Search results

This work is focused on the realization of copper parts using the material extrusion additive manufacturing debinding and sintering (MEX+D&S) technology.

A highly filled filament with 90 Wt.% of copper is used to realize nine different combinations varying the printing speed and the flow rate. The following thermal debinding and sintering are performed at 483 °C and 1057 °C, respectively, burying the samples in specific refractory powder and carbon. The green and sintered density are measured and an inspection at optical microscope is implemented for a detailed internal analysis of the defects.

The samples, that reported the highest values of the green density, become the worst in the sintered condition due to evident swelling defect generated by the entrapped polymer during the thermal debinding. On the other hand, the parts with the lower values of green density allowed to achieve a satisfying density value without significant external defects.

The realization of copper parts through laser-based additive manufacturing technologies shows several troubles related to the rapid heat transfer and the high reflectivity of copper, which is a hinder of the absorption of the laser power. The MEX+D&S becomes an easier and economical alternative for the realization of copper parts. The internal inspection of the samples revealed the need for the improvement on the process chain, adopting a different debinding process to open channels during the thermal debinding to avoid the entrapment of the polymer.

The purpose of this study is to investigate the effect of two unique processing routes (solvent jetting (SJ) and binder jetting (BJ)), on the green density of printed stainless steel 316L (SS316L) and Nickel (Ni) powders.

In the SJ processing route, a solvent is jetted unto the powder/binder mixture to selectively activate the binder, layer by layer. In the BJ processing route, a solution of the binder mixture is jetted onto the powder bed to selectively bind powder particles. The effects of printing parameters such as layer height, roller speed, shaker speed and nozzle temperature on the green density of printed components are investigated and compared for both processing routes.

Results show that layer height and nozzle temperature affect the relative density of the printed compact for both processing routes. Slightly higher relative densities were achieved via the SJ route, with the overall highest relative density being 42.7% at 100 µm layer height and 70% nozzle temperature for the SS316L components and 43.7% at 150 µm layer height and 90% nozzle temperature for the Ni components, respectively. Results also show an increase in the final sintered relative density with an increase in green (printed) relative density of the solvent jetted SS316L components, with the highest relative density being 87.2%.

The paper studies the influence of printing parameters on the green density of printed SS316L and Ni samples in an unprecedented effort to provide a comparative understanding of the process-property relationships in BJ and SJ of SS316L and Ni components to the additive manufacturing research community.

This study aims at compensating for sintering deformation of components manufactured by metal binder jetting (MBJ) technology.

In the present research, numerical simulations are used to predict sintering deformation. Subsequently, an algorithm is developed to counteract the deformations, and the compensated deformations are morphed into a CAD model for printing. Several test cases are designed, compensated and manufactured to evaluate the accuracy of the compensation calculations. A consistent accuracy measurement method is developed for both green and sintered parts. The final sintered parts are compared with the desired final shape, and the accuracy of the model is discussed. Furthermore, the effect of initial assumptions in the calculations, including green part densities, and green part dimensions on the final dimensional accuracy are studied.

The proposed computational framework can compensate for the sintering deformations with acceptable accuracy, especially in the directions, for which the used material model has been calibrated. The precise assumption of green part density values is important for the accuracy of compensation calculations. For achieving tighter dimensional accuracy, green part dimensions should be incorporated into the computational framework.

Several studies have already predicted sintering deformations using numerical methods for MBJ parts. However, very little research has been dedicated to the compensation of sintering deformations with numerical simulations, and to the best of the best of the authors' knowledge, no previous work has studied the effect of green part properties on dimensional accuracy of compensation calculations. This paper introduces a method to omit or minimize the trial-and-error experiments and leads to the manufacturing of dimensionally accurate geometries.

Libraries have a variety of computer printers, faxes, network printers and photocopiers. All these machines have an environmental impact using paper, ink and electricity. This paper aims to discuss strategies for lessening the impact of these devices.

The paper provides a “how‐to” approach for librarians to achieve greener printing and copying.

Modification in library procedures can result in greener printing and copying.

