Journal articles on the topic 'Material extrusion (ME)'
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1
Hsiang Loh, Giselle, Eujin Pei, Joamin Gonzalez-Gutierrez, and Mario Monzón. "An Overview of Material Extrusion Troubleshooting." Applied Sciences 10, no. 14 (July 11, 2020): 4776. http://dx.doi.org/10.3390/app10144776.
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Material extrusion (ME) systems offer end-users with a more affordable and accessible additive manufacturing (AM) technology compared to other processes in the market. ME is often used to quickly produce low-cost prototyping with the freedom of scalability where parts can be produced in different geometries, quantities and sizes. As the use of desktop ME machines has gained widespread adoption, this review paper discusses the key design strategies and considerations to produce high quality ME parts, as well as providing actional advice to aid end-users in quickly identifying and efficiently troubleshooting issues since current information is often fragmented and incomplete. The systemic issues and solutions concerning desktop ME processes discussed are not machine-specific, covering categories according to printer-associated, deposition-associated and print quality problems. The findings show that the majority of issues are associated with incorrect printer calibration and parameters, hardware, material, Computer Aided Design (CAD) model and/or slicing settings. A chart for an overview of ME troubleshooting is presented allowing designers and engineers to straightforwardly determine the possible contributing factors to a particular problem.
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Jiang, Shijie, Ke Hu, Yang Zhan, Chunyu Zhao, and Xiaopeng Li. "Theoretical and Experimental Investigation on the 3D Surface Roughness of Material Extrusion Additive Manufacturing Products." Polymers 14, no. 2 (January 11, 2022): 293. http://dx.doi.org/10.3390/polym14020293.
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Material extrusion (ME), one of the most widely used additive manufacturing technique, has the advantages of freedom of design, wide range of raw materials, strong ability to manufacture complex products, etc. However, ME products have obvious surface defects due to the layer-by-layer manufacturing characteristics. To reveal the generation mechanism, the three-dimensional surface roughness (3DSR) of ME products was investigated theoretically and experimentally. Based on the forming process of bonding neck, the 3DSR theoretical model in two different directions (vertical and parallel to the fiber direction) was established respectively. The preparation of ME samples was then completed and a series of experimental tests were performed to determine their surface roughness with the laser microscope. Through the comparison between theoretical and experimental results, the proposed model was validated. In addition, sensitivity analysis is implemented onto the proposed model, investigating how layer thickness, extrusion temperature, and extrusion width influence the samples’ surface roughness. This study provides theoretical basis and technical insight into improving the surface quality of ME products.
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Chua, Bih-Lii, Sun-Ho Baek, Keun Park, and Dong-Gyu Ahn. "Numerical Investigation of Deposition Characteristics of PLA on an ABS Plate Using a Material Extrusion Process." Materials 14, no. 12 (June 19, 2021): 3404. http://dx.doi.org/10.3390/ma14123404.
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Three-dimensional prototypes and final products are commonly fabricated using the material extrusion (ME) process in additive manufacturing applications. However, these prototypes and products are limited to a single material using the ME process due to technical challenges. Deposition of plastic on another dissimilar plastic substrate requires proper control of printing temperature during an ME process due to differences in melting temperatures of dissimilar plastics. In this paper, deposition of PLA filament on an ABS substrate during an ME process is investigated using finite element analysis. A heat transfer finite element (FE) model for the extrusion process is proposed to estimate the parameters of the ME machine for the formulation of a heat flux model. The effects of printing temperature and the stand-off distance on temperature distributions are investigated using the proposed FE model for the extrusion process. The heat flux model is implemented in a proposed heat transfer FE model of single bead deposition of PLA on an ABS plate. From this FE model of deposition, temperature histories during the ME deposition process are estimated. The results of temperature histories are compared with experiments. Using the calibrated FE model, a proper heating temperature of ABS for deposition of PLA is evaluated.
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Carminati, Mattia, Mariangela Quarto, Gianluca D’Urso, Claudio Giardini, and Giancarlo Maccarini. "Mechanical Characterization of AISI 316L Samples Printed Using Material Extrusion." Applied Sciences 12, no. 3 (January 28, 2022): 1433. http://dx.doi.org/10.3390/app12031433.
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The main additive manufacturing (AM) methods to produce metal components are laser powder bed fusion and directed energy deposition, which are energy-intensive, time-consuming, and require high investment costs. An economical alternative is based on a new feedstock comprising a homogenous mixture of sinterable metal powders and a multi-component binder system. This feedstock enables the creation of metal components printed using the material extrusion (ME) technique. In this study, mechanical characterization of AISI 316L samples is conducted to identify the mechanical properties of parts printed using the metal ME process. The test results indicate an average maximum tensile stress of 426.6 ± 23.7 MPa and an elongation at break of 36%. Both the tensile and compressive yield stresses are approximately 150 MPa, demonstrating a symmetric response to the two opposite types of uniaxial loads. Rockwell B and Vickers hardness tests confirm the uniform behavior of the tested material. An X-ray diffraction analysis is conducted to assess the crystallographic structure of the ME 316L samples compared to that of the monolithic material. According to our study results, metal ME seems to be a promising technology to produce non-critical metallic parts that require good mechanical properties, good corrosion resistance, and complex shapes such as chemical tanks, heat exchangers, and medical instruments.
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Jiang, Shijie, Yinfang Shi, Yannick Siyajeu, Ming Zhan, Chunyu Zhao, and Changyou Li. "Effect of Processing Parameters on the Dynamic Characteristic of Material Extrusion Additive Manufacturing Plates." Applied Sciences 9, no. 24 (December 6, 2019): 5345. http://dx.doi.org/10.3390/app9245345.
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Material extrusion (ME), an additive manufacturing technique, can fabricate parts almost without geometrical limitations. With the growing application of ME parts, especially in actual working conditions, the dynamic characteristics are needed to be studied to accurately determine their reliability. This study provides an experimental validation of the theoretical model for predicting the dynamic characteristics of ME plates fabricated with three different key processing parameters, i.e., extrusion width, layer height and build direction. The model is set up based on the bidirectional beam function combination method, and a series of experimental tests are performed. It is found that different processing parameters result in the material properties of the samples to vary, thus leading to different dynamic characteristics. Through the comparison between predictions and measurements, it is shown that the influencing trend of the processing parameters is predicted precisely. The theoretical model gives reliable predictions in dynamic characteristics of ME plates. The natural frequency discrepancy is below 13.4%, and the predicted mode shapes are the same as the measured ones. This present work provides theoretical basis and technical support for further research in improving the dynamic performance of ME products, and helps extend the applications of this technique.
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Revilla-Leon, Marta, Marina Olea-Vielba, Ana Esteso-Díaz, Iñaki Martinez-Klemm, Jose Manuel Reuss Rodriguez-Vilaboa, and Mutlu Özcan. "New fabrication method using additive manufacturing technologies for the pattern of pressed lithium disilicate onlay restorations." Brazilian Dental Science 20, no. 4 (December 20, 2017): 149. http://dx.doi.org/10.14295/bds.2017.v20i4.1364.
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<p>There are 7 categories for the additive manufacturing (AM) technologies and a wide variety of materials that can be used to build a computer aided designed (CAD) 3-Dimensional (3D) object. The present article reviews the main AM processes for polymers for dental applications: stereolithography (SLA), direct light processing (DLP), material jetting (MJ) and material extrusion (ME). The manufacturing process, accuracy and precision of these methods will be reviewed, as well as, their prosthodontic applications.</p><p> </p><p><strong>Keywords: </strong>3D printing; Additive manufacturing technologies; Direct light processing; Fused deposition modelling; Material extrusion; Material jetting; Multijet printing; Prosthodontics; Stereolitography.</p>
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Kim, Hyungjung, Hyunsu Lee, Ji-Soo Kim, and Sung-Hoon Ahn. "Image-based failure detection for material extrusion process using a convolutional neural network." International Journal of Advanced Manufacturing Technology 111, no. 5-6 (October 9, 2020): 1291–302. http://dx.doi.org/10.1007/s00170-020-06201-0.
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Abstract The material extrusion (ME) process is one of the most widely used 3D printing processes, especially considering its use of inexpensive materials. However, the error known as the “spaghetti-shape error,” related to filament tangling, is a common problem associated with the ME process. Once occurring, this issue, which consumes both time and materials, requires a restart of the entire process. In order to prevent this, the user must constantly monitor the process. In this research, a failure detection method which uses a webcam and deep learning is developed for the ME process. The webcam captures images and then analyzes them by machine learning based on a convolutional neural network (CNN), showing outstanding performance in both image classification and the recognition of objects. Sample images were trained based on a modified Visual Geometry Group Network (VGGNet) model and the trained model was evaluated, resulting in 97% accuracy. The pre-trained model was tested on a 3D printer monitoring system for its ability to recognize the “spaghetti-shape-error” and was able to detect 96% of abnormal deposition processes. The proposed method can analyze the ME process in real time and informs the user or halts the process when abnormal printing is detected.
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Watschke, Hagen, Lennart Waalkes, Christian Schumacher, and Thomas Vietor. "Development of Novel Test Specimens for Characterization of Multi-Material Parts Manufactured by Material Extrusion." Applied Sciences 8, no. 8 (July 25, 2018): 1220. http://dx.doi.org/10.3390/app8081220.
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Multi-material additive manufacturing (AM) offers new design opportunities for functional integration and opens new possibilities in innovative part design, for example, regarding the integration of damping or conductive structures. However, there are no standardized test methods, and thus test specimens that provide information about the bonding quality of two materials printed together. As a result, a consideration of these new design potentials in conceptual design is hardly possible. As material extrusion (ME) allows easily combination of multiple polymeric materials in one part, it is chosen as an AM technique for this contribution. Based on a literature review of commonly used standards for polymer testing, novel test specimens are developed for the characterization of the bonding quality of two ME standard materials printed together. The proposed specimen geometries are manufactured without a variation of process parameters. The load types investigated in the course of this study were selected as examples and are tensile, lap-shear, and compression-shear. The conducted tests show that the proposed test specimens enable a quantification of the bonding quality in the material transition. Moreover, by analyzing the fracture pattern of the interface zone, influencing factors that probably affect the interface strength are identified, which can be further used for its optimization.
