Metal 3D Printing Research Articles

Enhanced osseointegration through direct energy deposition porous coating for cementless orthopedic implant fixation

Direct energy deposition (DED) is a newly developed 3D metal printing technique that can be utilized on a porous surface coating of joint implants, however there is still a lack of studies on what advantages DED has over conventional techniques. We conducted a systematic mechanical and biological comparative study of porous coatings prepared using the DED method and other commercially available technologies including titanium plasma spray (TPS), and powder bed fusion (PBF). DED showed higher porosity surface (48.54%) than TPS (21.4%) and PBF (35.91%) with comparable fatigue cycle. At initial cell adhesion, cells on DED and PBF surface appeared to spread well with distinct actin stress fibers through immunofluorescence study. It means that the osteoblasts bind more strongly to the DED and PBF surface. Also, DED surface showed higher cell proliferation (1.27 times higher than TPS and PBF) and osteoblast cell activity (1.28 times higher than PBF) for 2 weeks culture in vitro test. In addition, DED surface showed better bone to implant contact and new bone formation than TPS in in vivo study. DED surface also showed consistently good osseointegration performance throughout the early and late period of osseointegration. Collectively, these results show that the DED coating method is an innovative technology that can be utilized to make cementless joint implants.

Optimization of permeable membrane microchannel heat sinks for additive manufacturing

The design freedom brought by additive manufacturing (AM) can be leveraged in the design of microchannel heat sinks to improve their cooling performance. The permeable membrane microchannel (PMM) heat sink geometry was inspired by the ability of powder bed AM processes to fabricate partially porous metal parts having small internal flow features on the order of the powder size. The design routes coolant through a parallel array of thin permeable membranes arranged in a single-layer-manifold configuration. The permeable membranes provide effective heat exchange surfaces and the manifold configuration yields a low flow resistance across the PMM heat sink, all incorporated in a single layer by the use of AM. Past work has introduced the PMM heat sink concept, but the optimal geometric feature sizes were not explored or identified. The n current study is first to explore design optimization of the PMM heat sink to identify target feature sizes for AM fabrication, assessment of the conditions under which the PMM geometry outperforms other standard microchannel heat sink designs, and inspection of the ability of metal 3D printing process to produce the optimal features. To this end, a reduced-order PMM heat sink model is developed, a gradient-based-multi-objective optimization is performed to identify the optimal feature sizes for different coolants (water and 48/52 water/ethylene glycol mixture) at different flow rates (100–500 mL/min), footprint areas (49–900 mm2), and channel heights (0.5–2.5 mm). The optimization results are benchmarked against an optimized straight microchannel (SMC) heat sink design. Optimized PMM designs offer up to 68% lower thermal resistance at a set pressure drop compared to optimized SMC designs. A pair of SMC and PMM heat sinks optimized for the same operating conditions are 3D printed using direct-metal-laser-sintering (DMLS) of AlSi10Mg. X-ray microtomography is used to characterize the geometry of the 3D-printed parts. The model identifies that optimal membrane gap sizes on the order of ~ 10 s μm are required for the PMM to realize performance advantages compared to SMC heat sinks under the same operating conditions. The performance is predicted to be highly sensitive to this pore size, and even though DMLS is shown to produce parts with gaps as small as 26.7 µm, morphological deviations between the design and as-printed part are shown to lead to noticeable performance differences. Albeit excellent performance potential reinforced by this work, these findings call for further AM process development to ensure reliable, as-predicted PMM heat sinks to realize this potential.

