jetting additive manufacturing process. Powder segregation can often lead to uneven powder distribution across the powder bed, potentially causing defects in final parts. Therefore, it is important to understand powder segregation in mixing, dispensing, and spreading. Reported studies on powder segregation in mixing were conducted primarily on pharmaceutical or food powder that have different properties compared to metal or ceramic powder used in binder jetting additive manufacturing. There is a need for a deep understanding of how mixing speed and mixing time affect powder segregation in the context of binder jetting additive manufacturing. This paper reports an experimental investigation using a two-variable, two-level full-factorial design to examine the main effects and interaction effect of mixing speed and mixing time on powder segregation in the mixing of Powder A and Powder B for binder jetting additive manufacturing. The results reveal that segregation was more severe at the high level of mixing speed and the high level of mixing time. These findings provide useful insights for selecting mixing variables and controlling segregation, essential for achieving high-quality printed parts in binder jetting additive manufacturing. Full article

Binder jetting is the most widely implemented additive technology for the fabrication of sand molds. However, the use of furan binder-jetting technology in the production of molds for vacuum casting is hindered by the thermal destruction of the furan binder accompanied by violent gas emission that occurs during the mold heating process. This investigation explores the potential of using the molds obtained via furan binder jetting 3D printing and further impregnation in colloidal silica binder and sintering. Two distinct sands, proppant and cenosphere, were utilized in the fabrication of the mold components exhibiting different thermal properties. An examination of the structure of the initial sands and samples produced via different impregnation and sintering regimes was conducted via scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffractometry, thermogravimetric analysis, and micro computed tomography. Furthermore, the bending mechanical properties and linear shrinkage of the samples were determined. The experimental findings demonstrated that the specific impregnation and sintering regimes examined in this study yielded sufficient mechanical properties for the casting molds and the structure with cristobalite bridges. The mold assembly, composed of proppant and cenosphere sands-based parts, was produced, and impeller nickel-based superalloy castings were fabricated. The findings of this study demonstrate that the utilization of a furan binder-jetting technique, in conjunction with impregnation in colloidal silica binder, is a promising technology for the manufacture of high-melting-temperature alloy casting. Full article

The objective of this study is to demonstrate the feasibility of producing SiC–aluminum composites by the binder jetting 3D printing of SiC preforms and spontaneous infiltration by aluminum. SiC preforms fabricated using binder jetting 3D printing were subjected to several post-processing steps (including curing, depowdering, debinding, and sintering). Sintering was conducted at 1700 °C, and aluminum infiltrating was conducted at 1000 °C, with both carried out in a controlled nitrogen environment under a pressure of 25 psi. The bulk density of the sintered SiC preforms was increased by 14% after infiltration. X-ray diffraction and energy-dispersive X-ray spectroscopy confirmed the presence of aluminum in the SiC matrix. This paper is the first to report fabricating SiC–aluminum composites by binder jetting and infiltrating, providing a new approach to producing these composites with potential applications in the aerospace and automotive industries. Full article

This study investigates the development and application of climate friendly processes in the foundry industry, particularly with regard to the use of inorganic binders to reduce emissions and pollution. An inorganic binder system based on water glass, which is used in 3D printing technology for the production of sand molds and core, is being tested and the possibility of determining a kinetic model for the curing kinetics of sodium silicate as an inorganic binder is investigated. The aim is to use a kinetic model to better describe the microwave process currently required in binder jetting for drying the binder and catalyzing the chemical reaction of the binder during curing. For sodium silicate in particular, there is still no scientific knowledge available in this respect, which is why basic investigations based on thermogravimetry or heat flow difference calorimetry must first be carried out. In this way, it should be possible to simulate the drying process in the microwave, which has so far been based on empirical values, in order to maximize the efficiency of this process and also the quality of the components. The results indicate that the weight loss and weight changes depend on the heating rates and that a heating rate of 30 K/min is not sufficient to fully cure the sample at 500 °C. The thermogravimetric analysis (TGA) shows that the fastest weight loss occurs at the beginning of the measurement, indicating a partial pre-curing of the sample before the measurement. From the measurements, an average activation energy of 144.18 kJ/mol could be determined using the Friedman method and 123.36 kJ/mol and 123.31 kJ/mol using the Ozawa–Flynn–Wall and Kissinger–Akahira–Sunose methods, respectively. Measurements of the heat flow at a heating rate of 30 K/min indicate partially exothermic reactions during the curing process. Full article

