Flexible Manufacturing Method Research Articles

Integrated manufacturing method of multimaterial sand mold by binder jetting

Purpose This paper aims to develop a flexible manufacturing method for multimaterial sand molds to realize efficient additive manufacturing of multimaterial sand molds. Design/methodology/approach To study the influence of multimaterial sand laying process parameters on the quality of powder bed and optimize the design of multimaterial sand laying device. Numerical simulation and X-ray Computed Tomography are used to study the penetration behavior and curing morphology of resin in different sand particles. Findings The surface roughness and porosity of the multimaterial powder bed that meet the requirements of sand-based additive manufacturing can be obtained under the optimal printing process, that is, the sanding speed of 140.0 mm/s and sanding roller diameter of 15.0 mm. The resin penetration process of the multimaterial sand molds shows a pattern of transverse expansion and longitudinal penetration. In terms of the resin curing morphology, the maximum thickness of the resin film layer of zircon sand reaches 30.5 ± 1.0 µm, which has the best tensile property, followed by silica sand and the thinnest resin film layer of chromite sand. Originality/value In this work, a highly flexible integrated combined sand-laying device suitable for multimaterial sand-laying tests is developed, which can obtain a multimaterial powder bed that meets the needs of sand additive manufacturing. Subsequent casting print tests also verify that the program can meet the needs of multimaterial sand mold additive manufacturing.

Manufacturing of hexagonal cross-section thermoplastic matrix composite parts with automatic filament winding system

Thermoplastic filament winding is a flexible manufacturing method typically used in the production of cylindrical composite structures, allowing for in-situ consolidation without the need for a second consolidation step. The objective of this study is to produce non-cylindrical geometries, typically manufactured using thermoset matrix composites according to the literature, using the thermoplastic filament winding process. For this purpose, glass fiber (GF) reinforced polypropylene (PP) prepreg tapes were used to produce hexagonal cross-section thermoplastic composite parts. The critical process parameters; hot-air heater nozzle temperature, compression roller pressure, the linear speed of mandrel rotation, and corner radius of the mandrel, were determined using the Taguchi experimental design method. The interlaminar shear strength (ILSS) and maximum compressive strength (σmax) values were obtained as 211 MPa and 49.40 MPa as maximum, respectively. ANOVA analysis showed that the corner radius had the most significant impact on ILSS, while mandrel rotation speed and temperature were critical for σmax.

(Invited) Engineering of Nanostructured Aluminum-Based and Polymer-Based Platforms for SERS Sensing