Cold Strength and Failure of 3D-Printed Metals

Cold Strength and Failure of 3D-Printed Metals

Doughnut-Shaped and Top Hat Solar Laser Beams Numerical Analysis

Aside from the industry-standard Gaussian intensity profile, top hat and non-conventional laser beam shapes, such as doughnut-shaped profile, are ever more required. The top hat laser beam profile is well-known for uniformly irradiating the target material, significantly reducing the heat-affected zones, typical of Gaussian laser irradiation, whereas the doughnut-shaped laser beam has attracted much interest for its use in trapping particles at the nanoscale and improving mechanical performance during laser-based 3D metal printing. Solar-pumped lasers can be a cost-effective and more sustainable alternative to accomplish these useful laser beam distributions. The sunlight was collected and concentrated by six primary Fresnel lenses, six folding mirror collectors, further compressed with six secondary fused silica concentrators, and symmetrically distributed by six twisted light guides around a 5.5 mm diameter, 35 mm length Nd:YAG rod inside a cylindrical cavity. A top hat laser beam profile (Mx2 = 1.25, My2 = 1.00) was computed through both ZEMAX® and LASCAD® analysis, with 9.4 W/m2 TEM00 mode laser power collection and 0.99% solar-to-TEM00 mode power conversion efficiencies. By using a 5.8 mm laser rod diameter, a doughnut-shaped solar laser beam profile (Mx2 = 1.90, My2 = 1.00) was observed. The 9.8 W/m2 TEM00 mode laser power collection and 1.03% solar-to-TEM00 mode power conversion efficiencies were also attained, corresponding to an increase of 2.2 and 1.9 times, respectively, compared to the state-of-the-art experimental records. As far as we know, the first numerical simulation of doughnut-shaped and top hat solar laser beam profiles is reported here, significantly contributing to the understanding of the formation of such beam profiles.

Factors influencing the deposition of the inverse shape of 3D metal printing using electrochemical deposition

Factors influencing the deposition of the inverse shape of 3D metal printing using electrochemical deposition

Modeling and experiment on 3D position and size measurement of opaque droplet cloud with astigmatic dual-beam interferometric particle imaging (ADIPI)

This work investigates the astigmatic dual-beam interferometric particle imaging (ADIPI) to enable the measurement of the three-dimensional (3D) spatial position and particle size of spherical opaque particles. A general theoretical model based on the generalized Huygens-Fresnel integral and the ray transfer matrix model is established to characterize ADIPI signal, revealing the orientation and spacing of typical ADIPI fringes relating to the depth position and size. The model is applied to study the effects of several parameters, such as the focal length of cylindrical lens, the focal length of spherical lens and the distances between the elements in the optical system, on the relationship between the inclination angle of fringes and depth position by theoretical simulation. Experiments of ADIPI, incorporating dual-view digital inline holography (DIH), is performed to demonstrate the utility of ADIPI in the measurement of opaque spherical particles. Through the analysis of the general ADIPI signal based on two-dimensional Fourier transforms, 3D position and the particle size are obtained. The results of ADIPI, in both of the depth position and size measuring, exhibit a high degree of consistency with DIH's, given the average relative deviations of 5% in size measuring and 1% in depth position, respectively. As a new measurement approach, the ADIPI signal exists at arbitrary angle except the two laser beam axes, determining the flexibility of ADIPI configurations which facilitates its great prospect in opaque particles measurement, e.g., metal combustion, chip manufacturing, 3D metal printing.

A 3D Printed Ti6Al4V Alloy Uniaxial Capacitive Accelerometer

3D-printing techniques are attracting a lot of interest in the sensors community as promising fabrication processes that guarantee customizability at low costs. In this work, the first uniaxial Ti6Al4V alloy accelerometer is designed, fabricated through the Laser Powder Bed Fusion (L-PBF) technique and tested. Experimental tests under accelerations show good agreement with theoretical predictions. With a differential sensitivity of 184fF/g and relative low dimensions (features as low as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$500~\mu \text{m}$ </tex-math></inline-formula> ), the proposed accelerometer opens the path to a new class of 3D-printed metal sensors with high-performance, customizability and low-cost.

