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Статті в журналах з теми "Fused polymer extrusion":
1
Singamneni, Sarat, Dawn Smith, Marie-Joo LeGuen, and Derryn Truong. "Extrusion 3D Printing of Polybutyrate-Adipate-Terephthalate-Polymer Composites in the Pellet Form." Polymers 10, no. 8 (August 17, 2018): 922. http://dx.doi.org/10.3390/polym10080922.
Анотація:
Fused deposition modelling is a common 3D printing technique used for the freeform fabrication of complex shapes based on polymers. Acrylonitrile butadiene styrene (ABS) is the common material option, though polylactide (PLA) has also proved to be a successful candidate. There is an ever increasing demand to harness new materials as possible candidates for fused deposition. The current research is focused on evaluating polybutyrate-adipate-terephthalate–polymer (PBAT) for fused deposition modelling. Both neat and composite PBAT filled with varying wood flour fillers were experimentally analyzed for 3D printing by extrusion from the pellet forms. The results are positive and the addition of small quantities of the wood flour filler material was found to improve the thixotropic nature of the polymer composite and consequently the inter-strand and inter-layer coalescence.
2
Ramanath, H. S., M. Chandrasekaran, Chee Kai Chua, Kah Fai Leong, and Ketan D. Shah. "Modelling of Extrusion Behaviour of Biopolymer and Composites in Fused Deposition Modelling." Key Engineering Materials 334-335 (March 2007): 1241–44. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.1241.
Анотація:
Processing of polymers plays an important role in application of polymers in biomedical engineering, for instance in manufacture of scaffolds for tissue engineering applications. Rapid prototyping technologies like fused deposition modeling (FDM) has been widely used in processing polymers for biomedical applications. The present work is focused on modeling of flow behavior in the extrusion liquefier in FDM. A finite element (FE) model of extrusion liquefier was constructed on ANSYS after verification of internal geometry using X-ray imaging. Polycaprolactone (PCL) is used as the base bio polymer for analysis. Experiments were carried out to characterize the physical properties like thermal conductivity, specific heat, viscosity and shear thinning property of PCL. These values were used for behavior modeling in the extrusion liquefier. The thermal and flow behavior in the extrusion liquefier is studied by varying input conditions and analyzing the velocity, pressure drop profiles at various zones of extrusion liquefier. Experimental values of parameters and the simulated flow model showed good correlation. The current model can be extended to predict the flow behavior of PCL/ Hydroxyapatite composites in a FDM head which in turn will reflect on the quality of scaffold constructed using the Biocomposite.
3
Badarinath, Rakshith, and Vittaldas Prabhu. "Real-Time Sensing of Output Polymer Flow Temperature and Volumetric Flowrate in Fused Filament Fabrication Process." Materials 15, no. 2 (January 14, 2022): 618. http://dx.doi.org/10.3390/ma15020618.
Анотація:
In this paper we addressed key challenges in engineering an instrumentation system for sensing and signal processing for real-time estimation of two main process variables in the Fused-Filament-Fabrication process: (i) temperature of the polymer melt exiting the nozzle using a thermocouple; and (ii) polymer flowrate using extrusion width measurements in real-time, in-situ, using a microscope camera. We used a design of experiments approach to develop response surface models for two materials that enable accurate estimation of the polymer exit temperature as a function of polymer flowrate and liquefier temperature with a fit of R2=99.96% and 99.39%. The live video stream of the deposition process was used to compute the flowrate based on a road geometry model. Specifically, a robust extrusion width recognizer REXR algorithm was developed to identify edges of the deposited road and for real-time computation of extrusion width, which was found to be robust to filament colors and materials. The extrusion width measurement was found to be within 0.08 mm of caliper measurements with an R2 value of 99.91% and was found to closely track the requested flowrate from the slicer. This opens new avenues for advancing the engineering science for process monitoring and control of FFF.
4
Azad, Mohammad A., Deborah Olawuni, Georgia Kimbell, Abu Zayed Md Badruddoza, Md Shahadat Hossain, and Tasnim Sultana. "Polymers for Extrusion-Based 3D Printing of Pharmaceuticals: A Holistic Materials–Process Perspective." Pharmaceutics 12, no. 2 (February 3, 2020): 124. http://dx.doi.org/10.3390/pharmaceutics12020124.
