Use Of Additive Manufacturing Research Articles

Plantar pressure distribution using personalised 3D printed lattice insoles with distributed stiffness

This work presents a proof-of-concept study on the use of additive manufacturing for developing customised lattice topology insoles, with the aim of redistributing plantar pressures. Four cubic lattice structures were applied to five sections of the moulded insole contours, which were based in 3D foot scans using Ansys material designer to predict material properties. The variation of the elastic modulus across the sections was controlled via the lattice cell structure volume ratio. The insole lattice structures were made from elastic photosensitive liquid resin resulting in flexible parts. A commercially available shoe was used to compare pressure distribution between the original and customised insole. Plantar pressure distribution and peak pressures were measured during standing, walking, and running. Pressure redistribution varied between insole conditions. During standing, the customised insole reduced peak pressure at the left heel, while the right foot experienced increased peak pressure compared to the control insole. Substantial peak pressure reduction was observed on the left foot during walking and running whilst the reduction was much less for the right foot. The study highlights the potential of additive manufacturing for cost-effective, accurate, and personalized insole production, offering material control and pressure redistribution benefits for various applications like injury prevention and rehabilitation.

Additive manufacturing of synthetic rubber ink with high solid content reinforced by networked silica

Abstract Silica is a reinforcing filler commonly used in the production of environmentally friendly tires, as tires reinforced with silica have lower rolling resistance, which translates into reduced energy consumption and improved fuel economy. However, achieving the optimal dispersion of silica within the rubber matrix is crucial for maximizing its reinforcing effects. In this study, a three- dimensionally networked silica (NS) was introduced in various amounts to rubber inks to improve their tensile strength and increase miscibility to enable their use in additive manufacturing. The results show that synthetic rubber ink with a high content of styrene–butadiene rubber (90%) and reinforced by NS possesses adequate viscosity for use in the direct ink write (DIW) process. NS was confirmed to have an impact on the rheological properties and printability of the rubber ink as well as to improve the tensile strength of the printed parts. Different formulations were tested to study and facilitate the vulcanization process and identify the optimal curing conditions as well as the print parameters to use in DIW printing. The successful printing and vulcanization of various printed structures demonstrates the potential for using the developed printable ink in additive manufacturing. This study opens up new possibilities for creating rubber products (such as tire treads) with adequate flexibility and high tensile strength.

Additive Manufacturing in Industry 4.0 and its Implications for Sustainability in Production Processes

Objective: This research aimed to analyze the implications of the use of additive manufacturing for sustainability in production processes. Methodology: The research was characterized as exploratory qualitative approach, which was carried out with 15 professionals from a Brazilian industry. Data collection was conducted through in-depth interviews, and analysis of the speech revealed insights into the environmental implications of additive manufacturing. Results and discussion: As a result, it was evidenced that despite the benefits offered by additive manufacturing for sustainability, such as reducing material waste and personalized production, there are significant challenges to be faced. Concern about the recyclability of materials used in 3D printing has been identified as a critical point, underlining the pressing need to develop more efficient and sustainable recycling processes to deal with the waste generated. In addition, mentioning the importance of considering the full life cycle of products emphasizes the complexity of environmental issues associated with additive manufacturing, requiring holistic approaches that consider environmental impacts at all stages of the process. Conclusion: Therefore, the need for an integrated approach to sustainability in additive manufacturing is highlighted, which not only maximizes the environmental benefits of the technology, but also proactively deals with emerging challenges, thus ensuring a positive impact on the environment.

Additive manufacturing of scalable jet impingement and radial taper enhancements for improved flow boiling performance