Optical detection of defects during laser metal deposition: Simulations and experiment

Laser metal deposition is a rapidly evolving method for additive manufacturing that combines high performance and simplified production routine. Quality of production depends on instrumental design and operational parameters that require constant control during the process. In this work, feasibility of using optical spectroscopy as a control method is studied via modeling and experimentally. A simplified thermal model is developed based on the time-dependent diffusion-conduction heat equation and geometrical light collection into detection optics. Intense light emitted by a laser-heated spot moving across a sample surface is collected and processed to yield the temperature and other temperature-related parameters. In a presence of surface defects the temperature field is distorted in a specific manner that depends on a shape and size of the defect. Optical signals produced by such the distorted temperature fields are simulated and verified experimentally using a 3D metal printer and a sample with artificially carved defects. Three quantities are tested as possible metrics for process monitoring: temperature, integral intensity, and correlation coefficient. The shapes of the simulated signals qualitatively agree with the experimental signals; this allows a cautious inference that optical spectroscopy is capable of detecting a defect and, possibly, predicting its character, e.g. inner or protruding.

Advanced Corrosion Protection of Additive Manufactured Light Metals by Creating Ceramic SurfaceThrough CERANOD® Plasma Electrolytical Oxidation Process

Lightweight structures produced by additive manufacturing (AM) technology such as the selective laser melting (SLM) process enable the fabrication of 3D structures with a high degree of freedom. A printed component can be tailored to have specific properties and render possible applications for industries such as the aerospace and automotive industries. Here, AlSi10Mg is one of the alloys that is currently used for SLM processes. Although the research with the aim improving the strength of AM aluminum alloy components is rapidly progressing, corrosion protection is scarcely addressed in this field. Plasma electrolytic oxidation (PEO) is an advanced electrolytical process for surface treatment of light metals such as aluminum, magnesium, and titanium. This process produces an oxide ceramic-like layer, which is extremely hard but also ductile, and significantly improves the corrosion and wear behavior. The aim of this study is to understand the corrosion behavior of 3D-printed AlSi10Mg alloy and to improve its corrosion resistance. For this reason, the properties of CERANOD®—PEO coating on an AlSi10Mg alloy produced by SLM were investigated on different AM surfaces, i.e., as-built, polished and stress relieved specimens. The corrosion performance of these surfaces was analyzed using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and long-term immersion tests. Moreover, the microstructure and morphology of the resulting coatings were characterized by SEM/EDS, taking into account the corrosive attacks. The results exhibited a high amount of localized corrosion in the case of the uncoated specimens, while the PEO process conducted on the aluminum AM surfaces led to enclosed homogeneous coatings by protecting the material’s pores, which are typically observed in AM process. Thereby, high corrosion protection could be achieved using PEO surfaces, suggesting that this technology is a promising candidate for unleashing the full potential of 3D light metal printing.

Three-dimensional metal printed orthodontic laboratory appliances

The orthodontic world is facing a new paradigm shift: digitalization. Alginate impressions and plaster models have largely been replaced by intraoral scans and three-dimensional (3D) resin printing. Today, 3D metal printing of metallic orthodontic appliances is at the forefront of the digitalization movement. The purpose of this article is to provide a clinical overview of this new technology.

열간 단조금형 이형제 분사용 매니폴드 적층 제조 설계 및 평가

In this study, design for additive manufacturing (DfAM) of release agent injection manifold for hot forging has been performed to achieve weight reduction and flow path optimization. The weight reduction of 53.5% was achieved, thereby enabling the application of stainless steel 316L, which has high strength and corrosion resistance. Lightweight manifolds using Al-Mg-10Si and SUS316L materials were fabricated by PBF-type metal 3D printer. The feasibility test showed that mold life was improved by 14% by solving residual release agent problem. In addition, the flow path optimization results suggested that the flow standard deviation of each outlet dropped sharply from 264 to 75 ㎤/s. This approach demonstrated that DfAM for release agent manifold could be applied to increase mold life and improve product quality and productivity for hot forging.

Effect of the Internal Shape of eDNA Filter Case made by the PBF method Metal 3D Printer on Water Sampling Performance

Effect of the Internal Shape of eDNA Filter Case made by the PBF method Metal 3D Printer on Water Sampling Performance

Submicron Metal 3D Printing by Ultrafast Laser Heating and Induced Ligand Transformation of Nanocrystals.

