Journal articles on the topic 'Extrusion'
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1
Ren, Zhong. "Comparison Study on the Effect of Traction Speed on the GAE and Traditional Extrusion Forming of Four-Lumen Plastic Micro-Catheter." Key Engineering Materials 881 (April 2021): 39–44. http://dx.doi.org/10.4028/www.scientific.net/kem.881.39.
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In this paper, the effect of traction speed on the four-lumen plastic micro-catheter (FLPMC) was numerically studied. Moreover, the numerical simulations of FLPMC based on two kinds of extrusions, i.e., traditional extrusion and gas-assisted extrusion were performed and compared. Numerical results show that with the increase of traction speed, the sizes of FLPMC for both extrusions all decrease. The sizes of FLPMC based on gas-assisted extrusion are sightly larger than those of the traditional extrusion. To ascertain the reasons, the flow velocities, pressure, shear stress and first normal stress difference distributions of melt based on both extrusions under two different traction speeds were obtained and compared. Results show that with the increase of traction speed under the fixed volume inlet flow rate, the radial flow velocities of melt at the outlet of die decrease but the axial flow velocities increase, which results in the decrease of the die swell at the outlet of die and the size shrinkage of exit face for the FLPMC based on both extrusions. However, for the gas-assisted extrusion, the axial velocities are larger, and the pressure, shear stress and first normal stress difference are far less than those of traditional extrusion, which results in the larger unit volume flow rate, then the sizes of cross-section face are larger than those of the traditional extrusion.
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Lu, W. L., Y. Wang, and Jin Tao Hai. "The Effects of Extrusion Ratio and Friction on Material Microstructures during Sandglass Extrusion Process." Materials Science Forum 551-552 (July 2007): 383–86. http://dx.doi.org/10.4028/www.scientific.net/msf.551-552.383.
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Sandglass extrusion is an ultrafine grain size method. Due to the repetitive and multiple extrusions, large strain can be accumulated and ultrafine grain size can be obtained. Some factors can affect the experimental results of sandglass extrusion, such as extrusion ratio, number of extrusion, extrusion temperature, friction and free space in mould cavity etc. These factors have different effects on material microstructures, properties and defects. In this paper, the effects of extrusion ratio and friction on material microstructures during sandglass extrusion process have been discussed and theory analysis and experimental results have been reported.
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Yang, Jun Ying, Bao Yun Song, Hai Shi Ning, and Rong Fu. "Microstructure of AZ31 Magnesium Alloy Produced by the CONFORM Process under Different Extrusion Wheel Velocities." Advanced Materials Research 189-193 (February 2011): 2609–12. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.2609.
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It is widely known that the continuous extrusion forming (CONFORM) process can produce ultra-long seamless products of various cross-sections for aluminum, copper and their alloys. In this paper, the continuous extrusion of AZ31 magnesium alloy is achieved. The effect of extrusion wheel velocity on microstructure of extrusions is investigated. The results indicate that grain refinement is realized during CONFORM process. As the extrusion wheel velocity increases, the grain size at the center of a cross section perpendicular to the extrusion direction of an extrusion increases, and the grain structure tends to become uniform in the surface region.
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Lu, W. L., Y. Wang, and Jin Tao Hai. "The Effects of Free Space in Mould Cavity on Sandglass Extrusion." Materials Science Forum 475-479 (January 2005): 2999–3002. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.2999.
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Sandglass extrusion is an ultrafine grain size method. Due to the repetitive and multiple extrusions, large strain will be accumulated and ultafine grain size can be obtained. There are some factors that can affect the experimental result of sandglass extrusion. Among these factors, free space in mould cavity is very important, which can affect the forming of the fold during the extrusion. In this paper, the effects of free space in mould cavity on sandglass extrusion have been discussed and theory analysis and experimental results have been reported.
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Kim, Tae Bum, Masakazu Tane, Shinsuke Suzuki, Takuya Ide, Hiroshi Utsunomiya, and Hideo Nakajima. "Improvement of Strength of Lotus-Type Porous Aluminum through ECAE Process." Materials Science Forum 695 (July 2011): 263–66. http://dx.doi.org/10.4028/www.scientific.net/msf.695.263.
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Lotus-type porous aluminum with cylindrical pores oriented in one direction was deformed by Equal Channel Angular Extrusion (ECAE) through a 150° die with sequential 180° rotations, and the pore morphology and Vickers hardness after the extrusion were investigated. The Vickers hardness increases with increasing number of passes in the extrusions both parallel and perpendicular to the pore direction, accompanied by the decrease of porosity. The densification occurs more easily in the perpendicular extrusions than in the parallel extrusions, and the large deformation by the densification gives rise to the large increase in the Vickers hardness for the perpendicular extrusions.
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Zhao, Xiao Lian, Ning Ning Zhao, and Na Chen. "Effect of Extrusion Size on Forming Process in Equal Channel Angular Pressing." Applied Mechanics and Materials 275-277 (January 2013): 2171–75. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.2171.
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In order to meet the industrial demands for large-sized bulk ultrafine-grained materials, which were prepared by severe plastic deformation, the law curves of equivalent strain, equivalent stress and load of different-sized extrusions had been gotten by the finite element simulation of ECAP. The extrusion size has little effect on the values and distribution law of equivalent strain as well as the values of equivalent stress. With the increase of extrusion size, the distribution uniformity of equivalent stress decreases, and the extrusion load increases. Although the ECAP of the large-sized extrusions improve the requirements of mold and equipment, the chunk of evenly ultrafine-grained materials can be obtained by multiple passes.
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Jiang, Qifeng, Ramdane Boulahia, Fahmi Zaïri, Iurii Vozniak, Zhengwei Qu, Jean-Michel Gloaguen, and Xiaobing Liu. "Microstructure and Mechanical Properties of Severely Deformed Polypropylene in ECAE (Equal Channel Angular Extrusion) via Routes A and C." Polymers 14, no. 23 (December 3, 2022): 5287. http://dx.doi.org/10.3390/polym14235287.
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Equal channel angular extrusion (ECAE) is a solid-state extrusion process for modifying microstructures via severe plastic deformation without modifying the specimen cross section. In this study, changes in the microstructure and mechanical properties of polypropylene resulting from extrusion orientation route A (no rotation between extrusions) and extrusion orientation route C (a rotation of 180° between extrusions) are investigated using a 90° die-angle tooling outfitted with back pressure. Important differences are reported for the ECAE-induced deformation behavior between the two processing routes. A focus is made on the occurrence of heterogeneous plastic deformations (periodic shear banding and warping) for both routes and the control and inhibition of the plastic instabilities via regulated back pressure and ram velocity. Wide-angle X-ray scattering is carried out to characterize the structural evolution as a function of the processing conditions including route, extrusion velocity and BP application. The mechanical properties of the specimens machined from the ECAE pieces are examined under different loading paths including uniaxial tension/compression and simple shear. Full-field displacements converted to volumetric strains revealed the profound impacts of the processing route on the deformation mechanisms during tensile deformation.