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Galantucci, Luigi Maria, Alessandro Pellegrini, Maria Grazia Guerra, and Fulvio Lavecchia. "3D Printing of parts using metal extrusion: an overview of shaping debinding and sintering technology." Advanced Technologies & Materials 47, no. 1 (June 15, 2022): 25–32. http://dx.doi.org/10.24867/atm-2022-1-005.
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Additive Manufacturing (AM) is the fabrication of real three-dimensional objects from plastics and metals by adding material, layer by layer. One of the most common AM processes is the Material Extrusion (ME) based on different approaches: plunger, filament and screw. Material Extrusion technologies of metal-polymer composites is expanding and it mainly uses the filament or plunger-based approaches. The feedstock used is a mixture of metal powder (from 55 vol% to about 80 vol%) dispersed in a thermoplastic matrix, as the Metal Injection Molding (MIM) materials. The process consists of three steps: shaping, debinding and sintering. The first step provides the extrusion of filament to realize a primary piece called “green part”; subsequent steps, debinding and sintering, allow to obtain a full metal part by dissolving the polymeric binder. The latter can be carried out using solvents, heat and the combination of them. The interest toward this technology is driven by the possibility to replace other Metal AM technologies, such as Selective Laser Melting or Direct Energy Deposition, in sectors like rapid-tooling or mass production, with several benefits: simplicity, safety to use and saving material and energy. The aim of this keynote is to provide a general overview of the main metal ME technologies considering the more technical aspects such as process methodologies, 3D printing strategy, process parameters, materials and possible applications for the manufacturing of samples on a 3D consumer printer.
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Tateno, Toshitake, Akira Kakuta, Hayate Ogo, and Takaya Kimoto. "Ultrasonic Vibration-Assisted Extrusion of Metal Powder Suspension for Additive Manufacturing." International Journal of Automation Technology 12, no. 5 (September 5, 2018): 775–83. http://dx.doi.org/10.20965/ijat.2018.p0775.
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Additive manufacturing (AM) using metal materials can be used to manufacture metal parts with complex shapes that are difficult to manufacture with subtractive processing. Recently, numerous commercial AM machines for metallic materials have been developed. The primary types of AM using metallic materials are powder bed fusion or direct energy deposition. Other types using metallic materials have not been adequately studied. In this study, the use of the material extrusion (ME) type of AM is investigated. The aim is to use metallic materials not only for fabricating metal parts but also for adding various properties to base materials, e.g., electric conductivity, thermal conductivity, weight, strength, and color of plastics. ME is appropriate for use with various materials by mixing different types of filler. However, there is a problem in that the high density of metal fillers generates unstable extrusion. Therefore, ultrasonic vibration was used for assisting extrusion. A prototype system was developed using an extrusion nozzle vibrated by an ultrasonic homogenizer. The experimental results showed that the ultrasonic vibration allows materials to be extruded smoothly. Three dimensional (3D) shapes could be built by multi-layer deposition with a thixotropic polymer containing a highly concentrated steel powder. As one application, a 3D-shaped object was fabricated as a sintered object. After the vibration effect in the extrusion process of steel powder and clay was confirmed, a 3D object built by the proposed method was sintered through a baking process.
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Zhang, Zhicheng, James Femi-Oyetoro, Ismail Fidan, Muhammad Ismail, and Michael Allen. "Prediction of Dimensional Changes of Low-Cost Metal Material Extrusion Fabricated Parts Using Machine Learning Techniques." Metals 11, no. 5 (April 23, 2021): 690. http://dx.doi.org/10.3390/met11050690.
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Additive manufacturing (AM) is a layer-by-layer manufacturing process. However, its broad adoption is still hindered by limited material options, different fabrication defects, and inconsistent part quality. Material extrusion (ME) is one of the most widely used AM technologies, and, hence, is adopted in this research. Low-cost metal ME is a new AM technology used to fabricate metal composite parts using sintered metal infused filament material. Since the involved materials and process are relatively new, there is a need to investigate the dimensional accuracy of ME fabricated metal parts for real-world applications. Each step of the manufacturing process, from the material extrusion to sintering, might significantly affect the dimensional accuracy. This research provides a comprehensive analysis of dimensional changes of metal samples fabricated by the ME and sintering process, using statistical and machine learning algorithms. Machine learning (ML) methods can be used to assist researchers in sophisticated pre-manufacturing planning and product quality assessment and control. This study compares linear regression to neural networks in assessing and predicting the dimensional changes of ME-made components after 3D printing and sintering process. In this research, the ML algorithms present a significantly high coefficient of determination (i.e., 0.999) and a very low mean square error (i.e., 0.0000878). The prediction outcomes using a neural network approach have the smallest mean square error among all ML algorithms and it has quite small p-values. So, in this research, the neural network algorithm has the highest accuracy. The findings of this study can help researchers and engineers to predict the dimensional variations and optimize the printing and sintering process parameters to obtain high quality metal parts fabricated by the low-cost ME process.
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Zhang, Zhicheng, and Ismail Fidan. "Machine Learning-Based Void Percentage Analysis of Components Fabricated with the Low-Cost Metal Material Extrusion Process." Materials 15, no. 12 (June 17, 2022): 4292. http://dx.doi.org/10.3390/ma15124292.
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Additive manufacturing (AM) is a widely used layer-by-layer manufacturing process. Material extrusion (ME) is one of the most popular AM techniques. Lately, low-cost metal material extrusion (LCMME) technology is developed to perform metal ME to produce metallic parts with the ME technology. This technique is used to fabricate metallic parts after sintering the metal infused additively manufactured parts. Both AM and sintering process parameters will affect the quality of the final parts. It is evident that the sintered parts do not have the same mechanical properties as the pure metal parts fabricated by the traditional manufacturing processes. In this research, several machine learning algorithms are used to predict the size of the internal voids of the final parts based on the collected data. Additionally, the results show that the neural network (NN) is more accurate than the support vector regression (SVR) on prediction.
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Jiang, Shijie, Pifeng Chen, Yang Zhan, and Chunyu Zhao. "Theoretical and Computational Analysis on the Melt Flow Behavior of Polylactic Acid in Material Extrusion Additive Manufacturing under Vibration Field." Applied Sciences 10, no. 11 (May 29, 2020): 3801. http://dx.doi.org/10.3390/app10113801.
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Material extrusion (ME), an extrusion-based rapid prototyping technique, has been extensively studied to manufacture final functional products, whose forming quality is significantly influenced by the melt flow behavior (MFB) inside the extrusion liquefier. Applied vibration has a great potential to improve the MFB, and thereby promote the forming quality of the built product. To reveal the mechanism, a dynamic model of the melt flow behavior (DMMFB) is established based on fluid dynamics, Tanner nonlinear constitutive equation and Newton’s power law equation. The MFB, i.e., pressure drop, shear stress and apparent viscosity, is investigated without and with different vibration applied. The corresponding finite element analysis (FEA) is then carried out. From the comparison between DMMFB and FEA results, it is concluded that the proposed model is reliable. When vibration is applied onto the extrusion liquefier, the time-domain MFB will change periodically. Its effective value decreases significantly, and further decreases with the increase of vibration frequency or amplitude. This paper provides the theoretical basis to improve the MFB by applied vibration, and thereby to enhance the forming quality of ME products.
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Garcia Rosales, Carlos Alejandro, Hoejin Kim, Mario F. Garcia Duarte, Luis Chavez, Mariana Castañeda, Tzu-Liang Bill Tseng, and Yirong Lin. "Characterization of shape memory polymer parts fabricated using material extrusion 3D printing technique." Rapid Prototyping Journal 25, no. 2 (March 4, 2019): 322–31. http://dx.doi.org/10.1108/rpj-08-2017-0157.
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Purpose Shape memory polymer (SMP) is capable of recovering its original shape from a high degree of deformation by applying an external stimulus such as thermal energy. This research presents an integration of two commercial SMP materials (DiAPLEX and Tecoflex) and a material extrusion (ME) printer to fabricate SMP parts and specimens. The material properties such as Young’s modulus of the specimens was examined as a process output. Furthermore, stress-strain curve, strain recovery, instant shape-fixity ratio, long-term shape-fixity ratio and recovery ratio of SMP specimens during a thermo-mechanical cycle were investigated. Design/methodology/approach The ME fabrication settings for the SMP specimens were defined by implementing a design of experiments with temperature, velocity and layer height as process variables. Findings It was found, according to main effect and iteration plots, that fabrication parameters have an impact on Young’s modulus and exist minimum iteration among variables. In addition, Young’s modulus variation of DiAPLEX and Tecoflex specimens was mostly caused by velocity and layer height parameters, respectively. Moreover, results showed that SMP specimens were able to recover high levels of deformation. Originality/value This paper is a reference for process control and for rheological properties of SMP parts produced by ME fabrication process.
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Verbeeten, Wilco M. H., Miriam Lorenzo-Bañuelos, Rubén Saiz-Ortiz, and Rodrigo González. "Strain-rate-dependent properties of short carbon fiber-reinforced acrylonitrile-butadiene-styrene using material extrusion additive manufacturing." Rapid Prototyping Journal 26, no. 10 (October 26, 2020): 1701–12. http://dx.doi.org/10.1108/rpj-12-2019-0317.