Анотація:
Three dimensional (3D) printing as an advanced manufacturing technology is progressing to be established in the pharmaceutical industry to overcome the traditional manufacturing regime of 'one size fits for all'. Using 3D printing, it is possible to design and develop complex dosage forms that can be suitable for tuning drug release. Polymers are the key materials that are necessary for 3D printing. Among all 3D printing processes, extrusion-based (both fused deposition modeling (FDM) and pressure-assisted microsyringe (PAM)) 3D printing is well researched for pharmaceutical manufacturing. It is important to understand which polymers are suitable for extrusion-based 3D printing of pharmaceuticals and how their properties, as well as the behavior of polymer–active pharmaceutical ingredient (API) combinations, impact the printing process. Especially, understanding the rheology of the polymer and API–polymer mixtures is necessary for successful 3D printing of dosage forms or printed structures. This review has summarized a holistic materials–process perspective for polymers on extrusion-based 3D printing. The main focus herein will be both FDM and PAM 3D printing processes. It elaborates the discussion on the comparison of 3D printing with the traditional direct compression process, the necessity of rheology, and the characterization techniques required for the printed structure, drug, and excipients. The current technological challenges, regulatory aspects, and the direction toward which the technology is moving, especially for personalized pharmaceuticals and multi-drug printing, are also briefly discussed.
5
Bartolai, Joseph, Timothy W. Simpson, and Renxuan Xie. "Predicting strength of additively manufactured thermoplastic polymer parts produced using material extrusion." Rapid Prototyping Journal 24, no. 2 (March 12, 2018): 321–32. http://dx.doi.org/10.1108/rpj-02-2017-0026.
Анотація:
Purpose The weakest point in additively manufactured polymer parts produced by material extrusion additive manufacturing (MEAM) is the interface between adjacent layers and deposition toolpaths or “roads”. This study aims to predict the mechanical strength of parts by utilizing a novel analytical approach. Strength predictions are made using the temperature history of these interfaces, polymer rheological data, and polymer weld theory. Design/methodology/approach The approach is validated using experimental data for two common 3D-printed polymers: polycarbonate (PC) and acrylonitrile butadiene styrene (ABS). Interface temperature history data are collected in situ using infrared imaging. Rheological data of the polycarbonate and acrylonitrile butadiene styrene used to fabricate the fused filament fabrication parts in this study have been determined experimentally. Findings The strength of the interfaces has been predicted, to within 10% of experimental strength, using polymer weld theory from the literature adapted to the specific properties of the polycarbonate and acrylonitrile butadiene styrene feedstock used in this study. Originality/value This paper introduces a novel approach for predicting the strength of parts produced by MEAM based on the strength of interfaces using polymer weld theory, polymer rheology, temperature history of the interface and the forces applied to the interface. Unlike methods that require experimental strength data as a prediction input, the proposed approach is material and build orientation agnostic once fundamental parameters related to material composition have been determined.
6
Prusinowski, Artur, and Roman Kaczyński. "Simulation of Processes Occurring in the Extrusion Head Used in Additive Manufacturing Technology." Acta Mechanica et Automatica 11, no. 4 (December 1, 2017): 317–21. http://dx.doi.org/10.1515/ama-2017-0049.
Анотація:
AbstractThe purpose of this research is unsatisfactory state of knowledge of the abrasive wear of composites with thermoplastic polymer as matrix material and reinforcing material in the form of short and focused carbon fibers that can be used in additive manufacturing technologies. The paper presents a conceptual design of an extrusion head used in Fused Deposition Technology, which allows for the implementation of appropriately stacked fibers at the level of detail production. Finite element simulation was performed to simulate the thermal effect of the system to demonstrate the effect of head cooling on the system. The assumed extrusion temperature of the material was obtained at a uniform nozzle temperature and stable temperature of the entire system. Flow simulation of thermoplastic polymer was carried out in the designed extrusion nozzle. By supplying 0.5 mm wire of 1.75 mm diameter thermoplastic material to the nozzle, the extrusion rate was 0.192 m/s. The proper design of the extrusion head for the intended applications has been demonstrated and the purpose of further research in this field has been confirmed.
7
Sa'ude, Nasuha, Mustaffa Ibrahim, and Mohd Halim Irwan Ibrahim. "Melt Flow Behavior of Polymer Matrix Extrusion for Fused Deposition Modeling (FDM)." Applied Mechanics and Materials 660 (October 2014): 89–93. http://dx.doi.org/10.4028/www.scientific.net/amm.660.89.
Анотація:
This paper presents the melt flow behavior (MFB) of an acrylonitrile butadiene styrene (ABS), High Density Polyethlene (HDPE), Polyproplene (PP) and a combination of ABS-Iron in the extrusion process. In this study, the effect MFB of variety's polymers and ABS mix with 10% Iron material was investigated based on the viscosity, density, thermal conductivity, melting temperature and specific heat material properties. The MFB of FDM system was investigated using Finite-Element Analysis (FEA) by ANSYS CFX 12. Based on the result obtained, it was found that, the material velocity increase when the nozzle diameter is smaller than the entrance diameter. The higher temperature distribution along the MFB of ABS mix with 10% Iron is 43.15 K compared with original ABS, which is 539.15K.