Additive manufacturing (AM) offers a unique route to improve flow boiling heat transfer by enabling the fabrication of complex fluidic devices. In this study, two types of advanced jet impingement designs were additively manufactured and tested in subcooled flow boiling with 20 °C of subcooling. The first design is an in-line extended nozzle jet impingement manifold with nozzles off angle to the flow direction that extend towards the heated surface in order to decrease pressure drop and reduce viscous dissipation. The influence of jet velocity was explored and the optimal 3 nozzle design achieved a critical heat flux (CHF) of 191 W/cm2 and heat transfer coefficient (HTC) of 42.1 kW/m2K at a pressure drop of 3.4 kPa. This represents a 78% increase in CHF and 64% increase in HTC compared to open flow conditions. Following this, a second more complex design was created combining jet impingement, tapered flow paths, radial flow, and intricate fluidic routing to further improve heat transfer. This complex design would be extremely difficult to manufacture without additive techniques and resulted in a CHF of 375 W/cm2 and HTC of 74.2 W/m2K at a pressure drop of 3.5 kPa at a flow rate of 300 mL/min. This represented a 250% and 189% increase in CHF and HTC respectively over open channel flow conditions at a low pressure drop. These designs are easily scalable, and represent a new class of “on surface” flow boiling jet impingement enhancement techniques enabled through the use of additive manufacturing of polymeric materials.

Hybrid manufacturing approach for landing gear applications: WAAM Ti–6Al–4V on forged Ti–5Al–5Mo–5V–3Cr

High-strength metastable β-titanium alloys like Ti-5553 (Ti–5Al–5Mo–5V–3Cr) are frequently used in highly loaded aerospace components. Such aerospace parts tend to be expensive to traditionally manufacture due to current industry process limitations such as inflexibility for complex geometries, costs related to tooling for large forgings, extended lead times, poor machinability and high material waste. These challenges are leading to increased interest in exploring alternative manufacturing routes. This work investigates the use of additive manufacturing to deposit cost-effective and machinable Ti-64 (Ti–6Al–4V) alloy onto a forged Ti-5553 alloy substrate. The microstructure evolution, microhardness and tensile properties have been investigated for both the as-deposited as well as for stress relief heat-treated conditions. The results confirmed the formation of coarse columnar β grains with a fine basketweave α structure. The heat affected zones (HAZs) developed in the Ti-5553 substrate material from the cyclic thermal fluxes introduced from the melt-pool were characterized by a gradient microstructure of dissolving constituent phases with nearing proximity to the fusion zone. Tensile testing in the as-deposited condition was characterised with a UTS of 884 MPa and a ductility of 15%. Tensile samples extracted across the substrate-deposit interface all failed in the WAAM Ti-64 material and demonstrated comparatively greater strength but poorer ductility. A band of tensile residual stresses was imparted along the substrate, but was adequately stress relieved after heat-treatment at 600 °C. The heat-treatment led to the formation of more homogeneous α-phase laths throughout the HAZ of the Ti-5553 material and provided overall improvements to the strength and ductility.

The energy performance assessment method to establish the best part build orientation in additive manufacturing

AbstractThe growing use of additive manufacturing (AM) processes pushes research towards studying methods to reduce their environmental impact. The part build orientation is a significant process variable, which can be chosen through the Energy Performance Assessment (EPA), a straightforward method. The paper presents a method for identifying the best part build orientation considering energy consumption. The EPA has been adapted for this purpose, resulting in an approach based on four steps. The method was employed to determine the best printing direction for three parts and two AM technologies.

The Use of Additive Manufacturing Techniques in the Development of Polymeric Molds: A Review.

The continuous growth of additive manufacturing in worldwide industrial and research fields is driven by its main feature which allows the customization of items according to the customers' requirements and limitations. There is an expanding competitiveness in the product development sector as well as applicative research that serves special-use domains. Besides the direct use of additive manufacturing in the production of final products, 3D printing is a viable solution that can help manufacturers and researchers produce their support tooling devices (such as molds and dies) more efficiently, in terms of design complexity and flexibility, timeframe, costs, and material consumption reduction as well as functionality and quality enhancements. The compatibility of the features of 3D printing of molds with the requirements of low-volume production and individual-use customized items development makes this class of techniques extremely attractive to a multitude of areas. This review paper presents a synthesis of the use of 3D-printed polymeric molds in the main applications where molds exhibit a major role, from industrially oriented ones (injection, casting, thermoforming, vacuum forming, composite fabrication) to research or single-use oriented ones (tissue engineering, biomedicine, soft lithography), with an emphasis on the benefits of using 3D-printed polymeric molds, compared to traditional tooling.