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Xue, Yong, Zhi Min Zhang, and Li Hui Lang. "Effect of Forward Extrusion and Heat Treatment on Microstructure and Mechanical Properties of as-Cast ZK60 Magnesium Alloy." Advanced Materials Research 148-149 (October 2010): 332–37. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.332.
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In the present research, the influences of different extrusion ratios (15, 30, 45, 60, and 75), extrusion temperatures (300 , 340 , 380 , 420 , and 460 ), and subsequent heat treatment on the mechanical properties and microstructure of as-cast ZK60 magnesium alloy have been investigated through the tensile tests and via metallographic observation. The results show that forward extrusion process can refine the microstructure of as-cast ZK60 alloy effectively. If as-cast ZK60 alloys have been extruded with the extrusion ratio 45 at 380 ,420 and 460 , respectively, and then post-heat treatment was conducted, the ZK60 alloy’s strength is higher under T5 than T6 treatment. For as-cast ZK60 alloy processed by extrusion and T5 method, the most appropriate temperature for extrusion processing is 300 , at which its tensile strength are highest provided the extrusion ratio is 30 but yet its plasticity is best provided the extrusion ratio is 45. If forward extrusions were conducted at 380 , mechanical properties of ZK60 alloy have little difference as the extrusion ratio varies. When T6 treatment was conducted for the extruded bars, their mechanical properties were improved little, moreover, the bigger the extrusion ratio is, the higher the tensile strength and elongation of the extruded bars become.
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Bocato, Jessica Rico, Flávia Maria Cheffer Nory, Josimar Rosa Francisco, Ana Claúdia de Castro Ferreira Conti, Thais Maria Freire Fernandes, Marcio Rodrigues de Almeida, Renata Rodrigues de Almeida Pedrin, and Paula Vanessa Pedron Oltramari. "Interdisciplinary Orthodontic Treatment to Reestablishment Smile Function and Aesthetics." Journal of Health Sciences 22, no. 3 (September 20, 2021): 167–72. http://dx.doi.org/10.17921/2447-8938.2021v22n3p167-172.
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AbstractExtrusive tooth movements are an important resource in orthodontic treatment and allow the manipulation of teeth and periodontal tissues. They can be performed quickly or slowly, depending on the patient’s need. Rapid extrusion is indicated for cases in need of prosthetic preparation or restoration, where the bone and gingival tissues are intact, such as horizontal and oblique fractures, coronary or external root resorption, iatrogenic perforations (trepanations) and the presence of subgingival caries. The aim of this study is to describe the treatment of a patient who had a coronary fracture of the right upper central incisor, with a limit located 1 mm above the level of the bone crest. Rapid orthodontic extrusion was performed, to restore biologic distances and allow the preparation for prosthesis. It started with partial differentiated bonding of a fixed orthodontic appliance to the upper arch, to allow for a 3mm orthodontic extrusion. At the end of the extrusion, periodontal surgery was performed to increase the clinical crown and endodontic treatment. After these procedures, the case was concluded with the fixed prosthesis installation. The realization of an integrated planning allowed the restoration of aesthetics, with preservation of the functional periodontal limits for the patient. Keywords: Tooth Movement Techniques. Orthodontic Extrusion. Crown Lengthening. ResumoOs movimentos dentários extrusivos constituem um recurso importante no tratamento ortodôntico e permitem a manipulação dos dentes e dos tecidos periodontais. Eles podem ser realizados de forma rápida ou lenta, dependendo da necessidade do paciente. A extrusão rápida está indicada para casos com necessidade de preparo protético ou restauração, onde os tecidos ósseo e gengival encontram-se íntegros, tais como fraturas horizontais e oblíquas, reabsorções coronárias ou radiculares externas, perfurações iatrogências (trepanações) e presença de cárie subgengival. O objetivo deste trabalho é descrever o tratamento de uma paciente que apresentava fratura coronária do incisivo central superior direito, com limite localizado 1mm acima do nível da crista óssea. Realizou-se extrusão ortodôntica rápida, com a finalidade de restabelecer as distâncias biológicas e permitir o preparo para prótese. Iniciou-se com colagem diferenciada parcial de aparelho ortodôntico fixo no arco superior, para permitir a extrusão ortodôntica de 3mm. Ao término da extrusão, realizou-se cirurgia periodontal para aumento da coroa clínica e tratamento endodôntico. Após esses procedimentos, o caso foi finalizado com a instalação da prótese fixa. A realização de um planejamento integrado permitiu o restabelecimento da estética, com preservação dos limites periodontais funcionais para a paciente.Palavras-chave: Técnicas de Movimentação Dentária. Extrusão Ortodôntica. Aumento da Coroa Clínica.
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Uetani, Yasuhiro, Ryotaro Nagata, Hidetoshi Takagi, Kenji Matsuda, and Susumu Ikeno. "Effect of Granule Size in Semi-Solid Slurry on Rheo-Extrusion of A7075 Aluminum Alloy." Materials Science Forum 561-565 (October 2007): 291–94. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.291.
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Rheo-extrusions of A7075 aluminum alloy were carried out utilizing semi-solid slurries with different solid granule sizes, which were made by a simple method combined a thin upright tube with a water-cooled tube. Every structure of slurries was granular and average solid granule sizes could be controlled by 0.05 to 0.11mm. These slurries were extruded to round bars at extrusion ratio of 36 and press ram speed of 10mm/s mainly, just after cooling to 833K ( fs > 0.9 ). All of the slurries could easily be extruded to bars with smooth surfaces at much low extrusion forces than those of hot-extrusions. Tensile strength of rheo-extruded bars after solution treatment increased with decreasing of the solid granule size. Peak hardness level at T6 condition equivalent to that of hot-extrusion could be obtained at the finest solid granule size.
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Lee, Dae-Hee. "Incidence and Extent of Graft Extrusion following Meniscus Allograft Transplantation." BioMed Research International 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/5251910.