8
Hanemann, Thomas, Diana Syperek, and Dorit Nötzel. "3D Printing of ABS Barium Ferrite Composites." Materials 13, no. 6 (March 24, 2020): 1481. http://dx.doi.org/10.3390/ma13061481.
Анотація:
In this work, a process for the realization of new polymer matrix composites with nanosized barium ferrite (BaFe12O19) as ferrimagnetic filler, acryl butadiene styrene (ABS) as polymer matrix and an extrusion-based method, namely fused filament fabrication (FFF), as 3D printing method will be described comprehensively. The whole process consists of the individual steps material compounding, rheological testing, filament extrusion, 3D-printing via FFF and finally a widespread specimen characterization regarding to appearance, mechanical properties like tensile and bending behavior as well as the aspired magnetic properties. Increasing ferrite amounts up to 40 vol.% (equal 76 wt.%) cause a reduction of the ultimate stress and an increase of the magnetic polarization as well as of the energy product (BH)max in comparison to the pure polymer matrix. In addition, an extensive discussion of typical printing defects and their consequences on the device properties will be undertaken.
9
Pereira, Gabriela G., Sara Figueiredo, Ana Isabel Fernandes, and João F. Pinto. "Polymer Selection for Hot-Melt Extrusion Coupled to Fused Deposition Modelling in Pharmaceutics." Pharmaceutics 12, no. 9 (August 22, 2020): 795. http://dx.doi.org/10.3390/pharmaceutics12090795.
Анотація:
Three-dimensional (3D) printing offers the greatest potential to revolutionize the future of pharmaceutical manufacturing by overcoming challenges of conventional pharmaceutical operations and focusing design and production of dosage forms on the patient’s needs. Of the many technologies available, fusion deposition modelling (FDM) is considered of the lowest cost and higher reproducibility and accessibility, offering clear advantages in drug delivery. FDM requires in-house production of filaments of drug-containing thermoplastic polymers by hot-melt extrusion (HME), and the prospect of connecting the two technologies has been under investigation. The ability to integrate HME and FDM and predict and tailor the filaments’ properties will extend the range of printable polymers/formulations. Hence, this work revises the properties of the most common pharmaceutical-grade polymers used and their effect on extrudability, printability, and printing outcome, providing suitable processing windows for different raw materials. As a result, formulation selection will be more straightforward (considering the characteristics of drug and desired dosage form or release profile) and the processes setup will be more expedite (avoiding or mitigating typical processing issues), thus guaranteeing the success of both HME and FDM. Relevant techniques used to characterize filaments and 3D-printed dosage forms as an essential component for the evaluation of the quality output are also presented.
10
Villacres, Jorge, David Nobes, and Cagri Ayranci. "Additive manufacturing of shape memory polymers: effects of print orientation and infill percentage on mechanical properties." Rapid Prototyping Journal 24, no. 4 (May 14, 2018): 744–51. http://dx.doi.org/10.1108/rpj-03-2017-0043.
Анотація:
Purpose Material extrusion additive manufacturing, also known as fused deposition modeling, is a manufacturing technique in which objects are built by depositing molten materials layer-by-layer through a nozzle. The use and application of this technique has risen dramatically over the past decade. This paper aims to first, report on the production and characterization of a shape memory polymer material filament that was manufactured to print shape memory polymer objects using material extrusion additive manufacturing. Additionally, it aims to investigate and outline the effects of major printing parameters, such as print orientation and infill percentage, on the elastic and mechanical properties of printed shape memory polymer samples. Design/methodology/approach Infill percentage was tested at three levels, 50, 75 and 100 per cent, while print orientation was tested at four different angles with respect to the longitudinal axis of the specimens at 0°, 30°, 60° and 90°. The properties examined were elastic modulus, ultimate tensile strength and maximum strain. Findings Results showed that print angle and infill percentage do have a significant impact on the manufactured test samples. Originality/value Findings can significantly influence the tailored design and manufacturing of smart structures using shape memory polymer and material extrusion additive manufacturing.
Дисертації з теми "Fused polymer extrusion":
1
Hebda, Michael J. "Creation of controlled polymer extrusion prediction methods in fused filament fabrication. An empirical model is presented for the prediction of geometric characteristics of polymer fused filament fabrication manufactured components." Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/18399.