Reinforced HDPE with optimized biochar content for material extrusion additive manufacturing: morphological, rheological, electrical, and thermomechanical insights

The development of efficient and sustainable composites remains a primary objective of both research and industry. In this study, the use of biochar, an eco-friendly reinforcing material, in additive manufacturing (AM) is investigated. A high-density Polyethylene (HDPE) thermoplastic was used as the matrix, and the material extrusion (MEX) technique was applied for composite production. Biochar was produced from olive tree prunings via conventional pyrolysis at 500 °C. Composite samples were created using biochar loadings in the range of 2.0–10.0 wt. %. The 3D-printed samples were mechanically tested in accordance with international standards. Thermogravimetric analysis (TGA) and Raman spectroscopy were used to evaluate the thermal and structural properties of the composites. Scanning electron microscopy was used to examine the fractographic and morphological characteristics of the materials. The electrical/dielectric properties of HDPE/biochar composites were studied over a broad frequency range (10–2 Hz–4 MHz) at room temperature. Overall, a laborious effort with 12 different tests was implemented to fully characterize the developed composites and investigate the correlations between the different qualities. This investigation demonstrated that biochar in the MEX process can be a satisfactory reinforcement agent. Notably, compared to the control samples of pure HDPE, biochar increased the tensile strength by over 20% and flexural strength by 35.9% when added at a loading of 4.0 wt. %. The impact strength and microhardness were also significantly improved. Furthermore, the Direct current (DC) conductivity of insulating HDPE increased by five orders of magnitude at 8.0 wt. % of biochar content, suggesting a percolation threshold. These results highlight the potential of C-based composites for the use in additive manufacturing to further exploit their applicability by providing parts with improved mechanical performance and eco-friendly profiles.Graphical

Manufacturing of Brake Pads and Brake Shoes Through Additive Manufacturing with Boron Carbide (B4C) and Molybdenum Disulfide (MoS2) as Additives

Abstract: An essential component of car performance and safety is the production of brake shoes and pads. This study investigates how to improve these components by incorporating innovative materials using additive manufacturing techniques. Because of their special qualities, molybdenum disulfide (MoS2) and boron carbide (B4C) are used as additives. MoS2, which is well-known for its solid lubricating qualities, seeks to improve the frictional properties, while B4C, which is recognized for its extraordinary hardness, is added to increase wear resistance. Brake component performance can be maximized by precisely controlling the material composition and complex designs through the use of additive manufacturing. The combination of B4C and MoS2 provides a well-rounded solution by tackling the wear and friction issues that are essential for efficient braking. In order to obtain increased frictional stability, decreased wear rates, and greater durability, this study looks into the best ratios and distribution of these additives. This study seeks to contribute to the development of next generation brake systems, ensuring improved safety, efficiency, and lifetime in automotive applications by utilizing modern manufacturing techniques and combining B4C and MoS2. The results are anticipated to have an impact on the production of high-performance components with customized material qualities in the automobile industry as well as the larger field of additive manufacturing.

Enhancement of strength and ductile-brittle transition temperature of SA508 Gr.3 low-alloy steel by controlling heat accumulation in laser powder-directed energy deposition

The safety and longevity of small modular reactors are affected by reactor pressure vessels, which are complex integral components made of SA508 Gr.3 low-alloy steel. In this study, the impacts of heat accumulation on the microstructural and mechanical characteristics (tensile properties and Charpy V-notched impact energy) of SA508 Gr.3 steel fabricated using laser powder-directed energy deposition were investigated. Rectangular samples were prepared using long raster and short raster scanning strategies for changing heat buildup, and the mechanical tests were conducted depending on build direction. The time-temperature profile measured at a fixed point in the long raster sample showed a lower maximum temperature and a higher cooling rate, indicating lower heat accumulation compared to that of the short raster sample. In each build direction, the yield strength of the long raster sample was 45.8 %–60.5 % higher and its ductile-brittle transition temperature was 76.8–103.8 °C lower than that of the short raster sample. Additionally, compared to conventionally made samples and without requiring heat treatment, the long raster sample exhibited over a 45 % increase in yield strength and a 22.7 °C reduction in the ductile-brittle transition temperature. The superior combination in long raster samples is induced by smaller effective grain size, smaller cementite, and a higher pre-existing dislocation density. The results emphasize the importance of controlling heat accumulation throughout the additive manufacturing process and provide valuable insights into the use of additive manufacturing for manufacturing reactor pressure vessels in the nuclear industry.