There has been great hope for ultrasensitive detection methods with the application of Surface Enhanced Raman Spectroscopy (SERS) because of its impressive advancements. Nevertheless, a major challenge is the creation of large-scale, controllable, and reproducible substrates with high SERS activity [1]. As a basis for SERS detection, we report here the fabrication of different types of aluminum-based and polymer-based SERS platforms with the synthesis of gold nanoparticle (AuNP) arrays on them. The tunability of the AuNPs size and distribution is achieved by methodically controlling the aluminum substrates nanostructuration and the subsequent processes for the synthesis of the AuNP. This research presents a scalable and dependable approach for creating ordered Au patterns on nanostructured aluminum and polymer substrates.For both aluminum-based and polymer-based platforms, the initial formation of nanoporous anodic alumina (NAA) on an aluminum substrate by electrochemical anodization [2] is essential. The electrolytes used (sulphuric, oxalic, or phosphoric acid) and its respective concentration determines the ideal voltage for anodization and the electrolyte temperature [3,4]. The formed NAA layer is chemically removed obtaining a nanostructured aluminum substrate with a hexagonally ordered distribution of nanoconcavities [5,6]. The distance between nanocavities ranges from tens to hundreds of nanometers depending on the electrolyte used [7]. The polymer-based nanostructured substrates are formed with the deposition of the selected polymer on the obtained aluminum nanoconcavities substrates and peeled off when dried. Instead of nanoconcavities, it presents a distribution of nanosemispheres that corresponds to the imprinting of the aluminum nanoconcavities on the polymer.The final SERS platforms are obtained with the gold sputtering on the nanoconcavities aluminum substrates and the polymer substrates, followed by a thermal annealing process [8]. The result is a scalable, ordered and controlled distribution of AuNPs on the nanostructured substrates (Fig. 1). An evaluation of the sputtering time and the thermal annealing paramenters (time and temperature) is presented. Over a large surface area of several square centimeters, the AuNPs size, shape, and interparticle spacing may be controlled by using the flexible manufacturing method discussed in this work.All these AuNPs nanostructured platforms have shown high and interesting amplifications of the Raman signal demonstrating its suitability for SERS detection of several molecules like 4-Mercaptopyridine, rhodamine, streptavidine, melamine, etc. Acknowledgments This work was supported by the Spanish Ministerio de Ciencia e Innovación (MICINN/FEDER) PDI2021-128342OB-I00, by the Agency for Management of University and Research Grants (AGAUR) ref. 2021-SGR-00739 and by the Catalan Institution for Research and Advanced Studies (ICREA) under the ICREA Academia Award. Has also received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 945413. References Di Anibal, Carolina V., Lluís F. Marsal, M. Pilar Callao, and Itziar Ruisánchez. "Surface Enhanced Raman Spectroscopy (SERS) and multivariate analysis as a screening tool for detecting Sudan I dye in culinary spices." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy87 (2012): 135-141.Macias, Gerard, Laura P. Hernández-Eguía, Josep Ferré-Borrull, Josep Pallares, and Lluís F. Marsal. "Gold-coated ordered nanoporous anodic alumina bilayers for future label-free interferometric biosensors." ACS applied materials & interfaces5, no. 16 (2013): 8093-8098.Kumeria, Tushar, Abel Santos, Mohammad Mahbubur Rahman, Josep Ferré-Borrull, Lluís F. Marsal, and Dusan Losic. "Advanced structural engineering of nanoporous photonic structures: Tailoring nanopore architecture to enhance sensing properties." Acs Photonics1, no. 12 (2014): 1298-1306.Santos, Abel, Josep M. Montero-Moreno, Julien Bachmann, Kornelius Nielsch, Pilar Formentín, Josep Ferré-Borrull, Josep Pallares, and Lluís F. Marsal. "Understanding pore rearrangement during mild to hard transition in bilayered porous anodic alumina membranes." ACS applied materials & interfaces3, no. 6 (2011): 1925-1932.Hernández-Eguía, Laura P., Josep Ferré-Borrull, Gerard Macias, Josep Pallarès, and Lluís F. Marsal. "Engineering optical properties of gold-coated nanoporous anodic alumina for biosensing." Nanoscale Research Letters9 (2014): 1-8.Palacios, R., P. Formentín, J. Ferré‐Borrull, J. Pallarés, and L. F. Marsal. "Polymer nanopillars using self‐ordered nanoporous alumina templates." physica status solidi c6, no. 7 (2009): 1584-1586.Vojkuvka, Lukas, Lluís F. Marsal, Josep Ferré-Borrull, Trifon Trifonov, and Josep Pallarés. "Fabrication of self-ordered nanoporous alumina for optical and structural characterization." Contributions to science4, no. 2 (2008): 219-222.Dar, Gohar Ijaz, Elisabet Xifre‐Perez, and Lluis F. Marsal. "Fabrication of Au‐Decorated Al Nanoconcavities Platform for Augmented SERS." Advanced Materials Interfaces(2023): 2300560. Figure 1

Two-step printing bionic self-lubricating composite surface fabricated by selective laser melting ink-printed metal nanoparticles

The combination of self-lubricating materials and surface texture was a promising strategy to improve tribology performance. The designed parameters and manufacturing methods of the textured composite surface were pivotal in fully harnessing this synergistic effect. Inspired by natural structures such as the scapharca subcrenata shell, trimeresurus stejnegeri snakeskin, crocodile, and tree frog toe pad surface, bionic self-lubricating composite surfaces (BSCSs) with different textures were prepared on AISI 4140 steel substrate to enhance tribological properties. These BSCSs combined self-lubricating composite material (SLCM) with copper (Cu) material in bionic patterns using the selective laser melting ink-printing metal nanoparticles manufacturing method. Tribological properties and worn surfaces of the BSCSs with various design parameters were analyzed under dry sliding conditions. Results indicated that the synergy effects of printed Cu and SLCM texture effectively reduced friction coefficient and improved wear resistance of the BSCSs. The SLCM texture density and the size of array element in the BSCSs were found to influence the types of lubricating film formed during the sliding process, thereby affecting the tribological performance. This investigation provided a potential surface design strategy and a more flexible manufacturing method for surface engineering.