Анотація:
This thesis presents a model for the procedures of manufacturing Fused Filament Fabrication (FFF) components by calculating required process parameters
using empirical equations. Such an empirical model has been required within the
FFF field of research for a considerable amount of time and will allow for an expansion in understanding of the fundamental mathematics of FFF. Data acquired
through experimentation has allowed for a data set of geometric characteristics
to be built up and used to validate the model presented. The research presented
draws on previous literature in the fields of additive manufacturing, machine engineering, tool-path programming, polymer science and rheology. Combining these
research fields has allowed for an understanding of the FFF process which has
been presented in its simplest form allowing FFF users of all levels to incorporate
the empirical model into their work whilst still allowing for the complexity of the
process.
Initial literature research showed that Polylactic Acid (PLA) is now in common
use within the field of FFF and therefore was selected as the main working material for this project. The FFF technique, which combines extrusion and Computer
Aided Manufacturing (CAM) techniques, has a relatively recent history with little understood about the fundamental mathematics governing the process. This
project aims to rectify the apparent gap in understanding and create a basis upon
which to build research for understanding complex FFF techniques and/or processes involving extruding polymer onto surfaces.
2
Ansari, Mubashir Qamar. "Generation of Thermotropic Liquid Crystalline Polymer (TLCP)-Thermoplastic Composite Filaments and Their Processing in Fused Filament Fabrication (FFF)." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/99885.
Анотація:
One of the major limitations in Fused Filament Fabrication (FFF), a form of additive manufacturing, is the lack of composites with superior mechanical properties. Traditionally, carbon and glass fibers are widely used to improve the physical properties of polymeric matrices. However, the blending methods lead to fiber breakage, preventing generation of long fiber reinforced filaments essential for printing load-bearing components. Our approach to improve tensile properties of the printed parts was to use in-situ composites to avoid fiber breakage during filament generation. In the filaments generated, we used thermotropic liquid crystalline polymers (TLCPs) to reinforce acrylonitrile butadiene styrene (ABS) and a high performance thermoplastic, polyphenylene sulfide (PPS). The TLCPs are composed of rod-like monomers which are highly aligned under extensional kinematics imparting excellent one-dimensional tensile properties. The tensile strength and modulus of the 40 wt.% TLCP/ABS filaments was improved by 7 and 20 times, respectively. On the other hand, the 67 wt.% TLCP/PPS filament tensile strength and modulus were improved by 2 and 12 times, respectively.
The filaments were generated using dual extrusion technology to produce nearly continuously reinforced filaments and to avoid matrix degradation. Rheological tests were taken advantage of to determine the processing conditions. Dual extrusion technology allowed plasticating the matrix and the reinforcing polymer separately in different extruders. Then continuous streams of TLCP were injected below the TLCP melting temperature into the matrix polymer to avoid matrix degradation. The blend was then passed through a series of static mixers, subdividing the layers into finer streams, eventually leading to nearly continuous fibrils which were an order of magnitude lower in diameter than those of the carbon and glass fibers.
The composite filaments were printed below the melting temperature of the TLCPs, and the conditions were determined to avoid the relaxation of the order in the TLCPs. On printing, a matrix-like printing performance was obtained, such that the printer was able to take sharp turns in comparison with the traditionally used fibers. Moreover, the filaments led to a significant improvement in the tensile properties on using in FFF and other conventional technologies such as injection and compression molding.Doctor of Philosophy
3
Authelin, Olivier. "Méthodologie de préparation à la fabrication de composants de grandes dimensions à partir de matériaux polymères thermoplastiques fondus." Thesis, Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0006.