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Purpose The purpose of the present paper is to quantify and analyze the strain-rate dependence of the yield stress for both unfilled acrylonitrile-butadiene-styrene (ABS) and short carbon fiber-reinforced ABS (CF-ABS) materials, fabricated via material extrusion additive manufacturing (ME-AM). Two distinct and opposite infill orientation angles were used to attain anisotropy effects. Design/methodology/approach Tensile test samples were printed with two different infill orientation angles. Uniaxial tensile tests were performed at five different constant linear strain rates. Apparent densities were measured to compensate for the voided structure. Scanning electron microscope fractography images were analyzed. An Eyring-type flow rule was evaluated for predicting the strain-rate-dependent yield stress. Findings Anisotropy was detected not only for the yield stresses but also for its strain-rate dependence. The short carbon fiber-filled material exhibited higher anisotropy than neat ABS material using the same ME-AM processing parameters. It seems that fiber and molecular orientation influence the strain-rate dependence. The Eyring-type flow rule can adequately describe the yield kinetics of ME-AM components, showing thermorheologically simple behavior. Originality/value A polymer’s viscoelastic behavior is paramount to be able to predict a component’s ultimate failure behavior. The results in this manuscript are important initial findings that can help to further develop predictive numerical tools for ME-AM technology. This is especially relevant because of the inherent anisotropy that ME-AM polymer components show. Furthermore, short carbon fiber-filled ABS enhanced anisotropy effects during ME-AM, which have not been measured previously.
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Jimbo, Koki, and Toshitake Tateno. "Shape Contraction in Sintering of 3D Objects Fabricated via Metal Material Extrusion in Additive Manufacturing." International Journal of Automation Technology 13, no. 3 (May 5, 2019): 354–60. http://dx.doi.org/10.20965/ijat.2019.p0354.
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Additive manufacturing (AM) using metal materials (metal AM) is useful in the fabrication of metal parts with complex shapes, which are difficult to manufacture via subtractive processing. Metal AM is employed in the manufacture of final products as well as in prototyping. Recently, certain metal-AM machines have been commercialized. Powder-bed fusion and direct energy deposition are the main types of metal AM; they require the use of a high-power laser or electron beam and most of them are highly expensive. On the other hand, AM machines of the material-extrusion (ME) type can fabricate metal parts at a low cost. ME is the method of extruding materials from a nozzle and fabricating thin layers. By mixing a metal filler with a base material, it is possible to impart various mechanical properties to the extruded material, such as electrical or thermal conductivity. If the extruded material is baked in a furnace after fabrication, the object can be sintered. During the sintering process, the fabricated objects always shrink and dimensional errors occur. One of the reasons for the shrinkage is that voids are generated inside the object after the degreasing process and collapse during the sintering process. Because the void is generated as a space by replacing a binder that becomes vaporized during the degreasing process, the shrinkage may be controlled by decreasing the content in polymers. In this study, the effect of the metal filler density on the shrinkage in shape was investigated through experiments using two types of metal ME AM. One type is the fused filament fabrication (FFF), in which a material that consists of a metal filler and fused plastics is extruded; the other type is the ultrasonic vibration-assisted ME (UVAME) device, in which a metal powder suspension with a small amount of thickening polymer is extruded. In the latter method, materials with an extremely high density in metal fillers were used; it was considered that degreasing was not required. Two types of specimens were fabricated using AM devices; they were then degreased and sintered. The resulting shapes of the objects were measured with a 3D scanner and were compared. The experimental results showed that the shrinkage of the material with a high density of metal fillers was less than that of the material with a low density of metal fillers.
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Kaill, Nathaniel, Patrick Pradel, Guy Bingham, and R. Ian Campbell. "Using Carbon-fibre Reinforcement with a 5-axis Material Extrusion System." MATEC Web of Conferences 299 (2019): 06002. http://dx.doi.org/10.1051/matecconf/201929906002.
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One of the main limitations of material extrusion (ME) components is their anisotropic mechanical behaviour, mainly due to the poor bonding between layers. 5-axis ME has the capability to orientate theprint layers in line with loading conditions, in order to limit the effect of poor inter-laminar bonding. Previous work has demonstrated how aligning deposited material in the same direction as the dominant stresses can improve a part’s mechanical performance. When fibre-reinforcement is added to theseoriented layers, the stiffness and strength of parts should increase further. This paper presents a comparison between 5-axis parts that were printed in pure poly-lactic acid (PLA) and in carbon-fibrereinforced (CFR) PLA. Sets of dome-shaped components were built using several different build strategies and tested for compressive stiffness and strength. The results were rather mixed but did show a marked improvement in compressive strength under certain conditions. Further work is required to understand one of the failure mechanisms that was seen and to overcome some of the limitations of the 5-axis machine currently being used. The work was undertaken to support the Directional Composites through Innovative Manufacturing (DiCoMI) project, funded by the European Commission.
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Garcia Rosales, Carlos Alejandro, Hoejin Kim, Mario F. Garcia Duarte, Luis Chavez, Tzu-Liang Bill Tseng, and Yirong Lin. "Toughness-based recovery efficiency of shape memory parts fabricated using material extrusion 3D printing technique." Rapid Prototyping Journal 25, no. 1 (January 7, 2019): 30–37. http://dx.doi.org/10.1108/rpj-09-2017-0188.
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Purpose Shape memory polymers (SMPs) are classified as smart materials owing to their inherent stimulus-induced response. SMPs are capable of recovering partially or totally to its original shape after a high degree of deformation by external stimulus. The most used stimuli are thermal, light, magnetic field and electricity. This research aims to characterize the toughness property of thermo-responsive SMP specimens fabricated by the material extrusion (ME) process and to investigate the impact of ME parameters on specimen maximum load and load-displacement curves. Moreover, to investigate the recovery efficiency based on the initial and post toughness generated by the compact tension test. Design/methodology/approach A design of experiments with three parameters (temperature, velocity and layer height) defined the ME settings to fabricate the specimens. The ME raster orientation factor was also evaluated separately. In addition, one more specimen group assisted by a clamp during the recovery process was compared with a specimen control group. After fabrication, specimens were submitted to a thermo-mechanical cycle that encompasses a compact tension test and a thermo-recovery process. Comparison studies of load-displacement, toughness and recovery efficiency of the specimens were carried out to determine the optimized fabrication parameters. Findings It was found that ME parameters and raster orientation impacted the test results. Samples with the clamp support during recovery returned a higher toughness than samples without support. Finally, results showed that the shape memory effect can contribute with up to 43 per cent recovery efficiency in a first recovery and up to 23 per cent in a second recovery of damaged specimens. Originality/value This paper is a reference for toughness and recovery properties of SMP parts produced by the ME fabrication process.
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Jiang, Shijie, Mingyu Sun, Yang Zhan, Hui Li, and Wei Sun. "A dynamic model of laminated material extrusion additive manufacturing plate with the property of orthogonal anisotropy." Rapid Prototyping Journal 27, no. 4 (May 21, 2021): 785–96. http://dx.doi.org/10.1108/rpj-04-2020-0075.
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Purpose The purpose of this study is to set up a dynamic model of material extrusion (ME) additive manufacturing plates for the prediction of their dynamic behavior (i.e. dynamic inherent characteristic, resonant response and damping) and also carry out its experimental validation and sensitivity analysis. Design/methodology/approach Based on the classical laminated plate theory, a dynamic model is established using the orthogonal polynomials method, taking into account the effect of lamination and orthogonal anisotropy. The dynamic inherent characteristics of the ME plate are worked out by Ritz method. The frequency-domain dynamic equations are then derived to solve the plates’ resonant responses, with which the damping ratio is figured out according to the half-power bandwidth method. Subsequently, a series of experimental tests are performed on the ME samples to obtain the measured data. Findings It is shown that the predictions and measurements in terms of dynamic behavior are in good agreement, validating the accuracy of the developed model. In addition, sensitivity analysis shows that increasing the elastic modulus or Poisson’s ratio will increase the corresponding natural frequency of the ME plate but decrease the resonant response. When the density is increased, both the natural frequency and resonant response will be decreased. Research limitations/implications Future research can be focused on using the proposed model to investigate the effect of processing parameters on the ME parts’ dynamic behavior. Practical implications This study shows theoretical basis and technical insight into improving the forming quality and reliability of the ME parts. Originality/value A novel reliable dynamic model is set up to provide theoretical basis and principle to reveal the physical phenomena and mechanism of ME parts.
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Kubalak, Joseph R., Alfred L. Wicks, and Christopher B. Williams. "Exploring multi-axis material extrusion additive manufacturing for improving mechanical properties of printed parts." Rapid Prototyping Journal 25, no. 2 (March 4, 2019): 356–62. http://dx.doi.org/10.1108/rpj-02-2018-0035.
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Purpose Material extrusion (ME) suffers from anisotropic mechanical properties that stem from the three degree of freedom (DoF) toolpaths used for deposition. The formation of each layer is restricted to the XY-plane, which produces poorly bonded layer interfaces along the build direction. Multi-axis ME affords the opportunity to change the layering and deposition directions locally throughout a part, which could improve a part’s overall mechanical performance. The purpose of this paper is to evaluate the effects of changing the layering and deposition directions on the tensile mechanical properties of parts printed via multi-axis ME. Design/methodology/approach A multi-axis toolpath generation algorithm is presented and implemented on a 6-DoF robotic arm ME system to fabricate tensile specimens at different global orientations. Specifically, acrylonitrile butadiene styrene (ABS) tensile specimens are printed at various inclination angles using the multi-axis technique; the resulting tensile strengths of the multi-axis specimens are compared to similarly oriented specimens printed using a traditional 3-DoF method. Findings The multi-axis specimens had similar performances regardless of orientation and were equivalent to the 3-DoF specimens printed in the XYZ orientation (i.e. flat on the bed with roads aligned to the loading condition). This similarity is attributed to those sets of specimens having the same degree of road alignment. Practical implications Parts with out-of-plane loads currently require design compromises (e.g. additional material in critical areas). Multi-axis deposition strategies could enable local changes in layering and deposition directions to more optimally orient roads in critical areas of the part. Originality/value Though multi-axis ME systems have been demonstrated in literature, no prior work has been done to determine the effects of the deposition angle on the resulting mechanical properties. This work demonstrates that identical mechanical properties can be obtained irrespective of the build direction through multi-axis deposition. For ABS, the yield tensile strength of vertically oriented tensile bars was improved by 153 per cent using multi-axis deposition as compared to geometrically similar samples fabricated via 3-DoF deposition.