Localization of jet electrochemical additive manufacturing with a liquid confinement technique

Electrochemical additive manufacturing (ECAM) is a flexible additive manufacturing method to deposit metallic/metallic-alloys microstructures without any thermally induced residual stresses. The conventional ECAM process suffers from stray deposition leading to reduced dimensional accuracy. Therefore, this paper proposes a novel liquid confinement technique to improve the deposition localization in Jet-ECAM process. Dichloromethane was employed as a second liquid phase to confine and control the flow field distribution of electrolyte as well as localize electric field on the substrate. Thus, the stray deposition induced by spreading electrolyte and hence spreading electric field could be avoided, and the deposition localization was improved. Liquid-liquid two-phase flow model was developed to analyze the flow field characteristic of two-phase flow formed by electrolyte and dichloromethane. Both simulation and observation results indicated that the flow region of the electrolyte on the substrate was well confined by the dichloromethane. The experimental results showed that the deposition localization was improved about 43.84 % compared to that in traditional Jet-ECAM. The inter-electrode gap (IEG) had a significant effect on both electrolyte flow region and current density distribution on the substrate, which affected deposition quality. Additionally, high current density leads to coarsened grains and reduces the deposition quality. Moreover, increasing the reciprocating speed of nozzle could refine the grains of microstructure, but the deposition efficiency was reduced. By employing process parameters of IEG of 100 μm, electric current of 0.0015 A, and the reciprocating speed of 300 μm/s, micro-patterns including both lines and curves were well deposited with a width of 500 μm, height of 60 μm, and a radius of 2 mm (letters G and U) and 2.5 mm (letter D).

Modeling and Control of Layer Height in Laser Wire Additive Manufacturing.

Laser Wire Additive Manufacturing (LWAM) is a flexible and fast manufacturing method used to produce variants of high metal geometric complexity. In this work, a physics-based model of the bead geometry including process parameters and material properties was developed for the LWAM process of large-scale products. The developed model aimed to include critical process parameters, material properties and thermal history to describe the relationship between the layer height with different process inputs (i.e., the power, the standoff distance, the temperature, the wire-feed rate, and the travel speed). Then, a Model Predictive Controller (MPC) was designed to keep the layer height trajectory constant taking into consideration the constraints faced in the LWAM technology. Experimental validation results were performed to check the accuracy of the proposed model and the results revealed that the developed model matches the experimental data. Finally, the designed MPC controller was able to track a predefined layer height reference signal by controlling the temperature input of the system.

Investigation on synergism between additive and subtractive manufacturing for curved thin-walled structure

ABSTRACT Direct energy deposition (DED), as a flexible and economic manufacturing method, has drawn extensive attentions, whereas low surface quality and dimensional accuracy hinder its development. Hybrid manufacturing perfectly solves these problems without introducing additional positioning errors. In this study, we evaluate the effect of the synergies on the forming process of curved thin-walled structures in terms of procedure complexity, microstructures and mechanical properties. A multi-physics model is developed to simulate the DED process and provide guidance for the subsequent subtractive manufacturing (SM) process to better achieve the objective. The results demonstrate that the process procedure of the multiple-cycle hybrid manufacturing (MCHM) presents much more complex than the one-cycle hybrid manufacturing (OCHM). The grain size in the transition region of the MCHMed sample is refined, increasing the localised microhardness. However, the tensile strength and ductility of the MCHMed sample are found slightly lower than those of the OCHMed sample.