Анотація:
La fabrication additive de composants de grandes dimensions à partir de matériaux polymères thermoplastiques fondus connaît depuis les années 2010 un essor important, l’arrivée de matériaux innovants ayant permis de réaliser un bond en avant en termes de propriétés mécaniques intrinsèques. La réalisation de démonstrateurs de grandes dimensions, développés au sein de la littérature scientifique, a mis en lumière la pertinence de ce procédé pour la réalisation d’applications structurelles(équipements sportifs, ponts pédestres) et non structurelles (moules et outillages de grandes dimensions). En effet, lesavantages de ce procédé sont nombreux, comme par exemple la fabrication de composants personnalisés ou la réduction des coûts et des délais d’obtention. Cependant, ressortent de l’analyse de l’état de l’art des verrous scientifiques relatifs à la fabrication de ces démonstrateurs de grandes dimensions :- la façon de procéder, de type « essais - erreurs – corrections », est coûteuse en temps, en ressources et en argent. Il n’existe pas de consensus concernant une méthode générique qui permette de réaliser des composants de grandes dimensions ;- des problématiques concernant la génération des trajectoires de fabrication en vue de respecter un cahier des charges et le choix d’un moyen de fabrication adapté doivent être résolues.Dans le cadre de ce manuscrit est développée une méthodologie de préparation à la fabrication de composants de grandes dimensions réalisés à partir de matériaux polymères thermoplastiques fondus. Elle propose une préparation à la fabrication générique, basée sur un ensemble de règles métier intégrant la prise en compte des problématiques précédemment mentionnées. Les étapes de la méthodologie sont traitées de manière chronologique au sein des chapitres dans lesquels les problématiques spécifiques et les solutions mises en place pour les résoudre sont explicitées. Un axe de recherche consacré au renforcement des composants à partir de matériaux renforcés de fibres continues afin de pallier la problématique d’anisotropie des propriétés mécaniques inhérente aux procédés additifs basés sur l’extrusion de polymères fondus, est notamment développé. Pour finir, la réalisation de démonstrateurs de grandes dimensions permet de mettre en lumière la pertinence des éléments présentés au sein de la méthodologie mais aussi les perspectives pouvant lui être apportéesLarge-sized additively manufactured components made of thermoplastic polymer materials has experienced significant growth since the 2010s, the arrival of innovative materials having made possible to achieve a leap forward in terms of intrinsic mechanical properties. Large-scale demonstrators manufacturing, developed within the scientific literature, has highlighted therelevance of this process for the realization of structural (sports equipments, pedestrian bridges) and non-structural (large-dimension molds and tools) applications. Indeed, the advantages of this process are numerous, such as for example personalized components manufacturing or costs and lead times reduction. However, large-scale demonstrators manufacturing scientific obstacles resulting from state-of-the-art analysis emerges:- “trial - error - correction” procedure is costly in time, resources and money. There is no consensus on a generic method that allows large components manufacturing preparation;- issues concerning toolpaths generation in order to comply with specifications and the choice of a suitable manufacturing means must be resolved. Within the framework of this manuscript is developed a preparation methodology for large-sized components manufacturing made from fused thermoplastic polymer materials. It offers preparation for generic manufacturing, based on a set of process specific rules integrating the consideration of the previously mentioned issues. The steps of the methodology are processed chronologically in each chapter of the manuscript in which the specific issues and the solutions put in place to resolve them are explained. A research axis dedicated to components reinforcement from continuous fibers reinforced materials in order to overcome mechanical properties anisotropy, inherent in additive processes based on fused thermoplastic polymer materials is notably developed. Finally, large-scale demonstrators manufacturing makes it possible to highlight the methodology relevance but also the perspectives that can be brought to it
4
Ersu, Dilek. "Preparation And Characterization Of Nanocomposites With A Thermoplastic Matrix And Spherical Reinforcement." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607447/index.pdf.
Анотація:
The aim of this study is to investigate the effects of compatibilizers, fumed silica and mixing order of components on morphological, thermal, mechanical and flow properties of LDPE/Fumed silica nanocomposites. As compatibilizer(Co)ethylene/n-butyl acrylate/maleic anhydride (E-nBA-MAH), ethylene/glycidyl methacrylate (E-GMA) and ethylene/methyl acrylate/glycidyl methacrylate (E-MA-GMA) Lotader®
resins
as silica Cab-o-sil®
M5 fumed silica were used. All samples were prepared by means of a lab scale co-rotating twin screw extruder and injection molded into standard samples. In the first step, individual effects of filler and compatibilizers were studied in binary systems with LDPE. Then, keeping the amount of compatibilizer constant at 5%, ternary nanocomposites were prepared by adding 2 or 5% of fumed silica using different component mixing orders. Among investigated mixing orders, mechanical test results showed that the best sequences of component addition are FO1 [(LDPE+Co)+M5] and FO2 [(LDPE+M5)+Co] mixing orders. Considering the compatibilizers, E-nBA-MAH terpolymer showed the highest performance in improving the mechanical properties, E-GMA copolymer also gave satisfactory results. According to the DSC analysis, since addition of fumed silica and compatibilizer does not influence the crystallization behavior of the compositions, it is concluded that, neither fumed silica nor any of the compatibilizers have nucleation activity on LDPE. MFI test results showed that, addition of fumed silica increases the melt viscosity, decreasing MFI values of samples. This change seems to be directly proportional to fumed silica amount.
Частини книг з теми "Fused polymer extrusion":
1
(Ross) Salary, Roozbeh. "Advanced Manufacturing for Bone Tissue Engineering and Regenerative Medicine." In Advanced Additive Manufacturing [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102563.
Анотація:
This book chapter delineates advanced additive manufacturing processes used in clinical practice for high-resolution fabrication of mechanically-robust and dimensionally-accurate bone tissue scaffolds with a focus on pneumatic micro-extrusion, fused deposition modeling, polymer jet printing, and digital light processing. The main components as well as the underlying physics behind each process are explained. Furthermore, this chapter is integrated with a review of literature; the aim is to show how these additive manufacturing processes are potentially utilized in clinical practice for bone tissue engineering. This chapter serves as an introductory platform toward advanced studies and/or research works in the area of bone regenerative medicine. Finally, this chapter will be helpful to engineering and medical students as well as researchers from academia and industry.
