Abstract Additive Manufacturing Techniques Research Articles

Additively Manufacturing Mining Tools

Abstract Additive manufacturing techniques give the mining industry a chance to revolutionize the conceptualization, prototyping, and production of mining tools, including using WC-Fe, Ni-based matrix coatings that display exceptional properties. The article includes a case study involving the successful utilization of WC-NiCrBSi mixed powder as a protective coating on AISI 9310 steel components to enhance wear resistance and durability for mining tool applications.

An experimental study on the role of manufacturing parameters on the dry sliding wear performance of additively manufactured PETG

Abstract Additive manufacturing (AM) is a versatile and promising method for rapid prototyping and advanced design applications. Owing to its unique potential for fast production rates, and capacity of creating complex shapes, the number of researches on AM techniques have increased day by day in the technical literature. In this work, contrary to common literature efforts focused on mechanical properties, friction and wear behaviors of additively manufactured PETG samples were analyzed experimentally. As a methodology, fused filament fabrication (FFF) was selected. In order to explore the influence of manufacturing factors on wear properties, layer thickness (0.1, 0.2, and 0.3 mm), infill rate (40, 60, 80, and 100%), and building direction (vertical and horizontal) were changed. Before the friction tests, dimensional accuracy, hardness, and surface roughness measurements were conducted to interpret better the wear results. In addition, macroscopic and microscopic inspections were performed to determine the correct reason behind the deformation. From the data collected during the tests, there was a positive interaction between volume loss and layer thickness. Besides, there was no direct interaction between infill rate/building direction and coefficient of friction. In comparison with vertically built samples, horizontally built samples were subjected to more plastic deformation, and their worn surfaces were severely damaged.

High-density WC–45Cr–18Ni cemented hard metal fabricated with binder jetting additive manufacturing

ABSTRACT Additive manufacturing techniques provide alternative methods to the conventional powder metallurgy for the fabrication of difficult-to-be-machined hard metals. Binder Jetting is particularly suitable for the fabrication of crack-free hard metals as compared to other energy-based additive manufacturing techniques since there is no direct high energy heat input during the 3D printing process. To explore the fabrication process of hard metals and their potential applications, high-density crack-free WC–45Cr–18Ni parts were fabricated using Binder Jetting and sintering in this study. The sintering temperature of 1350°C was found to contribute to the best combination of properties with 98.63% density, >1200 HV 0.3 hardness, compression strength >2200 MPa and compressive elastic modulus of 142 GPa. These parts also possess good oxidation resistance, corrosion resistance and dimensional stability. The Binder Jetting fabricated WC–45Cr–18Ni part shows the potential to be applied as mould material working at high temperatures and where corrosion, oxidation and wear resistance are required.

Influence of different materials used for 3D printing in miniature speaker enclosure development

Additive manufacturing techniques are commonly used in industry and mechanical prototyping. The past years brought rapid growth in this technology development, also in the speaker cabinets manufacturing industry. We observe numerous DIY projects on the market based on the 3D printed cabinet parts; however, this technology also offers novel options that should be investigated and documented. In the current state of the art, the basic properties and construction aspects for speaker acoustic performance is not provided as the 3d printing technique is usually treated as the tool for other projects' development. This paper will provide a detailed comparison of the most common 3D printing materials used in FDM techno9logy, such as PLA, TPE, PET-G, and others with different mechanical properties. Example enclosure for a loudspeaker of 37 mm diameter will be printed in different shapes and compared for frequency and sensitivity differences. The results will be discussed, investigating the possible use of different than traditional rigid plastic enclosures and new options using complicated geometry shapes possibly to manufacture with 3D printing techniques.

Microstructure and strain rate-dependent deformation behavior of PBF-EB Ti6Al4V lattice structures

Abstract Additive manufacturing techniques enable the fabrication of new lightweight components with tailored mechanical properties. Considering current application fields, components are often over-dimensioned since a lack of data regarding the mechanical properties under compression or tensile loading at high strain rates is present. In this work, the influence of various strain rates on the mechanical properties of electron beam powder bed fusion Ti6Al4V lattice structures was investigated. In order to capture the damage mechanisms that occurred, a single unit cell plane was considered. In terms of mechanical characterization, high-speed tensile tests at nominal strain rates from 0.025 to 250 s-1 were carried out. By the additional use of a high-speed camera system and subsequent digital image correlation, an investigation of material reactions during shortest test times was enabled. Based on the results, a positive strain rate dependency was identified for yield and ultimate tensile strength for both investigated lattice types. In detail, an increase in ultimate tensile strength of 16 % for BCC- and 20 % for F2CCZ-specimens could be detected.