Metal fused filament fabrication of the nickel-base superalloy IN 718

This study demonstrates metal fused filament fabrication (MF3) as an alternative additive and highly flexible manufacturing method for free-form fabrication of high-performance alloys. This novel processing, which is similar to Metal injection molding (MIM), enables a significant reduction in manufacturing costs for complex geometries, since expensive machining can be avoided. Utilizing existing equipment and reducing material expense, MF3 can pave the way for new and low-cost applications of IN 718, which were previously limited by high manufacturing costs. Iterative process optimization is used to find the most suitable MF3 process parameters. High relative density above 97% after pressureless sintering can be achieved if temperature profiles and atmospheres are well adjusted for thermal debinding and sintering. In this study, the influence of processing parameters on the resulting microstructure of MF3 IN 718 is investigated. Samples sintered in vacuum show coarse-grained microstructure with an area fraction of 0.36% NbC at grain boundaries. Morphology and composition of formed precipitates are analyzed using transmission electron microscopy and atom probe tomography. The γ/γ″/γ′ phases’ characteristics for IN 718 were identified. Conventional heat treatment is applied for further tailoring of mechanical properties like hardness, toughness and creep behavior. Fabricated samples achieve mechanical properties similar to MIM IN 718 presented in literature.Graphical abstract

Statistical modelling and optimization of print quality and mechanical properties of customized tubular scaffolds fabricated using solvent-based extrusion 3D printing process.

Tissue-engineered tubular scaffolds offer huge potential to heal or replace the diseased organ parts like blood vessels, trachea, oesophagus and ureter. However, manufacturing these scaffolds in various scales and shapes is always challenging and requires progressive technology. Developing a flexible and accurate manufacturing method is a major developmental direction in the field of tubular scaffold fabrication. In this context, the present work presents a novel solvent-based extrusion 3D printing which allows extruding over a rotating mandrel to fabricate tubular scaffolds of polycaprolactone (PCL) and polyurethane (PU). Experimental runs were planned as per the central composite design (CCD) to evaluate the effects of input parameters like infill density, layer thickness, print speed and percentage of PU on the output responses like printing quality and mechanical characteristics. The printing quality was quantified by measuring average surface roughness of the printed scaffolds and mechanical properties were evaluated by measuring radial compressive load, and percentage of elongation. The experimental investigations revealed that printing quality was improved at higher infill densities and was deteriorated at higher print speeds and layer thicknesses. Similarly, the radial compressive load was improved with the increase in infill density and was decreased with an increase in layer thickness, print speed and percentage of PU. The percentage of elongation was found to improve at higher infill densities and percentages of PU and was reduced with an increase in layer thickness and print speed. Additionally, a multi-objective optimization using Genetic Algorithm was used to evaluate the optimum conditions to minimize surface roughness and maximizing radial compression load and percentage of elongation. Finally, a case study was performed by comparing the mechanical properties of tubular organs and scaffolds from the existing reports and results of the present work.

Manufacturing Zero-Waste COVID-19 Personal Protection Equipment: a Case Study of Utilizing 3D Printing While Employing Waste Material Recycling.

COVID-19 pandemic outbreak dictated the extensive use of personal protective equipment (PPE) by the majority of the population and mostly by frontline professionals. This need triggered a sudden demand that led to a global shortage of available PPEs threatening to have an immense contribution to the virus contamination spread. In these conditions, the need for a local, flexible, and rapid manufacturing method that would be able to cope with the increased demand for PPE fabrication arose. 3D printing proved to be such a manufacturing technique since its working principles make it an ideal technology for local, decentralized production of PPEs meeting the local demands. While considered to be more environmentally friendly than conventional fabrication techniques and aligning well with the principles of sustainability and circular economy, 3D printing can produce waste as the result of potential failed prints and material used for the fabrication of support structures. This paper describes the case of utilizing pre-existing FDM 3D printing equipment in an academic facility for the production of PPEs (face shields) and their distribution according to local demands. The plastic wastes produced were forwarded to a recycling process that led to their conversion to 3D filament that would be returned to the academic facility as raw material for future 3D printing operations. The followed procedure minimized 3D printing waste and led to a zero-waste fabrication case that was initiated in a pandemic for a greater-good cause (production of COVID-19 fighting PPEs) while assimilating the values of sustainability and circular economy.Graphical abstract