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Verbeeten, Wilco M. H., Rob J. Arnold-Bik, and Miriam Lorenzo-Bañuelos. "Print Velocity Effects on Strain-Rate Sensitivity of Acrylonitrile-Butadiene-Styrene Using Material Extrusion Additive Manufacturing." Polymers 13, no. 1 (January 1, 2021): 149. http://dx.doi.org/10.3390/polym13010149.
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The strain-rate sensitivity of the yield stress for Acrylonitrile-Butadiene-Styrene (ABS) tensile samples processed via material extrusion additive manufacturing (ME-AM) was investigated. Such specimens show molecular orientation and interstitial voids that affect the mechanical properties. Apparent densities were measured to compensate for the interstitial voids. Three different printing speeds were used to generate ME-AM tensile test samples with different molecular orientation. Printing velocities influenced molecular orientation and stretch, as determined from thermal shrinkage measurements. Likewise, infill velocity affected the strain-rate dependence of the yield stress. The ABS material manifests thermorheollogically simple behavior that can correctly be described by an Eyring flow rule. The changing activation volume, as a result of a varying print velocity, scales linearly with the molecular orientation, as captured in an estimated processing-induced pre-strain. Therefore, it is suggested that ME-AM processed ABS shows a deformation-dependent activation volume. This paper can be seen as initial work that can help to improve quantitative predictive numerical tools for ME-AM, taking into account the effects that the processing step has on the mechanical properties.
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Hohenstein, Steffen, Georg Bergweiler, Gerret Lukas, Viktoria Krömer, and Tobias Otten. "Decision basis for multi-directional path planning for post-processing reduction in material extrusion." Production Engineering 15, no. 3-4 (March 19, 2021): 457–66. http://dx.doi.org/10.1007/s11740-021-01018-6.
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AbstractReducing support structures in Material Extrusion (ME) of Additive Manufacturing enables lowered post-processing efforts and enhanced use in industrial applications. This study provides a decision basis for multi-directional path planning strategy to print parts on multi-axis printers without the use of support structures. Research solutions for different limitations of ME systems are examined. The combination of Flat and Curved Layer Slicing, Adaptive Slicing, Load-Capable Path Planning and Multi-Axis Slicing enables printing a multi-directional demonstrator part. The part’s build structure consists of form elements (features) with varying build directions depending on the transition areas between them. A proof-of-concept on a three-axis printer shows the ability of a multi-directional printing method for multi-axis printer systems. Interfaces between features require print parameter adjustment to obtain the desired mechanical properties. Tensile tests are performed to evaluate the mechanical load capacity at connecting areas between features of standard specimens. Geometrically complex parts (3D) are printed in conventional ME systems without support and improved characteristics through the multi-feature path planning strategy. Each feature is printed according to geometrically determined requirements representing a successful proof-of-concept. Results show that further testing is required for the effects of mechanical resistance at connection areas. Adaption of the path planning strategy is needed to reduce occurring defects.
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Choi, Byeong-Yeol, Seong-Je Park, Yong Son, Seung-Jun Han, Hyung-Giun Kim, Il-Hyuk Ahn, and Woo-Chun Choi. "Influence of Warm Isostatic Press Process on Mechanical Properties of a Part Fabricated by Metal Material Extrusion Process." Applied Sciences 12, no. 23 (November 29, 2022): 12240. http://dx.doi.org/10.3390/app122312240.
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Material extrusion (ME) using a filament including metal powders has recently attracted considerable attention because it allows the production of metal parts at low cost. However, like other additive manufacturing processes, metal ME suffers from the problem of internal pores. In this study, warm isostatic pressure (WIP)—a post-process used to downsize or remove the pores in polymer ME—was employed in metal ME to improve the mechanical properties of the finished part. It was confirmed experimentally that the tensile strength and the strain at the ultimate tensile strength were increased by WIP. However, from hardness tests, two different results were obtained. On a microscopic scale, there was no change in hardness because the temperature of the WIP process was not high enough to change the microstructure, while on a macroscopic scale, the hardness changed owing to the collapse of the pores within the material under the indenter load. In specimens with relatively large pores, the hardness sensitivity increases with a larger indenter. Finally, factors affecting the WIP process parameters in metal ME were discussed.
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Costa, José, Elsa Sequeiros, Maria Teresa Vieira, and Manuel Vieira. "Additive Manufacturing." U.Porto Journal of Engineering 7, no. 3 (April 30, 2021): 53–69. http://dx.doi.org/10.24840/2183-6493_007.003_0005.
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Additive manufacturing (AM) is one of the most trending technologies nowadays, and it has the potential to become one of the most disruptive technologies for manufacturing. Academia and industry pay attention to AM because it enables a wide range of new possibilities for design freedom, complex parts production, components, mass personalization, and process improvement. The material extrusion (ME) AM technology for metallic materials is becoming relevant and equivalent to other AM techniques, like laser powder bed fusion. Although ME cannot overpass some limitations, compared with other AM technologies, it enables smaller overall costs and initial investment, more straightforward equipment parametrization, and production flexibility.This study aims to evaluate components produced by ME, or Fused Filament Fabrication (FFF), with different materials: Inconel 625, H13 SAE, and 17-4PH. The microstructure and mechanical characteristics of manufactured parts were evaluated, confirming the process effectiveness and revealing that this is an alternative for metal-based AM.
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Fenollosa, F., R. Uceda, A. Tejo, L. Calvo, L. Poudelet, and I. Buj. "Research on desktop 3D Printing Multi-Material New Concepts." IOP Conference Series: Materials Science and Engineering 1193, no. 1 (October 1, 2021): 012043. http://dx.doi.org/10.1088/1757-899x/1193/1/012043.
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Abstract 3D printing or Additive Manufacturing (AM) was originally born as a mono-material technology. And, nowadays, most of the applications are still using only one material. AM has a lot of potential but has not yet been fully explored, and access to the creation of multi-material products is an example of it. One of the most interesting areas is the introduction in the same part of materials with different rigidities, stiffer and softer areas, with differentiated values of mechanical strength and viscoelasticity. In the present work, a general vision of Additive Manufacturing under the vision of mono- and multi-material processes is given, and some existing 3D printing multi-material experiences related to Material Jetting (MJ) and Material Extrusion (ME) are briefly described. But it is in this latter field, linked to Desktop 3D printing (more accessible than typical proprietary industrial equipment), where on-going research could easily be spread: five research ME concepts are then presented, from a revolver print-head to silicone UV 3D printing, with their initial embodiment in the form of prototypes or/and testing, as a way to verify the difficulties that would be encountered in the transition from research to reality.
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Narei, Hamid, Maryam Fatehifar, Ashley Howard Malt, John Bissell, Mohammad Souri, Mohammad Nasr Esfahani, and Masoud Jabbari. "Numerical Simulation of a Core–Shell Polymer Strand in Material Extrusion Additive Manufacturing." Polymers 13, no. 3 (February 2, 2021): 476. http://dx.doi.org/10.3390/polym13030476.
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Material extrusion additive manufacturing (ME-AM) techniques have been recently introduced for core–shell polymer manufacturing. Using ME-AM for core–shell manufacturing offers improved mechanical properties and dimensional accuracy over conventional 3D-printed polymer. Operating parameters play an important role in forming the overall quality of the 3D-printed manufactured products. Here we use numerical simulations within the framework of computation fluid dynamics (CFD) to identify the best combination of operating parameters for the 3D printing of a core–shell polymer strand. The objectives of these CFD simulations are to find strands with an ultimate volume fraction of core polymer. At the same time, complete encapsulations are obtained for the core polymer inside the shell one. In this model, the deposition flow is controlled by three dimensionless parameters: (i) the diameter ratio of core material to the nozzle, d/D; (ii) the normalised gap between the extruder and the build plate, t/D; (iii) the velocity ratio of the moving build plate to the average velocity inside the nozzle, V/U. Numerical results of the deposited strands’ cross-sections demonstrate the effects of controlling parameters on the encapsulation of the core material inside the shell and the shape and size of the strand. Overall we find that the best operating parameters are a diameter ratio of d/D=0.7, a normalised gap of t/D=1, and a velocity ratio of V/U=1.
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Lee, Kok Peng Marcian, Milan Brandt, Robert Shanks, and Fugen Daver. "Rheology and 3D Printability of Percolated Graphene–Polyamide-6 Composites." Polymers 12, no. 9 (September 3, 2020): 2014. http://dx.doi.org/10.3390/polym12092014.
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Graphene–polyamide-6 (PA6) composites with up to 17.0%·w/w graphene content were prepared via melt mixing. Oscillatory rheometry revealed that the dynamic viscoelastic properties of PA6 decreased with the addition of 0.1%·w/w graphene but increased when the graphene content was increased to 6.0%·w/w and higher. Further analysis indicated that the rheological percolation threshold was between 6.0 and 10.0%·w/w graphene. The Carreau–Yasuda model was used to describe the complex viscosity of the materials. Capillary rheometry was applied to assess the steady shear rheology of neat PA6 and the 17.0%·w/w graphene–PA6 composite. High material viscosity at low shear rates coupled with intense shear-thinning in the composite highlighted the importance of selecting the appropriate rheological characterisation methods, shear rates and rheological models when assessing the 3D printability of percolated graphene–polymer composites for material extrusion (ME). A method to predict the printability of an ME filament feedstock, based on fundamental equations describing material flow through the printer nozzle, in the form of a printing envelope, was developed and verified experimentally. It was found that designing filaments with steady shear viscosities of approximately 15% of the maximum printable viscosity for the desired printing conditions will be advantageous for easy ME processing.