Weldability of Additively Manufactured Powder Bed Fusion 316L Stainless Steel Using Arc and Laser Welding

The use of additive manufacturing for metallic materials presents a wide range of possibilities for industrial applications. The technology offers several advantages, including weight optimisation and the ability to create complex geometries. However, because of the inherent characteristics of the manufacturing process, the dimensions of the produced objects are frequently constrained. In some cases, it may be necessary to join two additively manufactured parts together or to join such parts with an existing, conventionally manufactured structure. Evaluating welding processes for joining additively manufactured workpieces is a crucial step in this development. In this work, the welding of additively manufactured powder bed fusion 316L stainless steel components is discussed. The welding processes considered are manual TIG, manual and robotic MIG/MAG and laser welding. All optimised welds were of good quality and did not show any weld imperfections. All welds fulfil the requirements of standard ISO 15614-1 for the tensile and bend test results and for the hardness values. It can be concluded that the investigated processes are feasible for welding additively manufactured parts.

ADDITIVE MANUFACTURING – NEW TRENDS AND MARKET ANALYSIS

AbstractAdditive manufacturing (AM) is the industrial production name for 3D printing, a computer‐controlled process that creates three dimensional objects by deposing materials, usually in layers. The improvement of the techniques of AM (decrease of deposition time and/or decrease of the cost of the solution) is leading to an increase of the competitiveness of the solution and therefore the use of additive manufacturing in different applications, namely Civil/Structural Engineering application, is increasing significantly. In this study, a market trend analysis along with some examples of possible applications of AM in different fields of construction is addressed.

SYNTHESIS OF DESIGN SOLUTIONS FOR THE DESIGN OF SHOVEL MACHINES MANUFACTURED BY ADDITIVE METHODS

Rocket and space technology is developing rapidly, opening up new opportunities for space exploration and space infrastructure development. Due to constant technological progress and innovations in the field of rocketry, modern rockets have become more reliable, powerful and efficient than previous models. One of the key areas in the modern production of space technology is the use of additive manufacturing, also known as 3D printing. This technology makes it possible to produce complex parts quickly, efficiently and with high precision using a variety of materials, including special metals and composite materials. The introduction of additive manufacturing solves several problems in the manufacture of parts for rocket and space technology. In the modern engineering design of vane machines used in turbine engines, compressors and other units, there is a growing interest in the use of advanced manufacturing technologies, including additive manufacturing. These manufacturing methods, in which components are created by layering material on top of digital 3D models, provide unique opportunities for creating complex geometries that were previously unattainable with traditional manufacturing methods. The purpose of the article is to investigate the synthesis of design solutions in the design of shovel machines, focusing on the use of additive manufacturing methods. First of all, it analyzes the advantages of these methods in the production of blade parts, such as reducing weight and material consumption, increasing the efficiency and strength of parts, as well as the possibility of creating individual and unique designs, taking into account the requirements of critical speed calculations. The geometry optimization is considered and the strength calculations of the structures before and after optimization are performed. The paper concludes with the prospects for the development of the use of additive technologies in the production of blade machines and indicates the possibilities for further research and improvement in this area.

Energy Efficiency in Additive Manufacturing: Condensed Review

Today, it is significant that the use of additive manufacturing (AM) has growing in almost every aspect of the daily life. A high number of sectors are adapting and implementing this revolutionary production technology in their domain to increase production volumes, reduce the cost of production, fabricate light weight and complex parts in a short period of time, and respond to the manufacturing needs of customers. It is clear that the AM technologies consume energy to complete the production tasks of each part. Therefore, it is imperative to know the impact of energy efficiency in order to economically and properly use these advancing technologies. This paper provides a holistic review of this important concept from the perspectives of process, materials science, industry, and initiatives. The goal of this research study is to collect and present the latest knowledge blocks related to the energy consumption of AM technologies from a number of recent technical resources. Overall, they are the collection of surveys, observations, experimentations, case studies, content analyses, and archival research studies. The study highlights the current trends and technologies associated with energy efficiency and their influence on the AM community.