Тези доповідей конференцій з теми "Fused polymer extrusion":
1
Singamneni, Sarat, Bin Huang, and Karl Davidson. "Polystyrene in Granular Form for Fused Deposition Modeling." In ASME/ISCIE 2012 International Symposium on Flexible Automation. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/isfa2012-7198.
Анотація:
Fused deposition modeling has become one of the most successful rapid prototyping technologies, and is probably the candidate for the future rapid manufacturing, challenging its traditional counterpart, injection moulding in small to medium scale production. While ABS polymer is the predominant material currently used, the filament form being a precursor, adds up to initial costs, resulting in poor economics. Alternative materials were attempted earlier, but all of them invariably undertook the filament path, necessitating the production of the filament as the first step. The current paper addresses the question if thermoplastic polymers in the granule form could directly be used for fused deposition modeling. Initial experimental results involving the extrusion of polystyrene through a portable polymer extrusion head are promising, and open up further avenues for research.
2
Rodríguez, José F., James P. Thomas, and John E. Renaud. "Characterizing the Microstructure of Fused Deposition Polymer Components." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0636.
Анотація:
Abstract The speed and accuracy with which Fused Deposition (FD) ABS plastic components can be made gives this rapid-prototyping technology unique potential as a new method for manufacturing complex structural components. Quantitative relationships between the FD process variables and the resulting mechanical properties are needed for intelligent manufacture of polymer components with tailored strength properties. This work examined the influence of the process variables on the resulting microstructure (void and interface bond length densities) of two configurations with uniaxial fiber orientation. The results showed the void and interface densities to be strongly dependent on the fiber-to-fiber gap and extrusion flow rate settings; the influence of extrusion and envelope temperatures is much smaller. The skewed fiber configuration exhibited the lowest void density but also the lowest interface density values. However, the difference observed in the values for the interface density were not as big as for the case of the void density. An investigation of the influence of the process variables on the interface bond strengths and the tensile behavior of pre- and post-extruded fibers as a function of loading rate and test temperature is in progress.
3
Ayad, Mustafa, Robert Nawrocki, Richard M. Voyles, Junseok Lee, Hyowon Lee, and Daniel Leon-Salas. "NUCLEOs: Toward Rapid-Prototyping of Robotic Materials That Can Sense, Think and Act." In ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/smasis2018-8245.
Анотація:
Robotic Materials are materials that have sensing, computation and, possibly actuation, distributed throughout the bulk of the material. In such a material, we envision semiconducting polymer based sensing, actuation, and information processing for on-board decision making to be designed, in tandem, with the smart product that will be implemented with the smart material. Prior work in printing polymer semiconductors for sensing and cognition have focused on highly energetic inkjet printing. Alternatively, we are developing liquid polymer extrusion processes to work hand-in-hand with existing solid polymer extrusion processes (such as Fused Deposition Manufacturing - FDM) to simultaneously deposit sensing, computation, actuation and structure. We demonstrate the successful extrusion printing of conductors and capacitors to impedance-match a new, higher-performance organic transistor design that solves the cascading problem of the device previously reported and is more amenable to liquid extrusion printing. Consequently, these printed devices are integrated into a sheet material that is folded into a 3-D, six-legged walking machine with attached electric motor.
4
Ansari, Ajmal I. "Post Extrusion Cooling of Multilayer Polymer Sheet on Chilled Rolls." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72459.
Анотація:
To meet the stringent emission and environmental regulations, polymer sheet with as many as six layers is required for thermoformed fuel tanks used in the automotive industry. The 10 mm to 12 mm thick sheet is made using an extrusion process. Typically each polymer layer has its own hopper, screw, barrel, nozzle and extruder. During manufacturing, polymer layers are fused together within the tool and the multilayer polymer sheet leaves the extruder in a viscoelastic state. The multilayer sheet is initially cooled by passing it over chilled rolls. The final cooling of the sheet is done via natural convection to the ambient air while the sheet is transported to the cutting station at the end of the line. The cooling of the sheet on the chilled and polished rolls has a direct influence on the quality of the sheet as well as the scrap. The conductive heat transfer is primarily responsible for the cooling while the sheet is on the chilled roll. It is desired to have the smooth sheet exterior surfaces with constant thickness of each polymer layer in the cross section. Due to the numerous materials in the cross section, and associated variability of material properties, it becomes a challenging task to meet these requirements. This paper discusses the problem of the smoothness of the exterior surfaces of the extruded sheet. The “dimpled” or “orange peel” surface finish is observed to be linked to the cooling of the sheet on the chilled rolls. Experimental data and simulation results are presented that relate the formation of dimples to the local cooling rate. The variability of thermal contact resistance between the sheet surface and the chill rolls also appear to be another variable that contributes to the dimpled surface.