Currently, light-based three-dimensional (3D) printing with submicron features is mainly developed based on photosensitive polymers or inorganic-polymer composite materials. To eliminate polymer/organic additives, a strategy for direct 3D assembly and printing of metallic nanocrystals without additives is presented. Ultrafast laser with intensity in the range of 1 × 1010 to 1 × 1012 W/cm2 is used to nonequilibrium heat nanocrystals and induce ligand transformation, which triggers the spontaneous fusion and localized assembly of nanocrystals. The process is due to the operation of hot electrons as confirmed by a strong dependence of the printing rate on laser pulse duration varied in the range of electron-phonon relaxation time. Using the developed laser-induced ligand transformation (LILT) process, direct printing of 3D metallic structures at micro and submicron scales is demonstrated. Facile integration with other microscale additive manufacturing for printing 3D devices containing multiscale features is also demonstrated.

Present and Future Sustainability Development of 3D Metal Printing

Additive manufacturing (AM), also known as 3D printing is a relatively new concept and promising technology for industrial production. It is important to investigate the environmental impact of the AM process in light of the environmental critical situation of the Earth. The elimination of some costly prefabrication processes such as molding or post-fabrication stages such as machining and welding required in traditional manufacturing methods favor the AM process and provide beneficial economic advantages. Furthermore, the reduction of manufacturing steps contributes to environmental protection through fewer operations, less material, and energy consumption, and reduced transportation. This study is a review for the assessment of environmental impact and life cycle of some well-known AM technologies for manufacturing metallic parts and components. The fabrication of a pump impeller is simulated through a well-known metal production AM technology and casting process for direct comparison. Life Cycle Assessment (LCA) is applied to measure the environmental impact in five different stages of pump impeller lifetime with the two different fabrication processes. AM compared to casting has an environmental impact reduction potential of 15%, 20%, 65%, 20%, and 10% respectively in Global Warming Potential (GWP), Acidifications Potential (AP), Water Aquatic Eco-toxicity Potential (FAETP), Human Toxicity Potential (HTP), and Stratospheric Ozone Depletion (ODP). Using hydroelectricity and renewable electricity mitigate the environmental impact of the AM process in pre-manufacturing and manufacturing stages temporarily until the advancement of AM technology for consuming less energy. Recommendations for future research to enhance the environmental sustainability of the AM process is proposed as outcomes of this study.

Development of structured light 3D-scanner with high spatial resolution and its applications for additive manufacturing quality assurance

Digital three-dimensional (3D) scanning is a cutting-edge metrology method that can digitally reconstruct surface topography with high precision and accuracy. Such metrology can help traditional manufacturing processes evolve into a smart manufacturing paradigm, which can ensure product quality by automated sensing and control. However, due to limitations with the spatial resolution, scanning speed, and size of the focusing area, commercially available systems cannot be directly used for in-process monitoring in smart manufacturing. For example, a metal 3D printer requires a scanner with second-level sensing, micron-level spatial resolution, and a centimeter-scale scanning region. Among the 3D scanning technologies, structured light 3D scanning can meet the scanning speed criteria but not the spatial resolution and scanning region criteria. This work addresses these challenges by reducing the field of view of a structured light scanner system while increasing the image sensor pixel resolution. Improvements to spatial resolution and accuracy are achieved by establishing hardware selection criteria, integrating the proper hardware, designing a scale-appropriate calibration target, and developing noise reduction procedures during calibration. An additively manufactured Ti-6Al-4V part was used to validate the effectiveness of the proposed 3D scanner. The scanning result shows that both melt pool geometry and overall shape can be clearly captured. In the end, the scanning accuracies of the proposed scanner and a professional-grade commercial scanner are validated with a nanometer-level accuracy white light interferometer using high-density point cloud data. Compared to the commercial scanner, the proposed scanner improves the spatial resolution from 48 to 5 μm and the accuracy from 108.5 to 0.5 μm. Compared to the white light interferometer, the proposed scanner improves the scanning and processing speed from 2 to 20 s.