Increasing Throughput in Fused Deposition Modeling by Modulating Bed Temperature

Abstract Additive manufacturing (AM) techniques, such as fused deposition modeling (FDM), are able to fabricate physical components from three-dimensional (3D) digital models through the sequential deposition of material onto a print bed in a layer-by-layer fashion. In FDM and many other AM techniques, it is critical that the part adheres to the bed during printing. After printing, however, excessive bed adhesion can lead to part damage or prevent automated part removal. In this work, we validate a novel testing method that quickly and cheaply evaluates bed adhesion without constraints on part geometry. Using this method, we study the effect of bed temperature on the peak removal force for polylactic acid (PLA) parts printed on bare borosilicate glass and polyimide (PI)-coated beds. In addition to validating conventional wisdom that bed adhesion is maximized between 60 and 70 °C (140 and 158 °F), we observe that cooling the bed below 40 °C (104 °F), as is commonly done to facilitate part removal, has minimal additional benefit. Counterintuitively, we find that heating the bed after printing is often a more efficient process for facile part removal. In addition to introducing a general method for measuring and optimizing bed adhesion via bed temperature modulation, these results can be used to accelerate the production and testing of AM components in printer farms and autonomous research systems.

Icosahedral structure influence on the microstructural and mechanical properties of laser additive manufactured (LAM) titanium alloy grade 5

Abstract Additive manufacturing technique has become one of the more prominent manufacturing techniques over the years. The applications of this manufacturing technique are boundless as new process parameters of the operation affects the new structure of the components and gives extended applications. Researchers need to be intentional about A.M. technology before it can have extended applications in aerospace, medical and shipping industries. These composites were engineered from the deposition of enhanced materials (Al-Cu-Ti) in powdered form on titanium alloy (Ti-6Al-4 V), by investigating the implications, impacts and effects of the selected parameters for LMD operation on the metallurgical and mechanical properties present on the enhanced coated surface of the composite. The microstructural evolution and defects were investigated at a much higher magnification using a Scanning Electron Microscope (SEM), supported by Energy Dispersive Microscopy (EDS) and optical microscopy (OPM). The Microhardness of the samples (composites) were investigated using a Vickers hardness tester and X-Ray Diffraction (XRD) analysis was performed on the fabricated composites. The measurements of the hardness decrease with a higher laser power with a value of 1000 W and a lower scanning speed of 0.8 m/min. Hence, an increased scanning speed with a value of 1.0 m/min and lower laser power with a value of 900 W produced the enhanced hardness hybrid coatings (1117.2 HV1.0).

Internal Surface Quality Enhancement of Selective Laser Melted Inconel 718 by Abrasive Flow Machining

Abstract Additive manufacturing (AM) technology enables a new way for fabricating components with complex internal surfaces. Selective laser melting (SLM), being one of the most common AM techniques, is able to fabricate complex geometries with superior material properties. However, due to the poor surface quality, the fabricated internal surfaces cannot meet the specifications for some real applications. To achieve the required internal surface condition, post-polishing process is essential. As one of the most prominent processes for finishing inaccessible surfaces with a wide range of materials, abrasive flow machining (AFM) shows great potential to polish AM internal surfaces. Hence, this paper presents an analytical and experimental study on the internal surface quality improvement of SLM Inconel 718 by AFM, aiming to verify the feasibility of AFM on internal surface quality improvement. The surface evolution process was modeled, and the effects of process parameters on surface and subsurface quality were evaluated. The results show that good surface roughness was obtained at the medium conditions of high viscosity, large particle size, low extrusion pressure, and low temperature. The surface morphology was greatly affected by the medium particle size which showed consistency with the surface evolution model that small abrasive particles are unable to overcome the width and depth of the valleys, resulting in the formation of craters. The partially melt layer was effectively removed, and no subsurface damage was induced.

Determination of the anisotropic fatigue behaviour of additively manufactured structures with short-time procedure PhyBaLLIT

Additive Manufacturing techniques provide completely new possibilities in component design and creation of innovative material structures. To utilize the whole potential of Additive Manufacturing, the microstructure, the mechanical properties and their interrelations as well as their relationship to the Additive Manufacturing process parameters are essential. Investigations of the fatigue behaviour of additively manufactured (AM-) metallic materials are still available in limited extent. However, as a prerequisite for efficient and reliable use of AM-components in safety relevant structures, sound knowledge of fatigue behaviour and properties of these structures is indispensable. A central aspect in Additive Manufacturing is the anisotropic mechanical behaviour under monotonic and cyclic loading in dependency on the building direction [1, 2]. In the present work, the microstructure and mechanical properties of Selective Laser Melted (SLM) as well as Laser Deposition Welded (LDW) AISI 316L stainless steel specimens are investigated with special focus on the influence of the building direction. The investigated specimens are built in horizontal and vertical direction, resulting in layer planes oriented parallel and perpendicular to the loading direction, respectively. The fatigue tests have been performed on a servohydraulic testing system with measurement of stress-strain-hysteresis as well as of plastic deformation induced changes in temperature and specific electrical resistance. S-Nf-curves in the HCF-regime of AM-specimens have been determined with the time and material efficient Physically Based Lifetime calculation procedure PhyBaLLIT [3]. Anisotropic fatigue behaviour of the different AM-specimens has been rated with load increase tests (LIT) and the usage of S-Nfcurves calculated by the PhyBaLLIT method.