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Jiang, Shijie, Tiankuo Dong, Yang Zhan, Weibing Dai, and Ming Zhan. "Experimental Study on Improving the Mechanical Properties of Material Extrusion Rapid Prototyping Polylactic Acid Parts by Applied Vibration." Applied Sciences 11, no. 4 (February 18, 2021): 1820. http://dx.doi.org/10.3390/app11041820.
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Due to the stratified nature of the manufacturing process, material extrusion (ME) parts have lower mechanical properties than those fabricated by traditional technology. This is one of the most significant defects hindering the development and application of this rapid prototyping technique. In this paper, vibration was applied to the ME process by using piezoelectric ceramics for the first time to improve the mechanical properties of the built parts. The vibrating ME equipment was established, and the specimens processed in different build directions were individually fabricated without applied vibration and with different applied vibrations. To quantify the effect of applied vibration on their mechanical properties and to summarize the influencing rule, a series of experimental tests were then performed on these specimens. A comparison between the testing results shows that the tensile strength and plasticity of the specimens, especially those processed in the Z direction, can be obviously improved by applied vibration. The orthogonal anisotropy is decreased obviously. The improvement becomes greater with increasing vibration frequency or amplitude. From the microscopic point of view, it can be seen that applied vibration can reduce the part’s defects of porosity and inclusion as well as separation between layers and, thereby, improve the bonding strength.
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Rico-Baeza, Genaro, Enrique Cuan-Urquizo, Gerardo I. Pérez-Soto, Luis A. Alcaraz-Caracheo, and Karla A. Camarillo-Gómez. "Additively Manufactured Lattice Materials with a Double Level of Gradation: A Comparison of Their Compressive Properties when Fabricated with Material Extrusion and Vat Photopolymerization Processes." Materials 16, no. 2 (January 9, 2023): 649. http://dx.doi.org/10.3390/ma16020649.
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Natural porous materials adjust their resulting mechanical properties by the optimal use of matter and space. When these are produced synthetically, they are known as mechanical metamaterials. This paper adds degrees of tailoring of mechanical properties by producing double levels of gradation in lattice structures via cross-section variation in struts in uniformly periodic lattice structures (UPLS) and layered lattice structures (LLS). These were then additively manufactured via material extrusion (ME) and vat photopolymerization (VP). Their effective mechanical properties under compressive loads were characterized, and their stiffness contrasted with finite element models (FEM). According to the simulation and experimental results, a better correlation was obtained in the structures manufactured via VP than by ME, denoting that printing defects affect the correlation results. The brittle natural behavior of the resin caused a lack of a plateau region in the stress–strain curves for the UPLS structures, as opposed to those fabricated with ME. The LLS increased energy absorption up to % and increased the plateau stress up to % compared to the UPLS. The results presented in this paper demonstrate that the mechanical properties of lattice structures with the same base topology could be modified by incorporating variations in the strut diameter and then arranging these differently.
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Vyavahare, Swapnil, Soham Teraiya, and Shailendra Kumar. "Auxetic structures fabricated by material extrusion: an experimental investigation of gradient parameters." Rapid Prototyping Journal 27, no. 5 (June 8, 2021): 1041–58. http://dx.doi.org/10.1108/rpj-05-2020-0107.
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Purpose This paper aims to focus on studying the influence of gradient parameters, namely, thickness coefficient, length coefficient and height ratio of auxetic structure on responses such as strength, stiffness and specific energy absorption (SEA) under compressive loading. Optimization of significant parameters is also performed to maximize responses. Further, efforts have also been made to develop regression models for strength, stiffness and SEA of auxetic structure. Design/methodology/approach Central composite design of response surface methodology is used for planning experiments. Auxetic structures of acrylonitrile butadiene styrene (ABS) and poly-lactic acid (PLA) materials are fabricated by the material extrusion (ME) technique of additive manufacturing. Fabricated structures are tested under in-plane uniaxial compressive loading. Grey relational analysis is used for the optimization of gradient parameters of the unit cell of auxetic structure to maximize responses and minimize weight and time of fabrication. Findings From the analysis of variance of experimental data, it is found that the compressive strength of auxetic structures increases with a decrease in length coefficient and height ratio. In the case of ABS structures, stiffness increases with a decrease in thickness coefficient and length coefficient, while in the case of PLA structures, stiffness increases with a decrease in length coefficient and height ratio. SEA is influenced by length coefficient and thickness coefficient in ABS and PLA structures, respectively. Based on the analysis, statistical non-linear quadratic models are developed to predict strength, stiffness and SEA. Optimal configuration of auxetic structure is determined to maximize strength, stiffness, SEA and minimize weight and time of fabrication. Research limitations/implications The present study is limited to re-entrant type of auxetic structures made of ABS and PLA materials only under compressive loading. Also, results from the current study are valid within a selected range of gradient parameters. The findings of the present study are useful in the optimal selection of gradient parameters for the fabrication of auxetic structures of maximum strength, stiffness and SEA with minimum weight and time of fabrication. These outcomes have wide applications in domains such as automotive, aerospace, sports and marine sectors. Originality/value Limited literature is available on studying the influence of gradient parameters of ME manufactured auxetic structure of ABS and PLA materials on responses, namely, strength, stiffness and SEA under compressive loading. Also, no work has been reported on studying the influence of gradient parameters on mechanical properties, weight and time of fabrication of auxetic structures. The present study is an attempt to fulfil the above research gaps.
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Zaharia, Sebastian Marian, Larisa Anamaria Enescu, and Mihai Alin Pop. "Mechanical Performances of Lightweight Sandwich Structures Produced by Material Extrusion-Based Additive Manufacturing." Polymers 12, no. 8 (August 4, 2020): 1740. http://dx.doi.org/10.3390/polym12081740.
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Material Extrusion-Based Additive Manufacturing Process (ME-AMP) via Fused Filament Fabrication (FFF) offers a higher geometric flexibility than conventional technologies to fabricate thermoplastic lightweight sandwich structures. This study used polylactic acid/polyhydroxyalkanoate (PLA/PHA) biodegradable material and a 3D printer to manufacture lightweight sandwich structures with honeycomb, diamond-celled and corrugated core shapes as a single part. In this paper, compression, three-point bending and tensile tests were performed to evaluate the performance of lightweight sandwich structures with different core topologies. In addition, the main failure modes of the sandwich structures subjected to mechanical tests were evaluated. The main failure modes that were observed from mechanical tests of the sandwich structure were the following: face yielding, face wrinkling, core/skin debonding. Elasto-plastic finite element analysis allowed predicting the global behavior of the structure and stressing distribution in the elements of lightweight sandwich structures. The comparison between the results of bending experiments and finite element analyses indicated acceptable similarity in terms of failure behavior and force reactions. Finally, the three honeycomb, diamond-celled and corrugated core typologies were used in the leading edge of the wing and were impact tested and the results created favorable premises for using such structures on aircraft models and helicopter blade structures.
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Rimkus, Arvydas, Mahmoud M. Farh, and Viktor Gribniak. "Continuously Reinforced Polymeric Composite for Additive Manufacturing—Development and Efficiency Analysis." Polymers 14, no. 17 (August 25, 2022): 3471. http://dx.doi.org/10.3390/polym14173471.
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Additive manufacturing (AM) is a rapidly growing technology, referring to a 3D design process by which digital data builds a physical object in layers by depositing the printed material. The AM has evolved in the aviation, automotive, and medical industries. The AM development for fiber-reinforced composites is the point of current interest, with most research focused on using short fibers. However, notwithstanding particular technological complexities, continuous filaments have superior tensile properties compared to short fibers. Therefore, this manuscript develops an adaptive continuous reinforcement approach for AM based on polymeric material extrusion (ME) technology. It combines the raw material production process, including the ability to varying constituents (e.g., filament materials, reinforcement percentage, and recycled plastic replacement ratio), and the reinforcement efficiency analysis regarding the experimentally verified numerical model. The literature review has identified compatible materials for ensuring sustainable and high-performance plastic composites reinforced with continuous fibers. In addition, it identified the applicability of recycled polymers in developing ME processes. Thus, the study includes an experimental program to investigate the mechanical performance of 3D printed samples (polylactic acid, PLA, matrix reinforced with continuous aramid filament) through a tensile test. Recycled polymer replaced 40% of the virgin PLA. The test results do not demonstrate the recycled polymer’s negative effect on the mechanical performance of the printed samples. Moreover, the recycled material reduced the PLA cost by almost twice. However, together with the potential efficiency of the developed adaptive manufacturing technology, the mechanical characteristics of the printed material revealed room for printing technology improvement, including the aligned reinforcement distribution in the printed product and printing parameters’ setup.
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Ginestra, Paola, Stefano Pandini, and Elisabetta Ceretti. "Hybrid multi-layered scaffolds produced via grain extrusion and electrospinning for 3D cell culture tests." Rapid Prototyping Journal 26, no. 3 (November 27, 2019): 593–602. http://dx.doi.org/10.1108/rpj-03-2019-0079.
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Purpose The purpose of this paper is to focus on the production of scaffolds with specific morphology and mechanical behavior to satisfy specific requirements regarding their stiffness, biological interactions and surface structure that can promote cell-cell and cell-matrix interactions though proper porosity, pore size and interconnectivity. Design/methodology/approach This case study was focused on the production of multi-layered hybrid scaffolds made of polycaprolactone and consisting in supporting grids obtained by Material Extrusion (ME) alternated with electrospun layers. An open source 3D printer was utilized, with a grain extrusion head that allows the production and distribution of strands on the plate according to the designed geometry. Square grid samples were observed under optical microscope showing a good interconnectivity and spatial distribution of the pores, while scanning electron microscope analysis was used to study the electrospun mats morphology. Findings A good adhesion between the ME and electrospinning layers was achieved by compression under specific thermomechanical conditions obtaining a hybrid three-dimensional scaffold. The mechanical performances of the scaffolds have been analyzed by compression tests, and the biological characterization was carried out by seeding two different cells phenotypes on each side of the substrates. Originality/value The structure of the multi-layered scaffolds demonstrated to play an important role in promoting cell attachment and proliferation in a 3D culture formation. It is expected that this design will improve the performances of osteochondral scaffolds with a strong influence on the required formation of an interface tissue and structure that need to be rebuilt.