Research progress in laser direct writing of flexible circuit

<p indent="0mm">At present, the flexible electronics industry is in an important transitional period, and various flexible electronic devices with novel properties and enhanced functions are constantly emerging, from limited flexibility to flexible electronic devices with shape adaptability and ductility. This has greatly stimulated demand for flexible electronic devices. The development of manufacturing technologies for flexible circuits with smaller feature sizes and better performance on larger-format substrates at lower costs has attracted increasing attention. Among various technologies, laser direct writing has proven to be an efficient and flexible manufacturing method that can produce large-area flexible electronic circuits. As a nonlithographic, nonvacuum, and online processing technology, laser direct writing has received considerable attention. It can be employed in the production of circuit electrodes of various substrates, including heat-sensitive flexible substrates, and it has huge application prospects in the production of flexible electronic and energy storage devices, sensors, and wearable electronic devices. On this basis, this article summarizes the latest development in the laser direct writing of flexible circuit (LDWFC) technology for manufacturing flexible circuits. It focuses on the material types and characteristics of the conductive inks suitable for LDWFC in the production of flexible circuits. The LDWFC processing technology is introduced in detail from four aspects: laser sintering technology, laser reduction technology, laser-induced modification technology, and laser auxiliary circuit manufacturing technology. In addition, the application of LDWFC in flexible energy storage devices, tenderness sensors, and flexible displays is introduced, and the development prospects of LDWFC technology in flexible circuit manufacturing are highlighted.

Ohmic contact formation for inkjet-printed nanoparticle copper inks on highly doped GaAs

GaAs compound-based electronics attracted significant interest due to unique properties of GaAs like high electron mobility, high saturated electron velocity and low sensitivity to heat. However, GaAs compound-based electronics demand a significant decrease in their manufacturing costs to be a good competitor in the commercial markets. In this context, copper-based nanoparticle (NP) inks represent one of the most cost-effective metal inks as a proper candidate to be deposited as contact grids on GaAs. In addition, Inkjet-printing, as a low-cost back-end of the line process, is a flexible manufacturing method to deposit copper NP ink on GaAs. These printed copper NP structures need to be uncapped and fused via a sintering method in order to become conductive and form an ohmic contact with low contact resistivity. The main challenge for uncapping a copper-based NP ink is its rapid oxidation potential. Laser sintering, as a fast uncapping method for NPs, reduces the oxidation of uncapped copper. The critical point to combine these two well-known industrial methods of inkjet printing and laser sintering is to adjust the printing features and laser sintering power in a way that as much copper as possible is uncapped resulting in minimum contact resistivity and high conductivity. In this research, copper ink contact grids were deposited on n-doped GaAs by inkjet-printing. The printed copper ink was converted to a copper grid via applying the optimized settings of a picosecond laser. As a result, an ohmic copper on GaAs contact with a low contact resistivity (8 mΩ cm2) was realized successfully.

Effects of 3D printed surface texture on erosive wear

Abstract Additive Manufacturing (AM), which more commonly known as 3D printing, is an extremely popular, fast and flexible manufacturing method. Rectangular prismatic textures are created on a surface via 3D printing technique. It is observed that the surface texture obtained by AM reduces particle erosion by half under the same erosion direction, and the angle of blasting direction on the prepared surface texture has a major effect, where there is an evident change in wear rate when the surface texture is smaller than the particle size. Also, it is seen that small changes in the dimension of the texture has no remarkable effect on particle erosion.

Micro grinding 16MnCr5 hardened steel using micro pencil grinding tools with diameters ∼50 μm

Micro pencil grinding tools (MPGTs) are micro machining tools that have a huge potential for manufacturing fully micro textured surfaces made out of a broad range of hard and brittle materials, finding use in industries like biomedicine and microelectronics. Due to the flexible manufacturing method used to produce MPGTs - the shape of the tool can be adjusted according to the task at hand. Complex freeform microstructures with various cross sections like dovetails or hemispheres can be produced — cross sections that no other process can produce in brittle materials. MPGTs with diameters <50μm however, suffer from a far too short tool life and far too slow achievable feed rates to make the process economical. As part of the tool development process, a parameter study is needed to understand the influence of some of the more important process parameters like feed rate, rotational speed and the tool inclination angle, as well as the grit size. A full factorial experimental design is conducted to determine the importance of each parameter, using an Analysis of Variance (ANOVA) statistical evaluation method. Using the knowledge obtained from the results of this parameter study, optimum parameters were selected for a second case study. Besides increasing the MPGT tool life, the goal was to achieve feed rates beyond 1mm/min.