First 3D Printed IH-Type Linac Structure - Proof-of-Concept for Additive Manufacturing of Linac rf Cavities

Additive manufacturing (or printing) has become a powerful tool for rapid prototyping and manufacturing of complex geometries. As technology is evolving, the quality and accuracy of parts manufactured this way is ever improving. Especially interesting for the world of particle accelerators is the process of 3D printing of stainless steel (and copper) parts. We present the first fully functional IH-type drift tube structure manufactured by metal 3D printing. A 433 MHz prototype cavity has been constructed to act as a proof-of-concept for the technology. The cavity is designed to be UHV capable and includes cooling channels reaching into the stems of the DTL structure. We present the first experimental results for this prototype.

Relationship between 316L steel powder characteristics and residual stress in additive manufactured builds

This investigation involved cube samples created by an Additive Manufacturing (AM) process. Four commercially available AISI 316L powders with a particle size range of 50-150 μm were used to produce four cube-shapes samples using Direct Energy Deposition (DED) in the industrial metal 3D printer InssTek MX-600. The contour method (CM), a destructive stress relaxation method, was used to determine the residual stress distribution on the cross-section. The results illustrate the impact of the powders on residual stress distribution after DED additive process.

A review of Wire Arc Additive Manufacturing (WAAM) of Aluminium Composite, Process, Classification, Advantages, Challenges, and Application

Wire-arc additive manufacturing (WAAM) is a common metal 3D printing technique that offers several benefits, including the high rate of deposition, cheap price, and efficacy for complex parts. Even though (WAAM) has demonstrated its ability to meet the demands of manufacture components on medium-to-large size made of (Al) for the automotive and other related industries, WAAM cannot currently use as a complete production procedure due to practical issues such as mechanical properties that aren’t matched and the presence of significant residual stresses. the AM technologies offer promising new benefits with the MMCs as a solution for some challenges. This article reviews the MMCs Mixing technique and their critical issues, AM classification, WAAM process with advantages and challenges. also reviews WAAM of some AMCs with different reinforcements and power sources. The results of the study of the influence of reinforcement particles on the structure showed that they were changed grains structure from the columnar dendrite to equiaxial dendrites after the solidification and improves hardness.

Features of Heat Treatment the Ti-6Al-4V GTD Blades Manufactured by DLD Additive Technology.

Additive manufacturing of titanium alloys is one of the fastest growing areas of 3D metal printing. The use of AM methods for parts production in the aviation industry is especially promising. During the deposition of products with differently sized cross-sections, the thermal history changes, which leads to non-uniformity of the structure and properties. Such heterogeneity can lead to failure of the product during operation. The structure of deposited parts, depending on the thermal cycle, may consist of α’, α + α’ + β’, and α + β in different ratios. This problem can be solved by using heat treatment (HT). This paper presents research aimed towards the determination of optimal heat treatment parameters that allows the reception of the uniform formation of properties in the after-treatment state, regardless of the initial structure and properties, using the example of a deposited Ti-6Al-4V gas turbine blade.

Acoustic behaviour of 3D printed titanium perforated panels

Titanium alloys such as Ti6Al4V is amongst the most widely studied metallic materials in the broad context of metal 3D printing. Although the mechanical performances are well understood, the acoustic performance of 3D printed Ti6Al4V, and Ti6Al4V ELI (Extra Low Interstitial) has received limited attention in the literature. As such, this study investigates the normal incidence sound absorption coefficient (α) and Sound Transmission Loss (STL) of both Ti6Al4V and Ti6Al4V ELI samples manufactured using Selective Laser Melting (SLM). The influence of material thickness on acoustic responses and the potential of developing Ti6Al4V micro-perforated panels (MPP) at 400–1600 Hz is also explored. The sound absorption of three aesthetic perforations printed using Ti6Al4V and the influence of a porous back layer was also investigated. The experimental measurements were carried out using an impedance tube following ISO10534-2. The result of the study establishes that 3D printed non-circular perforations featuring porous back-layer can exhibit improved sound absorption coefficient.