The paper reviews the research on greener printing and provides practical suggestions for achieving greener printing and copying.

The purpose of this paper is to describe the implementation of a print management system to control costs and reduce waste associated with printing practices.

A paper collection study found that 8 percent of pages printed in the library were never claimed. A print management system was implemented requiring print jobs to be manually released by users. Statistics on toner lifespan and number of pages printed before and after the system was implemented were compared.

The print management system reduced the total number of pages printed in a semester by 32 percent from Fall 2009 to Fall 2011 and increased the lifespan of toner cartridges so they would perform more efficiently.

Implementing a print management system without charging students a printing fee reduces the amount of wasted paper and the costs associated with purchasing paper and toner for printing services.

The paper describes the implementation of a print management system in a library that has substantially reduced the number of pages printed from library computers and the amount of toner used. The authors believe they have made a significant impact on reducing a primary area of waste.

This study aims to investigate the performance of filament-based material extrusion additive manufacturing (MEX), combined with debinding and sintering, as a novel approach to manufacturing ceramic components.

A commercial ZrO₂ filament was selected and analysed by infra-red (IR) spectroscopy, rheology and thermo-gravimetry. The influence of the print parameters (layer thickness, flow rate multiplier, printing speed) and sintering cycle were investigated to define a suitable printing and sintering strategy. Biaxial flexure tests were applied on sintered discs realised with optimised printing strategies, and the results were analysed via Weibull statistics to evaluate the mechanical properties of printed components. The hardness and thermal conductivity of sintered components were also tested.

Layer thickness and flow rate multiplier of the printing process were proved to have significant effect on the density of as-printed parts. Optimised samples display a sintered density >99% of the theoretical density, 20% linear sintering shrinkage, a characteristic flexural strength of 871 MPa with a Weibull modulus of 4.9, a Vickers hardness of 12.90 ± 0.3 GPa and a thermal conductivity of 3.62 W/mK. Gyroids were printed for demonstration purposes.

To the best of the authors’ knowledge, this work is the first to apply biaxial flexure tests and Weibull statistics to additively manufactured MEX zirconia components, hence providing comparable results to other additive technologies. Moreover, fractography analysis builds the connection between printing defects and the fracture mechanism of bending. This study also provides guidelines for fabricating high-density zirconia components with MEX.

With a growing list of available materials and processes, the inherent mechanical and thermophysical properties of three-dimensional (3D) prints are important design targets. This paper aims to study the functionality of binder jet 3D printed objects for thermally activated building construction elements and recyclable formwork for concrete structures.

Binder jet printed sand samples with various material and post-processing parameters (infiltration and baking) are prepared and studied. Using a statistical experiment design, the mechanical (flexural and compressive strength) and thermal (conductivity and specific capacity) characteristics are quantified.

Relative to the unprocessed “green” print samples, post-processing improved the flexural and compressive strength of the samples by factors of 6.9 and 21.6, respectively; the thermal conductivity and specific heat capacity were improved by factors of 7.7 and 1.2, respectively. For the investigated temperature range (20°C–200°C), the “green” prints showed excellent stability while the stability of post-processed samples depended on the infiltrate used. Microscopic images of the microstructures offered evidence to support improvement in the mechanical and thermo-physical characteristics of the 3D printed sand elements.

The literature review concluded that optimal printing parameters and infiltration under vacuum could further improve the mechanical and thermo-physical properties of the binder jet printed elements. However, both these factors were not explored in this research. The statistical experimental design approach provided more flexibility to choose the number of experiments for a fixed amount of time and resources. However, for future work, a more extensive number of experiments and reproducibility testing for each combination of binder-infiltrate is recommended.

3D printing has been identified as a promising opportunity to reduce material usage and improve construction efficiency in the field of architecture and building engineering. The emerging fabrication technologies are further expected to significantly reduce the operational energy of buildings through performance integration, i.e. multi-functional building elements with integrated heat- and mass-transfer capabilities to replace conventional systems.