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Background. The incidence and extent of graft extrusion after meniscus allograft transplantation (MAT) may differ in patients undergoing medial and lateral meniscus transplantation due to the use of different surgical techniques. This meta-analysis was therefore designed to quantify the extent and incidence of graft extrusion after meniscus allograft transplantation. Methods. Following preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, all studies reporting absolute extrusion, relative percentage of extrusion (RPE), or frequency of major extrusions (>3 mm) on magnetic resonance imaging in patients undergoing medial or lateral MAT were included. Results. The pooled mean absolute extrusion following all MATs was 3.15 mm but was significantly greater following medial than lateral MAT (3.26 versus 3.01 mm; p=0.001). The pooled mean RPE following all MATs was 32.79% and was significantly greater after medial than lateral MAT (32.69% versus 28.81%; p<0.001). The pooled mean proportion of knees with major (>3 mm) extrusion was 53% (95% CI: 49% to 58%) and was significantly greater after medial than lateral MAT (61% versus 39%; p<0.001). Conclusion. Mean graft extrusion after arthroscopic assisted MAT using bony fixation was 3.2 mm, with major graft extrusion > 3 mm occurring in about 50% of transplanted menisci. Graft extrusion was significantly greater after medial than lateral MAT.
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Ren, Zhong, and Xing Yuan Huang. "Numerical Comparisons on the Effects of Wall Thickness on Extrudate Swell of Traditional Extrusion and Gas-Assisted Extrusion for Plastic Microtubules." Materials Science Forum 956 (June 2019): 253–59. http://dx.doi.org/10.4028/www.scientific.net/msf.956.253.
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In this study, the effect of wall thickness on the extrudate swell of plastic microtubules was investigated by using the finite element numerical method. For the traditional extrusion and gas-assisted extrusion, under the same process parameters, the extrudate swell ratios of plastic microtubules with the different wall thicknesses were all obtained. Moreover, to analyze the difference between the traditional extrusion and gas-assisted extrusion, the physical fields distributions, such as flow velocities, pressure and the stresses distributions of plastic microtubules with the different wall thicknesses under two kinds different extrusions were also obtained and compared. Numerical results show that, for the traditional extrusion, the extrudate swell ratio decreases with the increasing of the wall thickness, but for the gas-assisted extrusion, the swell ratios are equal to 0 and not changed. In addition, from the viewpoints of physical fields distributions, for the traditional extrusion, with the increasing of the wall thickness, the velocities, pressure and stresses of melt are all decreased, which result in the reducing of the extrudate swell phenomenon. However, for the gas-assisted extrusion, the X velocity, pressure, and stresses are all equal to 0, which results in the elimination the extrudate swell phenomenon of plastic microtubules.
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Aoki, Koshiro, Akira Azushima, and Yoshiyuki Kondo. "Fatigue Property of High-Strength Carbon Steel Deformed by Repetitive Side Extrusion Process." Materials Science Forum 475-479 (January 2005): 245–48. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.245.
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The development of an ultrafine grained carbon steel during repetitive shear deformation of side extrusion and the properties after heat treatment were investigated. Side extrusions were carried out at room temperature and the used material was 0.50% carbon steel. The repetitive side extrusions with a constant lateral pressure were carried out up to 3 passes without rotation. The specimens of these steels after 3 passes were annealed at a constant temperature of 600°C changing the treatment time. After side extrusion and heat treatment, the fatigue property was better than that of the as-received material.
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Ganapathy, Aravindh S., Myron S. Powell, and James L. Pirkle. "Extrusion of both Superficial and Deep Cuffs of a Functional Double-Cuff Peritoneal Dialysis Catheter after Significant Weight Loss." Case Reports in Nephrology and Dialysis 11, no. 2 (July 9, 2021): 190–94. http://dx.doi.org/10.1159/000515049.
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Extrusion of the superficial cuff of a peritoneal dialysis (PD) catheter is an uncommon complication that may be associated with infection or malfunction. However, extrusion of both the superficial and deep cuffs of a double-cuff catheter is rare and uniformly associated with failure and peritonitis. We report a case of a presternal-type PD double-cuff catheter with extrusion of both cuffs through an abdominal exit site after 6 years of use that has remained functional, which has not been previously reported. In this case, the patient had achieved a 60-kg weight loss resulting in retraction of the subcutaneous tissue around both cuffs, while the catheter was held in place by the titanium connector between the presternal extension tubing and the inner, coiled catheter. In such special circumstances, extrusion of both cuffs may not necessitate urgent catheter removal. A review of the literature revealed previous cases of superficial cuff extrusions with catheters remaining functional but not with deep cuff extrusion.
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Carneiro, Olga S., Júlio C. Viana, and João M. Nóbrega. "Processing-Microstructure-Properties Relationships in Extrusion of Thermoplastics." Materials Science Forum 514-516 (May 2006): 833–37. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.833.
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In this work, a rectangular polypropylene profile was produced with several different extrusion conditions, in order to identify the most relevant processing variables determining its morphology and mechanical properties and to establish relationships between them. A Taguchi Design of Experiments (DOE) technique considering two levels for each variable (extrusion temperature, extrusion throughput, drawdown ratio and distance between the die and the cooling bath) defined the set of extrusions runs carried out. The resulting plastic profiles were characterized in terms of their microstructure and mechanical properties. It was concluded that the most significant processing variable determining the mechanical properties of the profiles is the extrusion temperature and that the drawdown ratio controls the degree of molecular orientation of the profile and, therefore, the extension of its shrinkage after heatiing.
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Zhang, Xiaohui, Xingyuan Huang, Bin Liu, and Shuiquan Chen. "Study on the Melt Rheological Characterization of Micro-Tube Gas-Assisted Extrusion Based on the Cross-Scale Viscoelastic Model." Polymers 16, no. 7 (April 3, 2024): 973. http://dx.doi.org/10.3390/polym16070973.
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In the micro-tube gas-assisted extrusion process, flow theories ignoring cross-scale viscoelastic variations fail to effectively characterize the rheological state of the melt. To investigate the impact of cross-scale viscoelastic variation on the quality of the micro-tube gas-assisted extrusion, a 3D multiphase flow extrusion model incorporating a double gas-assisted layer was developed. Subsequently, we modified the DCPP constitutive equations based on the cross-scale factor model. Both the traditional and gas-assisted extrusions were simulated under macroscale and cross-scale models using the Ansys Polyflow. Finally, using the established gas-assisted extrusion platform, extrusion experiments were conducted. The results indicate that, owing to the reduced melt viscosity under the cross-scale model, the deformation behavior of the melt is more pronounced than in the macroscale model. The cross-scale model’s numerical results more closely match the experimental outcomes under the same parameters, thereby confirming the feasibility of the theoretical analysis and numerical simulation. Moreover, the predictive capability of the cross-scale model for the micro-tube gas-assisted extrusion is further validated through numerical and experimental analyses with varying parameters. It is demonstrated that the cross-scale viscoelastic variation is a critical factor that cannot be overlooked in the gas-assisted extrusion.