5
Armstrong, Connor D., Thomas Carlacci, and David Bigio. "Control of Continuous Polymer Compounding Fuse Filament Modeling." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87114.
Анотація:
Controlled processing of carbon microfiber (CMF) reinforced polymers widens control of material properties of fabricated parts. Continuous transfer from compounding to Fused Filament Modeling (FFM) platform brings this advantage to additive manufacturing. CMF reinforced composites are compounded using a co-rotating twin screw extrusion machine (CoTSE). Controlled, direct transfer from the CoTSE to FFM is accomplished using a mechanical system comprised of interconnected feedback control subsystems. Controlled transfer of CMF reinforced composite polymers is studied over a selected range of temperatures, volumetric flow conditions, and microfiber weight fractions using the system. Characteristics of the produced materials are discussed with respect to CMF weight fractions and processing conditions.
6
Krishnanand and Mohammad Taufik. "Design and Development of Pellets/Granules Extrusion System for Additive Manufacturing." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-71083.
Анотація:
Abstract Fused filament fabrication (FFF) is one of the state-of-art and most popular extrusion-based additive manufacturing technology. This technology is popular due to its affordability, simple design, and compact size. In FFF technology, a wire form polymer material called filament is pushed inside a heated chamber using an extruder motor and teethed wheel. In a heated chamber, this filament is converted into semi-solid form and extruded out of the nozzle to fabricate the part. Producing the wire from raw polymer increases the cost as well as limits the used material up to such polymers, which could form a thin and long, continuous, and uniform wire with certain rigidity and other mechanical properties. Hence, the use of filament increases the cost of FFF technology and available wire-based 3D printers are limited by their material availability in the form of wire. These limitations could be eliminated by using a screw-based extrusion mechanism, in which feed materials would be used in pellets or granules form. Since studies on the development of commercial 3D printers based on pellets/granules extrusion were usually neglected. Hence, in this study initial efforts have been made to design and develop a pellets/granules-extruder, which does accept a wide range of materials that are generally available in the market for conventional manufacturing processes. Further, flexible materials and the material which can’t be converted into filament could also be used as feed material in the form of pellets/granules by using the developed system to fabricate a part for different industrial applications.
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McGrady, Garrett, and Kevin Walsh. "Dual Extrusion FDM Printer for Flexible and Rigid Polymers." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8377.
Анотація:
Abstract Commercially available fused deposition modeling (FDM) printers have yet to bridge the gap between printing soft, flexible materials and printing hard, rigid materials. This work presents a custom printer solution, based on open-source hardware and software, which allows a user to print both flexible and rigid polymer materials. The materials printed include NinjaFlex, SemiFlex, acrylonitrile-butadiene-styrene (ABS), Nylon, and Polycarbonate. In order to print rigid materials, a custom, high-temperature heated bed was designed to act as a print stage. Additionally, high temperature extruders were included in the design to accommodate the printing requirements of both flexible and rigid filaments. Across 25 equally spaced points on the print plate, the maximum temperature difference between any two points on the heated bed was found to be ∼9°C for a target temperature of 170°C. With a uniform temperature profile across the plate, functional prints were achieved in each material. The print quality varied, dependent on material; however, the standard deviation of layer thicknesses and size measurements of the parts were comparable to those produced on a Zortrax M200 printer. After calibration and further process development, the custom printer will be integrated into the NEXUS system — a multiscale additive manufacturing instrument with integrated 3D printing and robotic assembly (NSF Award #1828355).
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Hadidi, Haitham, Brady Mailand, Tayler Sundermann, Ethan Johnson, Rakeshkumar Karunakaran, Mehrdad Negahban, Laurent Delbreilh, and Michael Sealy. "Dynamic Mechanical Analysis of ABS From Hybrid Additive Manufacturing by Fused Filament Fabrication and Shot Peening." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8253.