This study has quantified the impact of infiltration on the mechanical and thermo-physical characteristics of sand-printed elements and, as such, reports reproducible functional performance maps for sand-print applications. The research demonstrates a way to achieve the desired functional characteristics of 3D prints through combinations of material selection and process/post-processing parameters.

The purpose of this paper is to explore the use of binder jetting to fabricate high-purity copper parts. The ability to fabricate geometrically complex copper shapes would have implications on the design and manufacture of components for thermal management systems and structural electronics.

To explore the feasibility of processing copper via binder jetting, the authors followed an established material development process that encompasses powder selection and tuning process parameters in printing and thermal cycles. Specifically, the authors varied powder size and sintering cycles to explore their effects on densification.

Three differently sized copper powders were successfully printed, followed by sintering in a reducing atmosphere. It was found that a 15-μm-diameter powder with a sintering cycle featuring a 1,080°C maximum temperature provides the most dense (85 per cent) and pure (97 per cent) final copper parts of the parameters tested.

Due to powder-based additive manufacturing techniques’ inherent limitations in powder packing and particle size diameter, there are difficulties in creating fully dense copper parts. To improve thermal, electrical and mechanical properties, future work will focus on improving densification.

The paper demonstrates the first use of binder jetting to fabricate copper artifacts. The resulting copper parts are denser than what is typically found in binder jetting of metal powders (without infiltration); significant opportunity remains to further optimize the manufacturing process by introducing novel techniques to tailor the material properties for thermal/electrical applications.

The surface energy of the printing material can be increased to desired levels with different chemicals or methods. However, the important thing is that the surface properties of printing material are not affected negatively. In this way the aim of this paper provide that the surface properties of matte and glossy coated paper is improved by the argon containing atmospheric pressure plasma device because the plasma treatment method does not occur surface damaging on the papers.

In experimental studies, test samples cut from 160 mm × 30 mm in size from 115 g/m² gloss- and matt-coated papers were used. The plasma treatments of paper samples were carried out with an argon containing atmospheric pressure plasma device of laboratory scale that produces plasma of the corona discharge type at radio frequency. The optimized plasma parameters were at a frequency of 20 kHz and plasma power 200 W. A copper electrode of length 12 cm and diameter 2.5 mm was placed in the centre of the nozzle.

Research findings showed that the surface energies of the papers increased with the increase in plasma application time. While the contact angle of the untreated glossy paper is 82.2, 8 second plasma applied G3 sample showed 54 contact angle value. Similarly, the contact angle of the base paper of matt coated is 91.1, while M3 is reduced to 60.4 contact angles by the increasing plasma time.

Plasma treatment has shown that no chemical coating is needed to increase the wettability of the paper surface by reducing the contact angle between the paper and the water droplet. In addition, the surface energies of all papers treated by argon gas containing atmospheric pressure plasma, increased. Plasma treatment provides to improve both the wettability of the paper and the adhesion property required for the ink, with an environmentally friendly approach.

This study aims to experimentally investigate the effect of the powder material characteristics on the qualities of the binder jetting additive manufacturing parts both before and after post processing (sintering).

Three different types of the 316L stainless steel powder feedstock with various mean particle sizes and size distributions were studied. The influence of the powder particle size distributions and pore sizes on the powder bed packing densities and on the dynamics of the binder droplet-powder bed interactions were characterized. In addition, the surface roughness and densities of these parts both in the green state and after sintering were studied.

The results revealed the significant role of the powder feedstock characteristics on the liquid binder/powder bed interaction and consequently on the dimensional accuracies of the green parts. It was observed that the parts printed with the smaller mean particle sizes resulted in better surface finish and higher final densities after sintering. Furthermore, the hardness of the sintered parts produced with smaller powder particles exhibited higher values compared to the parts fabricated with the larger particles. On the other hand, larger particle sizes are advantageous for various green part qualities including the dimensional accuracies, green part densities and surface roughness.

This study establishes more comprehensive correlations between the powder feedstock characteristics and various quality criteria of the printed binder jetting components in both green and sintered states. These correlation are of critical importance in choosing the optimal process parameters for a given material system.