Lightweight and High-Stiffness Metal Optical Systems Based on Additive Manufacturing.

To build a long-wave infrared catadioptric optical system for deep space low-temperature target detection with a lightweight and wide field of view, this work conducted a study that encompasses a local cooling optical system, topology optimization-based metal mirror design, and additive manufacturing. First, a compact catadioptric optical system with local cooling was designed. This system features a 55 mm aperture, a 110 mm focal length, and a 4-degree by 4-degree field of view. Secondly, we applied the principles of topology optimization to design the primary mirror assembly, the secondary mirror assembly, and the connecting baffle. The third and fourth modes achieved a resonance frequency of 1213.7 Hz. Then, we manufactured the mirror assemblies using additive manufacturing and single-point diamond turning, followed by the centering assembly method to complete the optical assembly. Lastly, we conducted performance testing on the system, with the test results revealing that the modulation transfer function (MTF) curves of the optical system reached the diffraction limit across the entire field of view. Remarkably, the system's weight was reduced to a mere 96.04 g. The use of additive manufacturing proves to be an effective means of enhancing optical system performance.

Recycled PETg embedded with graphene, multi-walled carbon nanotubes and carbon black for high-performance conductive additive manufacturing feedstock.

The first report of conductive recycled polyethylene terephthalate glycol (rPETg) for additive manufacturing and electrochemical applications is reported herein. Graphene nanoplatelets (GNP), multi-walled carbon nanotubes (MWCNT) and carbon black (CB) were embedded within a recycled feedstock to produce a filament with lower resistance than commercially available conductive polylactic acid (PLA). In addition to electrical conductivity, the rPETg was able to hold >10 wt% more conductive filler without the use of a plasticiser, showed enhanced temperature stability, had a higher modulus, improved chemical resistance, lowered levels of solution ingress, and could be sterilised in ethanol. Using a mix of carbon materials CB/MWCNT/GNP (25/2.5/2.5 wt%) the electrochemical performance of the rPETg filament was significantly enhanced, providing a heterogenous electrochemical rate constant, k0, equating to 0.88 (±0.01) × 10-3 cm s-1 compared to 0.46 (±0.02) × 10-3 cm s-1 for commercial conductive PLA. This work presents a paradigm shift within the use of additive manufacturing and electrochemistry, allowing the production of electrodes with enhanced electrical, chemical and mechanical properties, whilst improving the sustainability of the production through the use of recycled feedstock.

Recent Advances in Adhesive Bonding of 3D-Printed Parts and Methods to Increase their Mechanical Performance

The use of additive manufacturing (AM) has revolutionized the production of polymer-based materials, offering a wide range of design possibilities and geometric complexity. However, due to the limitations of 3D printers to produce large parts, the parts often must be printed in several separate components and further joined together to obtain the final 3D-printed part. 3D printing can be used to produce only the most complex parts, which can be further combined with simple, non-printed parts from other materials to make the final product. One way to join 3D-printed part is an adhesive-bonded method. This paper focuses on the recent advances in adhesive bonding techniques for 3D-printed parts and explores various methods to enhance their mechanical performance. The benefits and limitations of each technique were discussed, and highlighted promising paths for future research. Finally, this paper provides a comprehensive overview of the current strategies to improve the mechanical performance of adhesive joints with AM-based adherents, offering guidance for the design and fabrication of high-performance structures in a range of applications. It was concluded that the configuration of the bonding area represents an essential parameter that directly influences the bonding strength and overall structural integrity of AM adhesive joints, and that the implementation of customized joint geometries can lead to a substantial enhancement in the joint strength of 3D-printed parts. The incorporation of reinforcing materials, optimization of the printing parameters of adherents, pre and post-treatment methods show potential in enhancing the bonding strength of the 3D-printed joints. The synergistic integration of these cutting-edge technologies can yield mutual advantages that complement each other, ultimately resulting in an enhanced overall performance for AM parts.