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Zhang, Kai, Knut Marthinsen, Bjørn Holmedal, Jesper Friis, Tanja Pettersen, and Antonio Segatori. "Characterization and Modelling of the Microstructure and Texture Evolution in AlMgSi-Extrusions." Materials Science Forum 879 (November 2016): 1239–44. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1239.
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The properties and surface appearance of aluminium extrusion are critically dependent on the microstructure and texture of the extruded profiles, and the requirements with respect to these aspects may vary with applications. Moreover it is often a challenge to produce extrusions with a consistent and homogenous grain structure and texture along as well as through the cross section of the profiles. It is thus vital to understand and be able to predict (model) how different microstructures and textures are formed and how they evolve during and after extrusion. In the present work a model framework has been implemented which includes a FEM model to account for the strain, strain rate and temperature along a set of particle paths during extrusion. From these the deformation texture and grain structure are calculated with an appropriate deformation texture model and a sub-structure evolution model, respectively. The sub-structure model have in the present work been coupled to a crystal plasticity model to provide an orientation dependent subgrain size and dislocation density during deformation which provides the driving force for the post-extrusion recovery and possible recrystallization behaviour. The post-extrusion microstructure and texture evolution is calculated with a recovery and recrystallization model, which is accompanied by a recrystallization texture model. The framework and its constituent models and their interplay are presented, and some preliminary results when applying this modelling framework to Al-Mg-Si extrusions are presented and discussed in view of corresponding experimental results.
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Spoerk, Martin, Florian Arbeiter, Ivan Raguž, Clemens Holzer, and Joamin Gonzalez-Gutierrez. "Mechanical Recyclability of Polypropylene Composites Produced by Material Extrusion-Based Additive Manufacturing." Polymers 11, no. 8 (August 7, 2019): 1318. http://dx.doi.org/10.3390/polym11081318.
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Due to a lack of long-term experience with burgeoning material extrusion-based additive manufacturing technology, also known as fused filament fabrication (FFF), considerable amounts of expensive material will continue to be wasted until a defect-free 3D-printed component can be finalized. In order to lead this advanced manufacturing technique toward cleaner production and to save costs, this study addresses the ability to remanufacture a wide range of commercially available filaments. Most of them either tend to degrade by chain scission or crosslinking. Only polypropylene (PP)-based filaments appear to be particularly thermally stable and therefore suitable for multiple remanufacturing sequences. As the extrusion step exerts the largest influence on the material in terms of temperature and shear load, this study focused on the morphological, rheological, thermal, processing, tensile, and impact properties of a promising PP composite in the course of multiple consecutive extrusions as well as the impact of additional heat stabilizers. Even after 15 consecutive filament extrusions, the stabilized additively manufactured PP composite revealed an unaltered morphology and therefore the same tensile and impact strength as the initial material. As the viscosity of the material of the 15th extrusion was nearly identical to that of the 1st extrusion sequence, the processability both in terms of extrusion and FFF was outstanding, despite the tremendous amount of shear and thermal stress that was undergone. The present work provides key insights into one possible step toward more sustainable production through FFF.
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Noguchi, Akinori. "Extrusion Cooking." JSM Mycotoxins 67, no. 1 (2017): 33–42. http://dx.doi.org/10.2520/myco.67-1-2.
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Foydl, Annika, Insa Pfeiffer, Matthias Kammler, Daniel Pietzka, Thorsten Matthias, Andreas Jäger, A. Erman Tekkaya, and Bernd Arno Behrens. "Manufacturing of Steel-Reinforced Aluminum Products by Combining Hot Extrusion and Closed-Die Forging." Key Engineering Materials 504-506 (February 2012): 481–86. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.481.
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Aluminum matrix composite extrusions reinforced with wires made of high strength stainless steel represent an innovative material concept for lightweight structures. The use of reinforcing elements should improve the mechanical properties and the performance of lightweight structures. This study deals with the process chain of extrusion and die forging to manufacture steel-reinforced products. The production of discontinuously-reinforced, semi-finished aluminum profiles by co-extrusion is in focus on the extrusion part. The material flow is analysed in order to understand, and further to influence, where the steel-reinforcements are appear in the strand. For the forging part the extruded profiles are continuous-reinforced by means of steel wires as well as partially by means of steels elements. For the process design the geometry of the forging die cavity and the material flow are of vital importance. A Finite Element Analysis is carried out in order to predict the position of the elements in the forging parts depending on the position in the extrusions.
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Wang, Tianhao, Bharat Gwalani, Joshua Silverstein, Jens Darsell, Saumyadeep Jana, Timothy Roosendaal, Angel Ortiz, Wayne Daye, Tom Pelletiers, and Scott Whalen. "Microstructural Assessment of a Multiple-Intermetallic-Strengthened Aluminum Alloy Produced from Gas-Atomized Powder by Hot Extrusion and Friction Extrusion." Materials 13, no. 23 (November 25, 2020): 5333. http://dx.doi.org/10.3390/ma13235333.
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An aluminum (Al) matrix with various transition metal (TM) additions is an effective alloying approach for developing high-specific-strength materials for use at elevated temperatures. Conventional fabrication processes such as casting or fusion-related methods are not capable of producing Al–TM alloys in bulk form. Solid phase processing techniques, such as extrusion, have been shown to maintain the microstructure of Al–TM alloys. In this study, extrusions are fabricated from gas-atomized aluminum powders (≈100–400 µm) that contain 12.4 wt % TM additives and an Al-based matrix reinforced by various Al–Fe–Cr–Ti intermetallic compounds (IMCs). Two different extrusion techniques, conventional hot extrusion and friction extrusion, are compared using fabricating rods. During extrusion, the strengthening IMC phases were extensively refined as a result of severe plastic deformation. Furthermore, the quasicrystal approximant IMC phase (70.4 wt % Al, 20.4 wt % Fe, 8.7 wt % Cr, 0.6 wt % Ti) observed in the powder precursor is replaced by new IMC phases such as Al3.2Fe and Al45Cr7-type IMCs. The Al3Ti-type IMC phase is partially dissolved into the Al matrix during extrusion. The combination of linear and rotational shear in the friction extrusion process caused severe deformation in the powders, which allowed for a higher extrusion ratio, eliminated linear voids, and resulted in higher ductility while maintaining strength comparable to that resulting from hot extrusion. Results from equilibrium thermodynamic calculations show that the strengthening IMC phases are stable at elevated temperatures (up to ≈ 600 °C), thus enhancing the high-temperature strength of the extrudates.