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Ransikarbum, Kasin, Rapeepan Pitakaso, and Namhun Kim. "A Decision-Support Model for Additive Manufacturing Scheduling Using an Integrative Analytic Hierarchy Process and Multi-Objective Optimization." Applied Sciences 10, no. 15 (July 27, 2020): 5159. http://dx.doi.org/10.3390/app10155159.
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Additive manufacturing (AM) became widespread through several organizations due to its benefits in providing design freedom, inventory improvement, cost reduction, and supply chain design. Process planning in AM involving various AM technologies is also complicated and scarce. Thus, this study proposed a decision-support tool that integrates production and distribution planning in AM involving material extrusion (ME), stereolithography (SLA), and selective laser sintering (SLS). A multi-objective optimization approach was used to schedule component batches to a network of AM printers. Next, the analytic hierarchy process (AHP) technique was used to analyze trade-offs among conflicting criteria. The developed model was then demonstrated in a decision-support system environment to enhance practitioners’ applications. Then, the developed model was verified through a case study using automotive and healthcare parts. Finally, an experimental design was conducted to evaluate the complexity of the model and computation time by varying the number of parts, printer types, and distribution locations.
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Schwartz, Johanna J., Joshua Hamel, Thomas Ekstrom, Leticia Ndagang, and Andrew J. Boydston. "Not all PLA filaments are created equal: an experimental investigation." Rapid Prototyping Journal 26, no. 7 (June 27, 2020): 1263–76. http://dx.doi.org/10.1108/rpj-06-2019-0179.
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Purpose Additive manufacturing (AM) methods such as material extrusion (ME) are becoming widely used by engineers, designers and hobbyists alike for a wide variety of applications. Successfully manufacturing objects using ME three-dimensional printers can often require numerous iterations to attain predictable performance because the exact mechanical behavior of parts fabricated via additive processes are difficult to predict. One of that factors that contributes to this difficulty is the wide variety of ME feed stock materials currently available in the marketplace. These build materials are often sold based on their base polymer material such as acrylonitrile butadiene styrene or polylactic acid (PLA), but are produced by numerous different commercial suppliers in a wide variety of colors using typically undisclosed additive feed stocks and base polymer formulations. This paper aims to present the results from an experimental study concerned with quantifying how these sources of polymer variability can affect the mechanical behavior of three-dimensional printed objects. Specifically, the set of experiments conducted in this study focused on following: several different colors of PLA filament from a single commercial supplier to explore the effect of color additives and three filaments of the same color but produced by three different suppliers to account for potential variations in polymer formulation. Design/methodology/approach A set of five common mechanical and material characterization tests were performed on 11 commercially available PLA filaments in an effort to gain insight into the variations in mechanical response that stem from variances in filament manufacturer, feed stock polymer, additives and processing. Three black PLA filaments were purchased from three different commercial suppliers to consider the variations introduced by use of different feed stock polymers and filament processing by different manufacturers. An additional eight PLA filaments in varying colors were purchased from one of the three suppliers to focus on how color additives lead to property variations. Some tests were performed on unprocessed filament samples, while others were performed on objects three-dimensional printed from the various filaments. This study looked specifically at four mechanical properties (Young’s modulus, storage modulus, yield strength and toughness) as a function of numerous material properties (e.g. additive loading, molecular weight, molecular weight dispersity, enthalpy of melting and crystallinity). Findings For the 11 filaments tested the following mean values and standard deviations were observed for the material properties considered: pa = 1.3 ± 0.9% (percent additives), Mw = 98.6 ± 16.4 kDa (molecular weight), Ð = 1.33 ± 0.1 (molecular weight dispersity), Hm = 37.4 ± 7.2 J/g (enthalpy of melting) and = 19.6 ± 2.1% (crystallinity). The corresponding mean values and standard deviations for the resulting mechanical behaviors were: E = 2,790 ± 145 MPa (Young’s modulus), E’ = 1,050 ± 125 MPa (storage modulus), Sy = 49.6 ± 4.93 MPa (yield strength) and Ut = 1.87 ± 0.354 MJ/m^3 (toughness). These variations were observed in filaments that were all manufactured from the same base polymer (e.g. PLA) and are only different in terms of the additives used by the manufacturers to produce different colors or different three-dimensional printing performance. Unfortunately, while the observed variations were significant, no definitive strong correlations were found between these observed variations in the mechanical behavior of the filaments studied and the considered material properties. Research limitations/implications These variations in mechanical behavior and material properties could not be ascribed to any specific factor, but rather show that the mechanical of three-dimensional printed parts are potentially affected by variations in base polymer properties, additive usage and filament processing choices in complex ways that can be difficult to predict. Practical implications These results emphasize the need to take processing and thereby even filament color, into account when using ME printers, they emphasize the need for designers to use AM with caution when the mechanical behavior of a printed part is critical and they highlight the need for continued research in this important area. While all filaments used were marked as PLA, the feedstock materials, additives and processing conditions created significant differences in the mechanical behavior of the printed objects evaluated, but these differences could not be accurately and reliably predicted as function of the observed material properties that were the focus of this study. Originality/value The testing methods used in the study can be used by engineers and creators alike to better analyze the material properties of their filament printed objects, to increase success in print and mechanical design. Furthermore, the results clearly show that as AM continues to evolve and grow as a manufacturing method, standardization of feedstock processing conditions and additives would enable more reliable and repeatable printed objects and would better assist designers in effectively implementing AM methods.
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Ecker, J. V., K. Dobrezberger, J. Gonzalez-Gutierrez, M. Spoerk, Ch Gierl-Mayer, and H. Danninger. "Additive Manufacturing of Steel and Copper Using Fused Layer Modelling: Material and Process Development." Powder Metallurgy Progress 19, no. 2 (December 1, 2019): 63–81. http://dx.doi.org/10.1515/pmp-2019-0007.
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AbstractFused Layer Modelling (FLM) is one out of several material extrusion (ME) additive manufacturing (AM) methods. FLM usually deals with processing of polymeric materials but can also be used to process metal-filled polymeric systems to produce metallic parts. Using FLM for this purpose helps to save costs since the FLM hardware is cheap compared to e.g. direct metal laser processing hardware, and FLM offers an alternative route to the production of metallic components.To produce metallic parts by FLM, the methodology is different from direct metal processing technologies, and several processing steps are required: First, filaments consisting of a special polymer-metal composition are produced. The filament is then transformed into shaped parts by using FLM process technology. Subsequently the polymeric binder is removed (”debinding”) and finally the metallic powder body is sintered. Depending on the metal powder used, the binder composition, the FLM production parameters and also the debinding and sintering processes must be carefully adapted and optimized.The focal points of this study are as following:1. To confirm that metallic parts can be produced by using FLM plus debinding and sintering as an alternative route to direct metal additive manufacturing.2. Determination of process parameters, depending on the used metal powders (steel and copper) and optimization of each process step.3. Comparison of the production paths for the different metal powders and their debinding and sintering behavior as well as the final properties of the produced parts.The results showed that both materials were printable after adjusting the FLM parameters, metallic parts being produced for both metal powder systems. The production method and the sintering process worked out well for both powders. However there are specific challenges in the sintering process that have to be overcome to produce high quality metal parts. This study serves as a fundamental basis for understanding when it comes to the processing of steel and copper powder into metallic parts using FLM processing technology.
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Mankelow, Tosti J., Rebecca E. Griffiths, Joanna F. Flatt, and David J. Anstee. "Human Reticulocytes Extrude Inside-Out, Phosphatidylserine-Exposed, Autophagic Vesicles During The Final Step In The Formation Of Erythrocytes." Blood 122, no. 21 (November 15, 2013): 941. http://dx.doi.org/10.1182/blood.v122.21.941.941.
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Abstract During maturation to an erythrocyte, a reticulocyte must degrade or eliminate its residual cytosolic organelles and reduce its surface area. Using confocal microscopy, we show that in late reticulocytes produced from an in vitro culture system, this is achieved through a novel form of exocytosis whereby large (∼1.4um) intact, inside-out phosphatidylserine-exposed vesicles are expelled from the maturing reticulocyte. The vesicles contain organelle marker proteins and numerous erythroid membrane proteins, notably CD71, CD147 and stomatin. The presence of ubiquitin within these vesicles suggests a recognised mechanism for the targeting of proteins for extracellular export or degradation. The exocytosed vesicles are identical to intracellular GPA-decorated autophagic vesicles previously identified in cultured reticulocytes (Griffiths et al 2012). GPA-decorated vesicles are also seen in some cells in peripheral blood. Proteins involved in vesicle trafficking, SNARE (VAMP7), ESCRT (CHMP4B) and myosin, locate to defined positions at the point of vesicle extrusion. We hypothesize that the exposed “eat me” phosphatidylserine signal ensures that released autophagic vesicles are rapidly removed from circulation by professional phagocytic cells within the spleen thus ensuring maturation to erythrocytes without the release of potentially toxic material into circulation. Our results describe a previously unrecognised mode of exocytosis which may have significance beyond erythropoiesis particularly with respect to apoptosis and autophagy and reveal the final step in the formation of human erythrocytes. Reference Griffiths RE, Kupzig S, Cogan N, Mankelow TJ, Betin VM, Trakarnsanga K, Massey EJ, Lane JD, Parsons SF, Anstee DJ.Maturing reticulocytes internalize plasma membrane in glycophorin A-containing vesicles that fuse with autophagosomes before exocytosis. Blood. 2012 Jun 28;119(26):6296-306. Disclosures: No relevant conflicts of interest to declare.
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Hernández-Alamilla, Montserrat, and Alex Valadez-Gonzalez. "The effect of two commercial melt strength enhancer additives on the thermal, rheological and morphological properties of polylactide." Journal of Polymer Engineering 36, no. 1 (January 1, 2016): 31–41. http://dx.doi.org/10.1515/polyeng-2014-0322.