Spatial Uncertainty Modeling for Surface Roughness of Additively Manufactured Microstructures via Image Segmentation

Despite recent advances in additive manufacturing (AM) that shifts the paradigm of modern manufacturing by its fast, flexible, and affordable manufacturing method, the achievement of high-dimensional accuracy in AM to ensure product consistency and reliability is still an unmet challenge. This study suggests a general method to establish a mathematical spatial uncertainty model based on the measured geometry of AM microstructures. Spatial uncertainty is specified as the deviation between the planned and the actual AM geometries of a model structure, high-aspect-ratio struts. The detailed steps of quantifying spatial uncertainties in the AM geometry are as follows: (1) image segmentation to extract the sidewall profiles of AM geometry; (2) variability-based sampling; (3) Gaussian process modeling for spatial uncertainty. The modeled spatial uncertainty is superimposed in the CAD geometry and finite element analysis is performed to quantify its effect on the mechanical behavior of AM struts with different printing angles under compressive loading conditions. The results indicate that the stiffness of AM struts with spatial uncertainty is reduced to 70% of the stiffness of CAD geometry and the maximum von Mises stress under compressive loading is significantly increased by the spatial uncertainties. The proposed modeling framework enables the high fidelity of computer-based predictive tools by seamlessly incorporating spatial uncertainties from digital images of AM parts into a traditional finite element model. It can also be applied to parts produced by other manufacturing processes as well as other AM techniques.

Nanoimprint lithography for the manufacturing of flexible electronics

Flexible electronics have received considerable attention in academies and industries for their promising applications in enormous fields, such as flexible displays, wearable sensors, artificial skins, and flexible energy devices. Challenges remain in developing a flexible and scalable manufacturing method to facilitate the fabrication of multi-functional structures in a flexible electronic system. Nanoimprint lithography is a high resolution and low-cost approach to fabricate nanostructures over a large area. This paper reviews recent progress of nanoimprint lithography and its applications in flexible electronics. The basic principles, classification, research focus, and critical issues of nanoimprint lithography are elaborated. Then, the advantages of nanoimprint lithography are demonstrated in several typical applications related to flexible electronics, including conductive films, optoelectronic devices, flexible sensors, energy harvesting and storage devices, and bioinspired electronic devices. Finally, the challenges and perspectives of nanoimprint lithography in flexible electronic systems are discussed.

Fabrication of spherical microlens array by combining lapping on silicon wafer and rapid surface molding

Silicon is a promising mold material for compression molding because of its properties of hardness and abrasion resistance. Silicon wafers with carbide-bonded graphene coating and micro-patterns were evaluated as molds for the fabrication of microlens arrays. This study presents an efficient but flexible manufacturing method for microlens arrays that combines a lapping method and a rapid molding procedure. Unlike conventional processes for microstructures on silicon wafers, such as diamond machining and photolithography, this research demonstrates a unique approach by employing precision steel balls and diamond slurries to create microlenses with accurate geometry. The feasibility of this method was demonstrated by the fabrication of several microlens arrays with different aperture sizes and pitches on silicon molds. The geometrical accuracy and surface roughness of the microlens arrays were measured using an optical profiler. The measurement results indicated good agreement with the optical profile of the design. The silicon molds were then used to copy the microstructures onto polymer substrates. The uniformity and quality of the samples molded through rapid surface molding were also assessed and statistically quantified. To further evaluate the optical functionality of the molded microlens arrays, the focal lengths of the microlens arrays were measured using a simple optical setup. The measurements showed that the microlens arrays molded in this research were compatible with conventional manufacturing methods. This research demonstrated an alternative low-cost and efficient method for microstructure fabrication on silicon wafers, together with the follow-up optical molding processes.