Investigations on the Additive Manufacturing and Heavy Wire Bonding Capability of Selective Laser-Melted Circuit Carriers

Abstract Additive manufacturing (AM) provides tool-free and direct manufacturing of complex geometries simultaneously integrating various functions into components. Though AM techniques are widely used in various sectors, the application into electronics production has not yet been explored. In electronics production, substrate development has high relevance due to their multifunctionality through electrically connecting components and providing mechanical support. This contribution introduces an innovative approach based on selective laser melting (SLM) in the development of high-temperature substrates through additive layered manufacturing. Furthermore, possibilities and challenges that come along with the process combination of SLM and heavy wire bonding are investigated. Wire bonding capability is analyzed on untreated as well as on postprocessed surfaces. The influence and effectiveness of various steps of postprocessing such as cleaning, sand blasting, and grinding are analyzed. Thus, interdependencies between both manufacturing process as well as postprocessing can be revealed. The effect of surface roughness and hardness of the assembly partner are investigated as well. The primary characteristics besides the bond parameters that influence the wire bonding capability are focused in this article. The process stability and the interconnection quality are evaluated by optical nondestructive laser microscopic analysis. Destructive pull and shear tests and metallographic cross sections are performed to evaluate the adhesion characteristics. By a profound understanding of all interdependencies between the two processes, a flexible manufacturing technology for power devices can be established.

Feasibility Studies on Selective Laser Melting of Copper Powders for the Development of High-temperature Circuit Carriers

Abstract Additive manufacturing (AM) has the potential to lead significant changes in the present state-of-the-art production processes. This provides tool-free and direct manufacturing of complex geometries simultaneously integrating various functions into components. Though AM techniques are widely used in various sectors, the application into electronics production has been not yet explored. In electronics production, substrate development has high relevance due to their multi-functionality in giving the mechanical support and electrically connecting electronic components. This contribution introduces an innovative approach in the development of high-temperature substrates through additive layered manufacturing. The technique used in the investigations was selective laser melting (SLM) of copper based powder materials mainly bronze alloy and pure copper, for the generation of conductive patterns on ceramic surfaces. The process parameters for the SLM technique and the influential factors in the generation of conductive structures are discussed in detail.

Advances in Additive Manufacturing Processes and Materials

Additivemanufacturing (AM), also known as rapid prototyping or 3Dprinting, generally refers to techniques that produce three-dimensional parts by adding material gradually in a layer by layer fashion. In this sense, AMdiffers fundamentally from forming and subtractive techniques. This special issue intends to put together research and developments in AM, particularly related to new manufacturing processes and/or to alternative feedstock materials and products. Polymer and metal-based raw materials and products have been extensively investigated inAMtechniques. Recently, ceramic, glass, and composite materials have been additionally used both in commercial and in innovative AM processes. The material compositions and processing steps used for shaping or finishing the structure of AM products are responsible for final properties and performance. Recent advances in sensors, micromechanics, computational modelling, and simulation have enhanced AM technologies. As complex parts become easier to build and the equipment and skills needed to build them become more and more common, innovative approaches are achievable. Additionally, this evolution opens up new fields of application,moving it from being a prototyping tool to a final productmanufacturing process (rapidmanufacturing). This special issue explores the development of new products and applications throughAMprocesses. Selected investigations contributed to this issue with original research that analyze feedstock materials, process parameters, and their effects onmechanical, physical, and other properties in prototypes or customized parts fabricated by AM techniques. The topics presented in this issue include diverse materialsmanufactured by representative AMprocesses, as summarized below:

<i>In Vitro</i> Analysis of Hydroxyapatite Coated Bio-Additive Manufactured Implant

Additive Manufacturing (AM) - is a technology that fabricates the parts directly from 3D CAD model without the need of any process planning. The convergence of AM and life science has evolved into a new paradigm called Bio-Additive Manufacturing (BAM). In this paper, Hydroxyapatite (HA) powder was coated over the customized implant, which will serve as a good candidate for bone substitutes due to its chemical and structural similarity to bone. Computer Tomography (CT) scan data of human tibia bone was collected and stacked in MIMICS image processing software, which converts it into 3D data, then implant was fabricated using Selective Laser Sintering (SLS), an AM technique with polyamide powder. Hydroxyapatite powder was synthesized by wet chemical process and coated over implant using plasma spray coating machine. This coating will produce an intermediate region between the bone and the implant, which will stimulate the tissue growth and bone contact. Micrograph of coated and uncoated implant was analyzed using SEM and EDX. For In-Vitro study human mesenchymal cell was cultured over the coated implant. The viability and proliferation of the cells was studied by examining the morphology of the cell. Thus the implant was fabricated using SLS technique and coated with hydroxyapatite powder which exhibits a favorable and good response to enhance tissue growth.