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Ye, Sixian, Huangjun Zhou, Xingyu Lyu, Hao Feng, Min Liu, and Cai Wen. "Should the vent hole of posterior implant crowns be placed on the lateral surface? An in vitro study of the hydrodynamic feature of cement extrusion and retention ability." PLOS ONE 17, no. 10 (October 20, 2022): e0276198. http://dx.doi.org/10.1371/journal.pone.0276198.
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Although placing a vent hole on the occlusal surface of the implant crown can reduce cervical marginal cement extrusion, it has disadvantages. Transferring the hole to the buccal or lingual surface of the posterior implant crown could therefore be an alternative solution. This study investigated the effect of transferring the vent hole to the lateral side of the implant posterior crown on the hydrodynamics of excess cement extrusion and the crown’s retention ability. Specially fabricated posterior implant crowns were divided into five groups: crowns with an occlusal hole (OH), occlusal lateral hole (OLH), middle lateral hole (MLH), cervical lateral hole (CLH), and no hole (NH). Each set of implant analog-abutment-crown specimens was wrapped in a polymethylacrylate base. The base of the implant crown was divided into four 90-degree quadrants along the diagonal of the square base with a pen mark. Cement was used to bond the crowns and the abutments, and the weight of cement extrusions at the vent holes and the abutment cervical margins were calculated. The distribution of cement extrusion at the margin was photographed in each quadrant, and the areas of surface coverage of cement extrusion were compared with ImageJ software. Retentive strength was measured as the dislocation force using a universal testing machine. One-way analysis of variance was used for result analysis. The cervical marginal cement extrusions of crowns with lateral holes (OLH, MLH, and CLH) were significantly less than that of NH crowns (P<0.05), but more than that of OH crowns (P<0.05). Subgroup analysis among the lateral hole groups indicated that the higher the position of the lateral hole, the lower the weight of the cement extrusion, and the smaller the total distribution area of cement extrusion. The cement extrusion distribution area was larger in the quadrant with the hole than in those opposite and next to the hole. Retention strength comparison indicated no significant difference between crowns with NH, OH, or lateral holes. Transferring the vent hole of the posterior implant crown to the lateral side could reduce cement extrusion at the cervical margin while reducing retention strength deterioration and the esthetic drawbacks caused by occlusal hole opening.
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Sriram, S., and C. J. Van Tyne. "Criterion for Prevention of Central Bursting in Forward Extrusions Through Spherical Dies Using the Finite Element Method." Journal of Manufacturing Science and Engineering 124, no. 1 (February 1, 2001): 65–70. http://dx.doi.org/10.1115/1.1413776.
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Spherical dies are increasing in popularity in the cold-forming industry because of the ease in subsequent secondary operations. This paper presents criteria curves, calculated using the finite element method, to avoid central bursting or internal chevrons in forward extrusions through spherical dies. Critical values of mean stress at the centerline of the extrusion are used as failure criteria to distinguish between acceptable and unacceptable die designs. These failure criteria are conservative in that the critical step for central bursting is considered to be the formation of a microvoid during extrusion, rather than linking of the voids during continued deformation. The resulting process criteria curves are conservative estimates of internal chevron formation during extrusion through spherical dies.
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Zhou, Ming, Jianyong Cao, Fulin Yu, and Xia Wei. "Evaluation of Magnesium Extrusion Production." Materials Science Forum 488-489 (July 2005): 483–86. http://dx.doi.org/10.4028/www.scientific.net/msf.488-489.483.
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Compared with any other pressure processing methods, extrusion is more prone to develop the plasticity of the metal. Extrusions have much better size precision and surface quality than products by rolling and forging. As one-shot molding process, extrusion can eliminate some machining. In addition, extrusions have very high strengths and elongations because of their compact interior structures and fine grains. This paper summarizes some experiences and plans in extrusion production of CQMST(Chongqing Magnesium Science & Technology Co.Ltd). Magnesium, a plentiful element with density of 1.78g/cm3，2/3 of aluminum and 1/4 of steel, is characterized by its high specific strength and toughness, good dumping performance, thermal conductivity and electromagnetism shielding as well as recyclability. Following the advancing technologies of magnesium smelting, high pressure processing, surface treatment and soldering since 1990’s, the prices of magnesium and its ingot stepped down. As an important light engineering material, magnesium application is growing at annual speed of 15%, much higher than aluminum, copper, zinc, nickel and steel. In China, magnesium and magnesium alloy development, application and industrialization has been placed on the National “Tenth Five-year Plans” and the National “863” Scheme, which indicated the coming of new age for magnesium and magnesium alloy development and application in China. In the past, most of the magnesium products were produced by casting, especially die casting and thixomolding. It’s always considered that the crystal structure of magnesium is hexagonal close-packed, and only two slip planes exist at room temperature, so compared with other alloys, it’s very difficult to produce magnesium parts by forging, rolling or extrusion. Nevertheless, practice showed that if heated to a certain temperature, magnesium extrusion may not be hard work, and even easier than 5056 and 2024 aluminum. When extruded with distributary die, magnesium alloy can have better soldering performance than aluminum alloys mentioned above, just because new slip system forms along with increasing temperature (>225°C) and accordingly increases the plasticity of magnesium.
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Kaczor, Daniel, Krzysztof Bajer, Aneta Raszkowska-Kaczor, Grzegorz Domek, Piotr Madajski, and Pawel Szroeder. "The Influence of Multiple Extrusions on the Properties of High Filled Polylactide/Multiwall Carbon Nanotube Composites." Materials 15, no. 24 (December 15, 2022): 8958. http://dx.doi.org/10.3390/ma15248958.
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High filled polylactide/multiwall carbon nanotube composites were subjected to multiple extrusions using single-screw and twin-screw extruders. Samples of the processed composites were characterized by SEM, XRD, Raman, and FTIR spectroscopy. Thermal and rheological properties were investigated by DSC and MFR analyses. Subsequent extrusions resulted in decreased torque and process efficiency, which is a consequence of the viscosity reduction of PLA. Thermal and rheological properties of composites changed after each extrusion as well. As revealed by DSC analyses, cold crystallization temperature showed a tendency to decrease after each process, whereas cold crystallization enthalpy ΔHcc increased significantly. Melt flow rate, which is indicative of the polymer degradation, increased after each extrusion.