Анотація:
Abstract The mechanical properties of 3D printed polymers parts are process parameter dependent. Defects such as inadvertent voids between deposited rasters and layers lead to weakness in produced parts, which results in inferior mechanical properties as compared to injection molding. An alternative method to change energy absorption and stiffness of a polymer is hybrid additive manufacturing (AM). Hybrid-AM is the use of additive manufacturing with one or more secondary processes that are fully coupled and synergistically affect part quality, functionality, and/or process performance. In this study, fused filament fabrication (FFF) was coupled with layer-by-layer shot peening to study the dynamic mechanical properties of ABS 430 polymer using dynamic mechanical analysis (DMA). FFF is a heated extrusion process. Shot peening is a mechanical surface treatment that impinges a target with a stochastically dispersed, high velocity stream of beads. Compressive residual stress was imparted to preferential layer intervals during printing to modify the elasticity (stiffness), viscosity, toughness, and glass transition temperature. Viscoelastic and dynamic mechanical properties are important to the performance of polymers in automotive, aerospace, electronics, and medical components. Coupling printing and peening increased the storage and loss moduli as well as the tangent delta. DMA results suggest that preferential layer sequences exist that possess higher elasticity and better absorb energy upon sinusoidal dynamic loading.
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Nixon, Jason R., and David I. Bigio. "Effects of Variable Fiber Microstructure in Composite Fused Filament Fabrication on Physical Properties Using High Aspect Ratio Short Fibers." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-51903.
Анотація:
Polymeric fused filament fabrication technology (FFF), a subfield within additive manufacturing (AM), is becoming a contender for the reintroduction of the small-scale manufacturing of customized consumer products to a mass-production dominated world market. However, before this technology can be widely implemented, there remain significant technological hurdles to overcome. One issue that has been addressed at great length in other traditional polymer manufacturing fields is the inclusion of fillers in the component for physical property enhancement or the introduction of entirely new properties to the matrix material. Experiments conducted in this study examined the inclusion of carbon microfibers (CMFs) into the matrix material prior to the printing process, and the effect of different processing parameters on the final filler structure of the composite parts post printing. Prior work on microstructural evolution during extrusion in a 3D printer has been conducted computationally to study the effects of extrusion rate, matrix rheology, and nozzle geometry on fiber orientation [1]. It was found that varying the nozzle geometry generated significantly different microstructures, and that the remainder of the parameters could be varied to fine-tune microstructural characteristics. Findings indicated that, by varying the nozzle geometry from a converging to a diverging conical section, microstructures ranging from axially oriented (with respect to the extrusion direction) to radially oriented are theoretically possible. Current work performed on extruders and FFF platforms indicates that during the extrusion process, fibers tend to align very closely to the axis of extrusion in shear flow (i.e. converging or straight dies). However, in some applications, this may not be the most effective filler structure for property enhancement, so there remains interest in exploring methodologies for fiber rotation during extrusion. For this study, CMFs and acrylonitrile butadiene styrene (ABS) were compounded using a 28mm fully-intermeshing co-rotating twin-screw (CoTSE) extruder. 3D printer feedstock was manufactured in-house. A range of concentrations from 0%wt to 15%wt fabricated and tested. Analysis of the feedstock indicated nearly axial fiber alignment post-manufacture. This feedstock was then used in a Lulzbot TAZ4 printer to manufacture composite tensile testing specimens. Printed composite properties were then identified and compared to neat ABS and bulk composite properties. It was found that using a purely converging die, highly aligned filler structures were produced (with respect to the bead laid by the printer). Using a diverging nozzle, more random filler structures were produced. Improvements in both intra-layer properties were observed using the diverging nozzle geometries to reorient fibers during extrusion. Property improvements were not found to be as high as longitudinal properties for highly aligned filler structures. Using insights gained through these experiments, we are currently working on exploring added functionality for the composites using different types of fillers as well as multi-scale filler combinations.
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Li, Bingjue, Andrew P. Murray, and David H. Myszka. "Designing Variable-Geometry Extrusion Dies That Utilize Planar Shape-Changing Rigid-Body Mechanisms." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46670.
Анотація:
This paper presents a kinematic synthesis methodology for planar shape-changing rigid-body mechanisms that addresses constraints arising in the design of variable-geometry polymer extrusion dies. Such a die is capable of morphing its orifice in order to create extrusions of non-constant cross section. A variable-geometry shape-changing die problem is defined by a set of design profiles of different shapes and arc lengths, which approximate various cross sections of the extrusion. The primary advantage of the presented methodology is addressing the need for bodies in the mechanism formed by fusing links in the shape-changing portion of the chain. Previous methodologies included such fused links, but only at the end of the synthesis process where revolute joints were seen to be underutilized. A new method is needed to control, or even eliminate the use of revolute joints in the shape-changing chain of rigid links. The result of this new work is an iterative method which generates an optimized morphing chain to best match the design profiles while minimizing the number of prismatic and revolute joints needed to do so. The additional variable-geometry design constraints also require a generalization to the definition of fixed-end profiles previously proposed, also allowing chain ends to be defined by prismatic joints on a fixed line of slide. A virtual-chain method is also proposed to solve closure problems caused by the reduction in the number of revolute joints.