3D Printing-Enabled Rapid Reproduction of Mxene Based Supercapacitors

Application of two-dimensional (2D) nanomaterials for energy storage devices such as batteries or supercapacitors has been proposed many times since properties of the materials at such scale offer short ion transport routes and high surface area [1]. Most recently, the potential of Ti3CN transition metal carbides (MXenes) as anodes of Li-ion batteries was proposed [2]. However, realization of such applications has lacked so far a flexible, scalable, reproducible and cost-effective manufacturing method. The fabrication of 2D nanomaterials by liquid phase exfoliation allows production of large amounts of these materials at low prices [3], but fabrication of devices based on such materials at competitive rates is still a challenge. Ink-jet printing is employed by many research groups for fabrication of nanomaterials-based devices since it’s a highly flexible technique enabling to adjust process parameters quickly and to vary the devices’ design dynamically [4]. While on research level ink-jet printing is a very useful tool, the scalability of the process is limited and transition to mass production not trivial. Therefore, it would be favorable to employ techniques which are closer to high volume fabrication in their process principle from first lab experiments on. In this work, a simple yet effective method was employed to rapidly reproduce structures for supercapacitors on various substrates. The method comprises stamps which were 3D printed by fused deposition modelling (FDM) and MXene loaded inks. The very simple process of depositing involves coating the stamp with Ti3CN ink and pressing it onto a substrate subsequently. As stamp printing is a very fast and easy to execute process it provides a proper tool to rapidly produce a large number of identical devices. Various different materials were evaluated to serve as substrates, such as paper, glass and PET, demonstrating the high flexibility of the process. Electrochemical analysis of the devices was performed and comparative results thereof are discussed in this work. Using a 3D printer to fabricate the stamps enables dynamic change of the design of the capacitor to adapt to previously performed tests. The figure shows a stamped capacitor structure on paper substrate, a photograph of 3D printed stamps with varying capacitor designs and a CV graph of said printed device. While being fast and easy to handle in the lab, the working principle of stamp printing relies on the same mechanics as roll to roll printing, which is a high volume printing technology. This approach promises high scalability potential while simultaneously it stays flexible and adaptive to rapid changes making it suitable for research and development works. First results of the electrochemical characterization of the devices show good capacitive behaviors with rectangular CV shapes.

An investigation on the properties of injection-molded pure iron potentially for biodegradable stent application

Metal injection molding (MIM) is a near-net-shape manufacturing process suitable for the production of small-size and complex-shape components. As a cost-effective and flexible manufacturing method, it may have distinct advantages over other methods when it comes to the manufacturing of implantable medical devices. However, up till now, the potential for MIM to be employed in the commercial-scale manufacturing of implantable medical devices has been insufficiently exploited. In the present research, an attempt was made to produce porous pure iron, as a metallic degradable biomaterial potentially for stent application, via the MIM route. The effects of iron powder loading and sintering temperature on the porosity, microstructure, mechanical properties, surface properties and in vitro degradation behavior of MIM iron were investigated. The results obtained were compared to those of cast iron. It was found that the amount of porosity retained in the as-sintered specimens had a major effect on their surface and mechanical properties. MIM iron exhibited strengths between those of magnesium alloys and 316L stainless steel and very high ductility — a specially required property of stent materials. Its degradation rates in Hank's solution were superior to the degradation rate of cast iron. Interestingly, the material made from the feedstock containing 66% of iron powder, above the critical powder loading, showed the highest elongation and a good in vitro degradation rate. In conclusion, MIM is a promising method to be developed as a new route to produce thin-wall tubes for biodegradable stents.

Software Tool Used for Simulation of Metal Spinning Process for Complex Rotational Parts

Metal spinning on NC machine-tools is a very flexible and complex manufacturing method which has a high efficiency for small series of parts and prototype parts. The algorithms used for calculating the roller trajectory during the metal spinning process are usually complicated and hard to apply into production. This article presents an original application developed using Visual LISP that can be used for calculating and then simulating and testing the roller trajectory in the case of manufacturing rotational complex parts by metal spinning. The simulation prevents any errors that can occur during the process of manufacturing before the parts are actually put into production.