Study of methane upgrading using an activated carbon 3D-printed adsorbent

Although Maxsorb is a commercially available powder-form material, to be used in adsorption-based processes, its handling is easier if used with a structured geometry. Indeed, in the monolithic form, activated carbons have shown the potential to be used in adsorption-based applications. The use of additive manufacturing (AM) allows the development of structured adsorbents with adaptable geometries. In this work, Maxsorb activated carbon was 3D-printed into a monolithic structure using a polymeric binding agent, carboxymethylcellulose (CMC). The monolith was obtained through direct writing of filaments of an ink containing the adsorbent and the binding agent in a layered way, according to a pre-established pattern. The material was comprehensively characterized by N2 physisorption at 77 K and CO2 adsorption at 273 K to analyze the porous structure, SEM, and mercury porosimetry to evaluate the macrostructure porosity. To examine the affinity of CH4 and N2 with the adsorbent, pure adsorption equilibrium isotherms of these two gases on the 3D-printed monolith were measured at 303, 333, and 373 K by a gravimetric method. The adsorption capacities were compared to the ones of the original powder. The activated carbon materials showed a higher affinity to CH4. Furthermore, the adsorption equilibrium data of CO2 and Ar were also assessed. For all gases, the adsorption capacities decreased upon shaping. The monolith's CH4/N2 ideal selectivity was compared with its pristine powder (2.84 vs. 3.54). The CH4/N2 separation performance was also assessed through dynamic breakthrough tests. The experimental breakthrough curves were well predicted using a mathematical model.

Mechanical Properties of 3D-Printed Carbon Fiber-Reinforced Cement Mortar

The 3D printing process is different from traditional construction methods of formwork casting due to the use of additive manufacturing. This study develops a suitable 3D-printed carbon fiber-reinforced cement mortar (CFRCM) considering the extrudability, fluidity, setting time, and buildability of the CFRCM. The difference in compressive strength and flexural strength between 3D-printed specimens and conventional cast specimens was investigated by varying the amount of carbon fiber added (carbon fiber to cement ratio, 2.5 vol.‰, 5 vol.‰, 7.5 vol.‰, and 10 vol.‰) and the curing times (7th day and 28th day). The results of the experiments indicate that the addition of 6 wt.% cement accelerators to the cementitious mortar allows for a controlled initial setting time of approximately half an hour. The fluidity of the CFRCM was controlled by adjusting the dosage of the superplasticizer. When the slump was in the range of 150 mm to 190 mm, the carbon fiber to cement ratio 2.5 vol.‰ could be incorporated into the cementitious mortar, enabling the printing of hollow cylinders with a height of up to 750 mm. Comparing the 3D-printed specimens with the traditionally cast specimens, it was found that the addition of a carbon fiber to cement ratio of 7.5 vol.‰, and 10 vol.‰ resulted in the optimal compressive strength and flexural strength, respectively.

Large format additive manufacturing of polyethylene terephthalate (PET) by material extrusion

Polyethylene terephthalate (PET) is an engineering material widely used in packaging and cosmetics, given its excellent mechanical properties, water resistance and recyclability. PET is typically manufactured by injection blow molding but its use in additive manufacturing (AM) is not spread enough due to its (semi)crystalline behavior, which makes it difficult to process by Material Extrusion (ME) technologies. Alternatively, polyethylene terephthalate glycol copolymer (PETG), a fully amorphous material, is used in these technologies. However, PETG has worse mechanical properties than PET. In this context, this work studies the viability of different commercial PET by ME for Large Format Additive Manufacturing (LFAM). While PET for general purposes (PET1 and PET2) could not be printed, a marketable PET for thick-walled products (PET3) allowed to manufacture different objects by ME-LFAM with good dimensional accuracy. DSC and XRD studies evidenced that its slow crystallizing behavior was key to obtaining a proper flow and a successful printing. Young’s modulus and tensile strength of PET3 was significantly higher than those of PETG, both from this work and in previous reports found in the literature, since it remains semicrystalline after printing. This allows expanding the library of materials available for AM, positioning PET as a potential material for those industrial applications where PETG does not meet the necessary mechanical requirements.