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Abstract The effect of two commercial melt strength enhancer additives, Paraloid BPMS-250 (BPMS) and Biostrength 700 (BIOS), on the thermal, rheological and morphological properties of polylactide (PLA) was studied. Thermal analyses showed that both the BPMS and BIOS additives decreased the ability of PLA to crystallize. The rheological tests indicated that zero-shear viscosity and storage modulus of the PLA/BPMS and PLA/BIOS blends were significantly increased with the additive content. These could be attributed to the entanglements between the PLA chains with those of the high molecular weight additive, creating a physical network which reduces the segmental mobility of PLA and improves the melt elasticity of the blend. The entanglement molecular weights (Me) of PLA/BPMS and PLA/BIOS blends were lower than those of unprocessed and processed PLA (Me≈4×104 g/mol), which suggests greater chain entanglements and a higher entanglement density (ve). The elongational viscosity (ηE) and melt strength values were estimated using a screw-extrusion capillary rheometer, where the PLA/BIOS blends presented the highest values. Finally, scanning electron microscopy on the samples was carried out to assess the blend morphology.
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He, Shushu, Jinhui Gao, Peter Wamalwa, Yunji Wang, Shujuan Zou, and Song Chen. "Camouflage treatment of skeletal Class III malocclusion with multiloop edgewise arch wire and modified Class III elastics by maxillary mini-implant anchorage." Angle Orthodontist 83, no. 4 (January 11, 2013): 630–40. http://dx.doi.org/10.2319/091312-730.1.
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ABSTRACT Objective: To evaluate the effect of the multiloop edgewise arch wire (MEAW) technique with maxillary mini-implants in the camouflage treatment of skeletal Class III malocclusion. Materials and Methods: Twenty patients were treated with the MEAW technique and modified Class III elastics from the maxillary mini-implants. Twenty-four patients were treated with MEAW and long Class III elastics from the upper second molars as control. Lateral cephalometric radiographs were obtained and analyzed before and after treatment, and 1 year after retention. Results: Satisfactory occlusion was established in both groups. Through principal component analysis, it could be concluded the anterior-posterior dental position, skeletal sagittal and vertical position, and upper molar vertical position changed within groups and between groups; vertical lower teeth position and Wits distance changed in the experimental group and between groups. In the experimental group, the lower incisors tipped lingually 2.7 mm and extruded 2.4 mm. The lingual inclination of the lower incisors increased 3.5°. The mandibular first molars tipped distally 9.1° and intruded 0.4 mm. Their cusps moved 3.4 mm distally. In the control group, the upper incisors proclined 3°, and the upper first molar extruded 2 mm. SN-MP increased 1.6° and S-Go/N-ME decreased 1. Conclusions: The MEAW technique combined with modified Class III elastics by maxillary mini-implants can effectively tip the mandibular molars distally without any extrusion and tip the lower incisors lingually with extrusion to camouflage skeletal Class III malocclusions. Clockwise rotation of the mandible and further proclination of upper incisors can be avoided. The MEAW technique and modified Class III elastics provided an appropriate treatment strategy especially for patients with high angle and open bite tendency.
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Loh, Giselle Hsiang, Adeayo Sotayo, and Eujin Pei. "Development and testing of material extrusion additive manufactured polymer–textile composites." Fashion and Textiles 8, no. 1 (January 5, 2021). http://dx.doi.org/10.1186/s40691-020-00232-7.
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AbstractThe adoption of Additive Manufacturing (AM) has gradually transformed the fashion industry through innovation and technology over the last decade. Novel AM systems and techniques are continuously being developed, leading to the application of AM polymers with textiles and fabrics in the fashion industry. This work investigates the development and testing of polymer–textile composites using polylactic acid (PLA) filaments on synthetic mesh fabrics using direct material extrusion (ME). An aspect of this paper highlights the appropriate combination of printing material, textile substrate, and printer settings to achieve excellent polymer–textile adhesion. Details of the printing process to create polymer–textile composites are described, as are the interfacial strength results of the T-peel tests, and the observed failure modes post-testing. The peel strengths for different ME bonded polymer–textile composites are examined and used to identify the compatibility of materials. This work visualised the potential of direct ME of polymers onto textile fabrics as a material-joining approach for new textile functionalisation, multi-material composite explorations and innovative aesthetic print techniques. This work also adds to the limited knowledge of AM polymer–textile composites, which can provide helpful information for designers and researchers to develop new applications and facilitate future research development in smart embedded and programmable textiles.
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Obadimu, Solomon O., and Kyriakos I. Kourousis. "Microscopic and mesoscopic/macroscopic structural characteristics of material extrusion Steel 316L: influence of the fabrication process." International Journal of Structural Integrity, September 23, 2022. http://dx.doi.org/10.1108/ijsi-07-2022-0100.
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PurposeThe material extrusion (ME) process induces variations in the final part’s microscopic and macroscopic structural characteristics. This viewpoint article aims to uncover the relation between ME fabrication parameters and the microstructural and mesostructural characteristics of the ME BASF Ultrafuse Steel 316L metal parts. These characteristics can affect the structural integrity of the produced parts and components used in various engineering applications.Design/methodology/approachRecent studies on the ME BASF Ultrafuse Steel 316L are reviewed, with a focus on those which report microstructural and mesostructural characteristics that may affect structural integrity.FindingsA relationship between ME fabrication parameters and subsequent microstructural and mesostructural characteristics is discussed. Common microstructural and mesostructural/macrostructural defects are also highlighted and discussed.Originality/valueThis viewpoint article attempts to bridge the existing gap in the literature, highlighting the influence of ME fabrication parameters on Steel 316L parts fabricated via this additive manufacturing method. Moreover, this article identifies and discusses important considerations for the purposes of selecting and optimising the structural integrity of ME-fabricated Steel 316L parts.
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Chai, Yuan, Xiao-Bo Chen, Donghai Zhang, Joseph Lynch, Nick Birbilis, Qing-Hua Qin, Paul N. Smith, and Rachel W. Li. "Laser polished fused deposition poly-lactic acid objects for personalized orthopaedic application." SN Applied Sciences 2, no. 11 (October 17, 2020). http://dx.doi.org/10.1007/s42452-020-03637-7.
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AbstractPatient-specific surgical guides are increasingly demanded. Material Extrusion (ME) is a popular 3D printing technique to fabricate personalized surgical guides. However, the ME process usually generates deleterious surface topography which is not suitable for orthopaedic emergencies. We designed and optimized parametric combinations of a laser polishing approach as post process to improve the surface quality of ME-made poly-lactic acid (PLA) objects. In this study, we investigated the contribution of processing variables to the mechanical properties and the biocompatibilities in vitro of the ME-made PLA objects. Conventional surface grinding was conducted as comparison. The results demonstrate that the ME-made PLA samples exhibit good mechanical properties and favourable biocompatibility after being post processed using laser polishing. The post laser polishing, as a powerful tool in manufacture of ME-made PLA objects, will open a new approach with a great promise in its applications in personalized and timely management of medical emergencies.
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Runström Eden, Gunilla, Håkan Tinnerberg, Lars Rosell, Rickie Möller, Ann-Charlotte Almstrand, and Anna Bredberg. "Exploring Methods for Surveillance of Occupational Exposure from Additive Manufacturing in Four Different Industrial Facilities." Annals of Work Exposures and Health, September 6, 2021. http://dx.doi.org/10.1093/annweh/wxab070.
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Abstract 3D printing, a type of additive manufacturing (AM), is a rapidly expanding field. Some adverse health effects have been associated with exposure to printing emissions, which makes occupational exposure studies important. There is a lack of exposure studies, particularly from printing methods other than material extrusion (ME). The presented study aimed to evaluate measurement methods for exposure assessment in AM environments and to measure exposure and emissions from four different printing methods [powder bed fusion (PBF), material extrusion (ME), material jetting (MJ), and vat photopolymerization] in industry. Structured exposure diaries and volatile organic compound (VOC) sensors were used over a 5-day working week. Personal and stationary VOC samples and real-time particle measurements were taken for 1 day per facility. Personal inhalable and respirable dust samples were taken during PBF and MJ AM. The use of structured exposure diaries in combination with measurement data revealed that comparatively little time is spent on actual printing and the main exposure comes from post-processing tasks. VOC and particle instruments that log for a longer period are a useful tool as they facilitate the identification of work tasks with high emissions, highlight the importance of ventilation and give a more gathered view of variations in exposure. No alarming levels of VOCs or dust were detected during print nor post-processing in these facilities as adequate preventive measures were installed. As there are a few studies reporting negative health effects, it is still important to keep the exposure as low as reasonable.
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Kubalak, Joseph R., Alfred L. Wicks, and Christopher B. Williams. "Investigation of Parameter Spaces for Topology Optimization With Three-Dimensional Orientation Fields for Multi-Axis Additive Manufacturing." Journal of Mechanical Design 143, no. 5 (October 28, 2020). http://dx.doi.org/10.1115/1.4048117.
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Abstract The layer-by-layer deposition process used in material extrusion (ME) additive manufacturing results in inter- and intra-layer bonds that reduce the mechanical performance of printed parts. Multi-axis (MA) ME techniques have shown potential for mitigating this issue by enabling tailored deposition directions based on loading conditions in three dimensions (3D). Planning deposition paths leveraging this capability remains a challenge, as an intelligent method for assigning these directions does not exist. Existing literature has introduced topology optimization (TO) methods that assign material orientations to discrete regions of a part by simultaneously optimizing material distribution and orientation. These methods are insufficient for MA–ME, as the process offers additional freedom in varying material orientation that is not accounted for in the orientation parameterizations used in those methods. Additionally, optimizing orientation design spaces is challenging due to their non-convexity, and this issue is amplified with increased flexibility; the chosen orientation parameterization heavily impacts the algorithm’s performance. Therefore, the authors (i) present a TO method to simultaneously optimize material distribution and orientation with considerations for 3D material orientation variation and (ii) establish a suitable parameterization of the orientation design space. Three parameterizations are explored in this work: Euler angles, explicit quaternions, and natural quaternions. The parameterizations are compared using two benchmark minimum compliance problems, a 2.5D Messerschmitt–Bölkow–Blohm beam and a 3D Wheel, and a multi-loaded structure undergoing (i) pure tension and (ii) three-point bending. For the Wheel, the presented algorithm demonstrated a 38% improvement in compliance over an algorithm that only allowed planar orientation variation. Additionally, natural quaternions maintain the well-shaped design space of explicit quaternions without the need for unit length constraints, which lowers computational costs. Finally, the authors present a path toward integrating optimized geometries and material orientation fields resulting from the presented algorithm with MA–ME processes.