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Lukban, James C., Roger D. Beyer, and Robert D. Moore. "Incidence of Extrusion Following Type I Polypropylene Mesh “Kit” Repairs in the Correction of Pelvic Organ Prolapse." Obstetrics and Gynecology International 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/354897.
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Introduction and Hypothesis. We sought to determine the mesh extrusion (vaginal exposure) rates and subject outcomes following IntePro (Type I polypropylene) mesh “kit” repairs for vaginal prolapse.Methods. Data were pooled from two prospective multicenter studies evaluating the safety and efficacy of the Perigee and Apogee (American Medical Systems, Minnetonka, Minn, USA) to treat anterior and posterior/apical prolapses, respectively. Extrusions involving the anterior compartment (AC) or posterior compartment/apex (PC/A) were recorded.Results. Two hundred sixty women underwent mesh placement, with a total of 368 mesh units inserted (173 in the AC and 195 in the PC/A). Extrusions were noted in 13 (7.5%) of AC implants and 27 (13.8%) of PC/A implants through 12 months. No difference was seen between those with and without extrusion in regard to anatomic cure, postoperative painor quality of life at 1 year.Conclusions. Extrusion had no apparent effect on short-term outcomes. Given the unknown long-term sequellae of vaginal mesh exposure, a thorough assessment of risks and benefits of transvaginal mesh placement should be considered at the time of preoperative planning.
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Lin, T. H., S. R. Lin, and X. Q. Wu. "Micromechanics of an Extrusion in High-Cycle Fatigue With Creep." Journal of Applied Mechanics 57, no. 4 (December 1, 1990): 815–20. http://dx.doi.org/10.1115/1.2897646.
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Extrusions and intrusions often are sites of fatigue cracks. The extent of extrusions is important in fatigue crack initiation. Metals often are subject to fatigue loadings at elevated temperatures. At temperatures below one half of the melting temperature slip is the main mechanism of inelastic deformation. In this study, an aluminum polycrystal loaded in this temperature range is considered. A most favorably oriented crystal located at a free surface of a f.c.c. polycrystal subject to creep under cyclic tension and compression of high-cycle fatigue is considered. An extrusion in this crystal is shown to be produced by a positive slip in one thin slice “P” and a negative slip in a closely located slice “Q”. An initial tensile strain εααI in the thin slice “R” sandwiched between P and Q causes a positive initial shear stress ταβI in P and a negative one in Q. It is shown that the extrusion growth causes a tensile strain in R, which can activate a second slip system giving a creep strain with a tensor component εαα. It has the same effect as the initial strain εααI in causing this difference in shear stresses in P and Q and gives much additional extrusion growth. The extent of intrusion and extrusion is important in this study of crack initiation.
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Valberg, Henry. "Extrusion welding in aluminium extrusion." International Journal of Materials and Product Technology 17, no. 7 (2002): 497. http://dx.doi.org/10.1504/ijmpt.2002.001317.
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KAMEDA, HIROSHI. "Rubber Extrusion. Formulation of Extrusion." NIPPON GOMU KYOKAISHI 69, no. 5 (1996): 365–74. http://dx.doi.org/10.2324/gomu.69.365.
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Wilson, Robert, Nigel A. Stone, and Mark A. Gibson. "Extrusion of CP Grade Titanium Powders Eliminating the Need for Hot Pre-Compaction via Hot Isostatic Pressing." Materials Science Forum 534-536 (January 2007): 801–4. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.801.
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Extrusion is a way to produce near net shape components from CP grade titanium powders of optimum density with minimum porosity and acceptable mechanical properties. Chemically pure, hydride/dehydride titanium powders were cold pre-compacted and extruded at 850oC under an argon atmosphere. The extrusion stress required was ~450MPa. To characterize the extrusions, the porosity distribution, qualitative microstructure and tensile properties were evaluated and compared with conventional extruded wrought titanium. Extrusion occurred after the green billets were upset to ~100% of theoretical density and adequate lubrication was applied to the die. The resultant product was 100% dense with a narrow band of surface porosity and exhibited an equiaxed microstructure of similar magnitude to the starting material. The tensile properties of the bars were observed to be significantly superior to conventionally extruded CP titanium bar products, a result associated with the much finer average grain size. Outcomes from this study have assisted in the identification of a number of key characteristics important to the extrusion of titanium from pre-compacted CP titanium powders, allowing the elimination of canning and hot isostatic pressing (HIPping) of billets prior to extrusion as per conventional PM processes.
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Aravas, N., and R. M. McMeeking. "An Asymptotic Analysis of Three-Dimensional Extrusion." Journal of Applied Mechanics 56, no. 3 (September 1, 1989): 519–26. http://dx.doi.org/10.1115/1.3176121.
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A new method of analysis of three-dimensional metal extrusion using asymptotic perturbation methods is presented in this paper. The plasticity model used depends on the first and second invariants of the stress tensor and covers a wide range of constitutive models commonly used for the analysis of metal-forming operations. It is shown that the three-dimensional extrusion problem can be approximated, to leading order, by a problem of generalized plane-strain. The results of the asymptotic analysis together with the finite element method are used to obtain approximate solutions for extrusions of elliptic or square cross-sections from round billets.
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Fathy, A., M. Abdelhameed, and F. Shehata. "Effect of Some Manfacturing Parameters on Machining of Extruded Al-Al2O3 Composites." ISRN Materials Science 2012 (April 17, 2012): 1–6. http://dx.doi.org/10.5402/2012/748734.
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A wide range of particulate metal matrix composites (PMMCs) of alumina and aluminum powders was formed using powder metallurgy techniques followed by extrusions at various extrusion ratios. The machining characteristics of the extruded PMMC were investigated. Results showed significant effects of weight fractions of reinforcement and extrusion ratios on tool wear and surface integrity of machined surface. The wear rate of cutting tool decreased rapidly with increasing the cutting parameters: cutting speed, feed, and depth of cut, however cutting speed is shown to be more effective. Sudden breakage of tool inserts occurred when the experiment started at high cutting speed. Wear rate has also decreased by decreasing volume fraction of reinforcement particles. Coating carbide tools have significantly improved the tool life. Coated tools showed 5% decrease in flank wear size compared to uncoated tools. This was valid within tested range of weight fractions and extrusion ratios. The surface finish of machined surfaces deteriorated when coated carbide tools were used. However, surface finish did not change significantly when volume fractions or extrusion ratios were altered.