Cemented carbides, renowned for their exceptional strength, hardness, elastic modulus, wear resistance, corrosion resistance, low coefficient of thermal expansion, and chemical stability, have long been indispensable tooling materials in metal cutting, oil drilling, and engineering excavation. The advent of additive manufacturing (AM), commonly known as “3D printing”, has sparked considerable interest in the processing of cemented carbides. Among the various AM techniques, Selective Laser Melting (SLM), Selective Laser Sintering (SLS), Selective Electron Beam Melting (SEBM), and Binder Jetting Additive Manufacturing (BJAM) have garnered frequent attention. Despite the great application potential of AM, no single AM technique has been universally adopted for the large-scale production of cemented carbides yet. The SLM and SEBM processes confront substantial challenges, such as a non-uniform sintering temperature field, which often result in uneven sintering and frequent post-solidification cracking. SLS notably struggles with achieving a high relative density of carbides. While BJAM yields WC-Co samples with a lower incidence of cracking, it is not without flaws, including abnormal WC grain growth, coarse WC clustering, Co-rich pool formation, and porosity. Three-dimensional gel-printing, though possessing certain advantages from its sintering performance, falls short in dimensional and geometric precision control, as well as fabrication efficiency. Cemented carbides produced via AM processes have yet to match the quality of their traditionally prepared counterparts. To date, the specific densification and microstructure evolution mechanisms during the AM process, and their interrelationship with the feedstock carbide material design, printing/sintering process, and resulting mechanical behavior, have not been thoroughly investigated. This gap in our knowledge impedes the rapid advancement of AM for carbide processing. This article offers a succinct overview of additive manufacturing of cemented carbides, complemented by an analysis of the current research landscape. It highlights the benefits and inherent challenges of these techniques, aiming to provide clarity on the present state of the AM processing of cemented carbides and to offer insights into potential future research directions and technological advancements. Full article

Stainless steel 17-4PH is valued for its high strength and corrosion resistance but poses machining challenges due to rapid tool wear. This research investigates the use of pulsed electron beam surface treatment to enhance the surface properties of components fabricated by binder jetting additive manufacturing. The aim is to improve the tribological performance compared to the as-sintered condition and the H900 aging process, which optimizes hardness and wear resistance. Printed samples were sintered in a reducing atmosphere and superficially treated with an electron beam by varying the voltage and the pulse count. Results showed that the voltage affects the roughness and thickness of the treated layer, while the number of pulses influences the hardening of the microstructure and, consequently, the wear resistance. A reciprocating linear pin-on-disk wear test was conducted at 2 N and 10 Hz. Surface-treated samples exhibited lower coefficients of friction, though the values approached those of aged samples after the abrasion of the melted layer, indicating a deeper heat-affected zone formation. Still, the friction remained lower than that of as-printed specimens. This study demonstrates that optimizing electron beam parameters is vital for achieving surface performance comparable to bulk aging treatments, with significant implications for long-term wear resistance. Full article

Metal Binder Jetting (BJT/M) has emerged as a promising additive manufacturing (AM) technology for the realization of complex parts using a wide range of metal alloys. This technology offers several advantages, such as design flexibility, reduced lead times, a high building rate, and the ability to fabricate intricate geometries that are difficult or impossible to achieve with conventional manufacturing methods. Cobalt Chromium Molybdenum (CoCrMo) alloys are particularly suitable for demanding applications in the aerospace, biomedical, and industrial sectors that require high strength and hardness, corrosion resistance, and biocompatibility. In this work, ten cubic and ten tensile samples were printed with a layer height of 50 µm using the shell printing method, debound and sintered at 1325 °C for 4 h, with the aim of investigating the properties of CoCrMo parts made using BJT technology. A density of 7.88 g/cc was obtained from the Archimede’s test. According to the printing and sintering parameters, an average hardness of 18.5 ± 1.8 HRC and an ultimate tensile strength of 520.5 ± 44.6 MPa were obtained. Finally, through a microstructure analysis, an average grain size of 182 ± 14.7 µm was measured and the presence of an intergranular Cr-rich phase and Mo-rich carbides was detected. Full article

Binder Jetting (BJT), a powder-based additive manufacturing technology, has been shown to be a fast and reproducible green shaping process for many different metals. Due to its high productivity and versatility in material processing, BJT is gaining increasing importance in the manufacturing sector. It can also be used for the production of WC-Co hardmetals, a primary ceramic-based composite often used for tools and wear parts. Five different BJT printers from four different manufacturers were evaluated to assess their effectiveness and feasibility in producing hardmetals based on the same WC-12 wt.% Co starting powders. The analysis focused on comparing the properties of the resulting hardmetals, as well as evaluating the printing performance. The results show that all tested BJT printers are fundamentally well suited for producing green hardmetal parts, which can achieve full density after sintering. This work highlights the potential of BJT technology in hardmetal manufacturing for tool production. Full article