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Kim, Taehun, Dayeong Hong, Sojin Moon, and Namkug Kim. "Evaluation of formaldehyde, particulate matters 2.5 and 10 emitted to a 3D printing workspace based on ventilation." Scientific Reports 12, no. 1 (December 14, 2022). http://dx.doi.org/10.1038/s41598-022-25957-x.
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AbstractRecently, the development of 3D printing (3DP) technology and its application in various fields have improved our quality of life. However, hazardous materials that affect the human body, such as formaldehyde and particulate matter (PM), are emitted into the air during 3DP. This study measured the formaldehyde, PM10, and PM2.5 emitted by 3DP with the ventilation operation using six materials in material extrusion (ME) and vat photopolymerization (VP) and compared them between the 3DP workspace and the control setting with test–retest validation by two researchers. The experiments were divided into four stages based on the 3DP and ventilation operation. A linear mixed model was used to analyze the mean differences and tendencies between the 3DP workspace and the control setting. The change as ventilation was switched from off to on was evaluated by calculating the area. The differences and tendencies were shown in the statistically significant differences from a post-hoc test (α = 0.0125) except for some cases. There was a significant difference in formaldehyde depending on the ventilation operation; however, only a minor difference in PM10, and PM2.5 was confirmed. The amount of formaldehyde exceeding the standard was measured in all materials during 3DP without ventilation. Therefore, it is recommended to operate ventilation systems.
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Park, Seong Je, Seong Jun Park, Yong Son, and Il Hyuk Ahn. "Influence of warm isostatic press (WIP) process parameters on mechanical properties of additively manufactured acrylonitrile butadiene styrene (ABS) parts." International Journal of Advanced Manufacturing Technology, September 14, 2022. http://dx.doi.org/10.1007/s00170-022-10094-6.
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AbstractOwing to the deposition mechanism, parts fabricated from the material extrusion (ME) process have intrinsic air gaps that negatively impact their mechanical properties. Thus, the amount of air gaps should be minimized. In this study, a warm isostatic press (WIP) process was adopted to decrease the amount of air gaps, resulting in improved mechanical properties using acrylonitrile butadiene styrene (ABS). To identify changes in the mechanical properties, tensile tests were performed with specimens heat-treated by the WIP processes with different pressure–temperature profiles. The influence of the temperature and pressure on tensile strength, elongation at break, and toughness was investigated. Water tightness evaluation was conducted to prove the decrease in the air-gap size. Based on the investigation, the WIP process was concluded to be effective for decreasing the intrinsic air gaps and improving the mechanical properties owing to the increase of the bonding force between the lines and layers, which led to the suggestion of a method that optimizes the parameters of the WIP process.
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Burkhardt, Felix, Benedikt C. Spies, Christian Wesemann, Carl G. Schirmeister, Erik H. Licht, Florian Beuer, Thorsten Steinberg, and Stefano Pieralli. "Cytotoxicity of polymers intended for the extrusion-based additive manufacturing of surgical guides." Scientific Reports 12, no. 1 (May 5, 2022). http://dx.doi.org/10.1038/s41598-022-11426-y.
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AbstractExtrusion-based printing enables simplified and economic manufacturing of surgical guides for oral implant placement. Therefore, the cytotoxicity of a biocopolyester (BE) and a polypropylene (PP), intended for the fused filament fabrication of surgical guides was evaluated. For comparison, a medically certified resin based on methacrylic esters (ME) was printed by stereolithography (n = 18 each group). Human gingival keratinocytes (HGK) were exposed to eluates of the tested materials and an impedance measurement and a tetrazolium assay (MTT) were performed. Modulations in gene expression were analyzed by quantitative PCR. One-way ANOVA with post-hoc Tukey tests were applied. None of the materials exceeded the threshold for cytotoxicity (< 70% viability in MTT) according to ISO 10993-5:2009. The impedance-based cell indices for PP and BE, reflecting cell proliferation, showed little deviations from the control, while ME caused a reduction of up to 45% after 72 h. PCR analysis after 72 h revealed only marginal modulations caused by BE while PP induced a down-regulation of genes encoding for inflammation and apoptosis (p < 0.05). In contrast, the 72 h ME eluate caused an up-regulation of these genes (p < 0.01). All evaluated materials can be considered biocompatible in vitro for short-term application. However, long-term contact to ME might induce (pro-)apoptotic/(pro-)inflammatory responses in HGK.
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Winkler, Philipp W., Robert Csapo, Guido Wierer, Caroline Hepperger, Bernhard Heinzle, Andreas B. Imhoff, Christian Hoser, and Christian Fink. "Sonographic evaluation of lateral meniscal extrusion: implementation and validation." Archives of Orthopaedic and Trauma Surgery, November 20, 2020. http://dx.doi.org/10.1007/s00402-020-03683-1.
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Abstract Introduction Meniscal extrusion (ME) is an important indicator of and prognostic factor for various knee pathologies. To date, no standardized protocol for the ultrasound-based examination of lateral ME exists. The purpose of the present study was to test the reliability and validity of lateral ME measurements using a standardized ultrasound-based examination protocol. Materials and Methods A group consisting of 11 healthy volunteers (Group I, male and female, 18–45 years) as well as a group of 10 consecutive patients who had undergone all-inside lateral meniscal radial tear repair were included (Group II, male and female, 23–43 years). Lateral ME, the main outcome parameter, was measured by ultrasound (US; both groups) and magnetic resonance imaging (MRI; Group II only). Both knees of all subjects were examined in an unloaded state and under axial compression of the knee (50% of body weight). Repeated measurements obtained in Group I by 2 observers were used for reliability testing, and the validity of US was assessed through comparison with MRI data (Group II). Results A total of 66 US images of Group I, obtained by each observer, were analyzed for reliability testing. Forty US and MR images of Group II were assessed for validation. Results showed good interrater (ICC = 0.904) and excellent intrarater (ICC = 0.942) reliability of US-based measurements of lateral ME. Agreement with MRI results was poor (ICC = 0.439), with US systematically overestimating results by 1.1 mm on average. Conclusions Ultrasound is a reliable, quick and cost-effective technique for lateral ME measurement, but results are not readily comparable with MRI. Trial registration The study was registered in the European Union Clinical Trials Register (EudraCT-Number: 2017-005037-24).
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Ardani, I. Gusti Aju Wahju, Ike Sesaria Pratiknjo, and Irwadi Djaharu’ddin. "Correlation between Dentoalveolar Heights and Vertical Skeletal Patterns in Class I Malocclusion in Ethnic Javanese." European Journal of Dentistry, October 8, 2020. http://dx.doi.org/10.1055/s-0040-1717156.
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Abstract Objectives Vertical proportions of the face are important determining factors for diagnosis and planning appropriate orthodontic treatment. Orthodontic patients have different vertical and sagittal skeletal discrepancies, as well as associated varying degrees of dentoalveolar compensations. Dentoalveolar is a functional component of the jaw; it plays a role in occlusal dynamics and forms sagittal and vertical maxilla–mandibula relationships. This study aims to analyze the relationship between dentoalveolar heights and several vertical skeletal patterns in patients with Class I malocclusion in ethnic Javanese. Materials and Methods The sample consisted of lateral cephalograms of 75 patients (18 samples were male, and 57 were female). Determined by inclusion and exclusion criteria, the participants were selected from an initial sample of 196 patients with skeletal Class I malocclusion (sella–nasion–A and B [ANB] = 1–4 degrees). Cephalometric analysis was performed using OrthoVision2017 digital software. This analysis measured upper anterior dental height (UADH), upper posterior dental height (UPDH), lower anterior dental height (LADH), lower posterior dental height (LPDH), ANB angle, sella–nasion and mandibular plane (SN-MP), sella–nasion and palatal plane (SN-PP), palatal plane and mandibular plane (PP-MP), Frankfort horizontal plane and mandibular plane (FH-MP), sella to gonion (S-Go), articulare to gonion (Ar-Go), nasion to menton (N-Me), nasion to anterior nasal spine (N-ANS), and anterior nasal spine to menton (ANS-Me). Pearson correlation test was used to assess correlations among all variables (p < 0.05). Results Significant correlations were observed between dentoalveolar heights and SN-MP, S-Go, Ar-Go, N-Me, and ANS-Me (p < 0.05). Conclusions Patients with Class I malocclusion in ethnic Javanese exhibit a significant correlation between dentoalveolar and vertical skeletal patterns. UPDH and/or LPDH have a significantly positive correlation with SN-MP, S-Go, Ar-Go, N-Me, and ANS-Me. The orthodontic correction of the decreased or increased facial height included either the extrusion or intrusion of the anterior or posterior teeth in different ways.
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Kozakiewicz-Latała, Marta, Anna Junak, Adrianna Złocińska, Wojciech Pudło, Krystian Prusik, Patrycja Szymczyk-Ziółkowska, Bożena Karolewicz, and Karol P. Nartowski. "Adjusting the melting point of an Active Pharmaceutical Ingredient (API) via cocrystal formation enables processing of high melting drugs via combined hot melt and materials extrusion (HME and ME)." Additive Manufacturing, October 2022, 103196. http://dx.doi.org/10.1016/j.addma.2022.103196.
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