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Kartha, S., K. Young, and S. Mohan. "Complications of Medialization Laryngoplasty (Thyroplasty Type-I)." International Journal of Phonosurgery & Laryngology 1, no. 1 (2011): 1–3. http://dx.doi.org/10.5005/jp-journals-10023-1001.
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ABSTRACT Objective Medialization laryngoplasty (formally type 1 thyroplasty) is an accepted treatment for unilateral vocal fold paralysis or paresis. The objective of this paper is to ascertain the complications following medialization laryngoplasty in patients with particular reference to implant extrusion. Study design The records of 85 patients who underwent medialization laryngoplasty were retrospectively reviewed from January 2001 to July 2009. Results There were 3 implant extrusions noted only in female patients with cartilage removal technique. Conclusions Implant extrusion rate following medialization laryngoplasty in our institution is comparable to published literature.
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Kirkham, Chris, Joe Cartwright, Claudia Bertoni, and Pieter Van Rensbergen. "The genesis of a giant mud canopy by catastrophic failure of a thick evaporite sealing layer." Geology 48, no. 8 (May 12, 2020): 787–91. http://dx.doi.org/10.1130/g47430.1.
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Abstract Three-dimensional seismic imaging and well calibration reveal a large allochthonous mud edifice that is composed of several mud extrusions and covers an area >740 km2 on the outer shelf slope of the Nile Delta. The allochthonous material was sourced from beneath the ∼1-km-thick Messinian evaporites in the Eastern Mediterranean and extruded synchronously as eight large mud volcanoes directly on top of the Messinian evaporites in a catastrophic remobilization event at the end of the Messinian salinity crisis. These large extrusive flows coalesced to form a single edifice with an exceptional volume of ∼292 km3 that is connected to eight widely spaced conduits. We argue that this large mud body represents a new morphological type and scale of mud extrusion. We propose that mud extrusions that coalesce on a surface forming a multi-conduit-fed edifice be referred to as mud canopies, by analogy with salt canopies, with implications for basin reconstruction, paleo–overpressure release events, and fluid migration.
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Tanaka, Tatsuya. "Extrusion." Seikei-Kakou 21, no. 7 (June 20, 2009): 361–70. http://dx.doi.org/10.4325/seikeikakou.21.361.
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Shiromoto, Seiji. "Extrusion." Seikei-Kakou 22, no. 7 (June 20, 2010): 326–32. http://dx.doi.org/10.4325/seikeikakou.22.326.
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Tanoue, Shuichi. "Extrusion." Seikei-Kakou 18, no. 9 (September 20, 2006): 669. http://dx.doi.org/10.4325/seikeikakou.18.669_1.
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Tanaka, Tatsuya. "Extrusion." Seikei-Kakou 20, no. 7 (July 20, 2008): 375–85. http://dx.doi.org/10.4325/seikeikakou.20.375.
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Kim, Hanwook, Seong-Il Bin, Jong-Min Kim, Bum-Sik Lee, and Dong-Wook Sohn. "Progression of Allograft Extrusion in Both the Coronal and Sagittal Planes at Midterm Follow-up After Medial Meniscal Allograft Transplant." Orthopaedic Journal of Sports Medicine 9, no. 2 (February 1, 2021): 232596712097235. http://dx.doi.org/10.1177/2325967120972351.
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Background: Although many studies have examined allograft extrusion after medial meniscal allograft transplant (MMAT), it is unclear whether allograft extrusion progresses at midterm follow-up. Hypothesis: After MMAT, allograft extrusion would not progress during the midterm follow-up period. Study Design: Case series; Level of evidence, 4. Methods: A total of 30 patients who underwent MMAT between December 1996 and March 2016 were enrolled. Allograft extrusion was measured on magnetic resonance imaging scans obtained at 6 weeks, 1 year, and 3 to 7 years postoperatively. In the coronal plane, the absolute allograft extrusion and relative percentage of extrusion were measured. In the sagittal plane, the absolute and relative anterior cartilage meniscal distance and posterior cartilage meniscal distance were measured. The joint-space width (JSW) on radiographic Rosenberg view was measured at 3 time points. The axial alignment was measured preoperatively and at the midterm follow-up. Results: In the coronal plane, there were no significant differences in absolute and relative coronal extrusions between 6 weeks and 1 year postoperatively; however, the values were significantly increased at midterm follow-up compared with both of the earlier follow-up periods. Similarly, in the sagittal plane, the mean absolute and relative anterior and posterior cartilage meniscal distances were not significantly different between 6 weeks and 1 year postoperatively but showed significant increases at midterm follow-up compared with both of the earlier follow-up periods. The mean preoperative axial alignment showed a positive correlation with the delta value of relative percentage of extrusion in the coronal plane ( r = 0.378; P = .036). The mean JSW was 4.42 ± 0.88 mm preoperatively, 4.30 ± 0.83 mm at 1-year follow-up, and 3.96 ± 1.06 mm at the midterm follow-up. No significant difference was found between the preoperative and postoperative 1-year values, but the mean JSW was significantly decreased at midterm follow-up compared with both of the other time points ( P = .001 for both). Conclusion: Allograft extrusion did not progress until 1 year after MMAT; however, by midterm follow-up, extrusion had progressed in both the coronal and the sagittal planes. Preoperative axial alignment showed a positive correlation with allograft extrusion in the coronal plane.
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Beygelzimer, Y., D. Prilepo, R. Kulagin, V. Grishaev, O. Abramova, V. Varyukhin, and M. Kulakov. "Planar Twist Extrusion versus Twist Extrusion." Journal of Materials Processing Technology 211, no. 3 (March 2011): 522–29. http://dx.doi.org/10.1016/j.jmatprotec.2010.11.006.
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Peng, Zhi, and Terry Sheppard. "Prediction of Static Recrystallisation after Extrusion of Shaped Aluminium Sections." Materials Science Forum 467-470 (October 2004): 407–20. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.407.
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Extrusions experience large deformations at discontinuities when they traverse the die land, leading to considerable modifications to the average deformation parameters when compared to the remainder of the extrusion. The distribution of structure is therefore greatly inhomogeneous. Reference to both empirical and physical models of the recrystallisation process indicate that nucleation and growth will differ at these locations in those alloys that are usually solution treated and aged subsequent to the deformation process. Since static recrystallisation has a significant influence on many of the properties of the extrudate, it is therefore essential to provide the methodology to predict these variations. In the work presented, a physical model based on dislocation density, subgrain size and misorientation is integrated into the commercial FEM codes, FORGE2® and FORGE3® to study the microstructure changes. Axi-symmetrical and shape extrusion are presented as examples. The evolution of the substructure influencing static recrystallisation is studied. The metallurgical behaviour of axi-symmetric extrusion and that of shape extrusion are compared. The predicted results show good agreement with experimental measurement. The distribution of equivalent strain, temperature compensated strain rate and temperatures are also presented to aid in interpretation.
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Manosalvas Quiroz, Luis Armando, Clara Elena Villacrés, and Richard Taimal. "Efecto de la humedad de alimentación y temperatura de extrusión sobre el contenido nutricional de un snack a base de maíz, chocho y papa." Revista Bases de la Ciencia. e-ISSN 2588-0764 4, no. 3 (December 31, 2019): 67. http://dx.doi.org/10.33936/rev_bas_de_la_ciencia.v4i3.1911.
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Los efectos de diferentes parámetros operativos de extrusión en equipos de un solo tornillo sobre los cambios nutricionales del snack fueron estudiados. Los parámetros de extrusión investigados fueron: temperatura del barril (110 – 140ºC), contenido de humedad (15% - 20%) y matriz alimentaria: maíz (Zea mays), chocho (Lupinus mutabilis Sweet) y papa (Solanum tuberosum) en proporción 80/10/10 y 70/15/15 (p/p). Los snacks que registraron mayor contenido nutricional fueron con la matriz en proporción 70/15/15 a 15% de humedad y extruida a 110°C, con valores de humedad 6.06%, proteína 18.69%, grasa 2.01%, fibra 2.28%, cenizas 1.00% y carbohidratos 72.24%, con relación al tratamiento control, (100% maíz) que registró contenidos de humedad de 5.13%, proteína 8.32%, grasa 0.54%, fibra 0.55%, cenizas 0.57% y carbohidratos 85.44%. Las condiciones de extrusión aplicadas en este estudio mostraron efectos significativos sobre el contenido nutricional del snack extruido obtenido. El incremento del nivel de adición/sustitución de leguminosas y tubérculos a la matriz con maíz, mejora significativamente el contenido nutricional del producto extruido.
Palabras clave: extrusión, matriz alimentaria, humedad, temperatura, snack.
Abstract
The effects of different extrusion operational parameters in one screw equipments on the nutritional changes of the snack were studied. The studied extrusion parameters were: barrel temperature (110 - 140ºC), moisture content (15% - 20%) and food matrix: corn (Zea mays), lupine (Lupinus mutabilis Sweet) and potato (Solanum tuberosum) in proportions 80/10/10 and 70/15/15 (w/w). The highest nutritional content reported was for the 70/15/15 w/w food matrix snacks at 15% of humidity and extruded at 110°C, which resulted with 18.69% of protein , 2.01% of fat, 72.24% of carbohydrates,2.28% of fiber, 1.00% of ashes and 6.06% of moisture with respect to control snacks (100% corn) which reported a nutritional analysis of 8.32% of protein, 0.54% of fat, 85.44% of carbohydrates, 0.55% of fiber, 0.57% of ashes and 5.13% of moisture. The extrusion conditions applied in this study showed significant effects on the extruded snack obtained. The increase of the addition/substitution level of legumes and tubers in the corn matrix, significantly improves the extruded product nutritional content.
Keywords: extrusion, moisture, temperature, snack, food matrix.
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Jha, Shilpa, Kate Atkinson, Matthew R. McFegan, Amit Patel, Alexandros Vris, Nima Heidari, Lee Parker, Luckshmana A. Jeyaseelan, and Francesc Malagelada Romans. "Assessment of Midterm Functional Outcomes Following Talar Extrusion Injuries." Foot & Ankle Orthopaedics 7, no. 1 (January 2022): 2473011421S0026. http://dx.doi.org/10.1177/2473011421s00266.
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Category: Ankle; Hindfoot; Trauma Introduction/Purpose: Open talar dislocations with complete or partial extrusion of the talus are rare, high energy injuries associated with major complications including infection, avascular necrosis and post-traumatic arthritis. These are debilitating injuries with significant long-term effects including avascular necrosis and post traumatic arthritis. Functional outcome data in the literature is limited and predominantly consists of case reports and few single centre case series. Historically these injuries have been treated with talectomy and tibiocalcaneal arthrodesis, however there has been a subsequent trend towards debridement and reimplantation with preservation of the extruded talus. Our aim was to evaluate mid-term functional outcomes, assess complication profile and need for secondary surgery in a single-centre series of cases treated with reimplantation. Methods: All talar extrusion injuries presenting between January 2015 and January 2018 were identified from the trauma database search at our major trauma centre. Inclusion criteria was defined as open talar dislocations associated with either complete or partial extrusion of the talus. Case-note review was performed collecting baseline demographic data including age, gender, injury mechanism, associated injuries, Gustilo-Anderson grade, smoking and diabetes status, and method and timing of surgical management. Twelve patients were identified with a mean follow-up of 3 years (minimum 26 months). Primary outcome measure was functional outcome assessed using the Manchester-Oxford Foot Questionnaire (MOxFQ). Results for each of the three domains were converted to a 0-100 scale for comparison. Secondary outcomes included complication rate and all cause re- operation rates Results: Mean age was 37.8 years (17-74 years). Five patients (42%) had total talar extrusion without fracture and 7/12 (58%) sustained fracture-dislocation with partial talar extrusion. All were Gustilo-Anderson grade III. All underwent successful reimplantation with 8/12 (67%) treated with single stage surgery, and 4/12 (33%) in two stages. The mean MOxFQ scores for total talar extrusions versus partial talar extrusions with fracture were 79 (range 9-18) vs 41 (range 0-86) for walking domain, 65 (range 45-80) vs 42 (range 0-90) for pain domain, and 63 (range 38-75) vs 48 (range 19-51) for social domain. One patient (8%) developed avascular necrosis, 3/12 (25%) developed infection and 1/12 (8%) patient eventually required below knee amputation. One (8%) patient underwent secondary surgery fusion for post-traumatic arthritis. Conclusion: Our series demonstrates the serious ramifications of sustaining talar extrusions. Patients who sustain these injuries should expect persistent functional deficit and pain at mid-term follow-up. Functional outcomes are relatively poor. The data demonstrates a trend towards better functional outcomes in patients who have partial extrusion of the talar dome with associated fractures, compared to ligamentous total talar extrusion injuries. The incidence of avascular necrosis, deep infection and secondary surgery in our cohort supports reimplantation as an effective treatment strategy.
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SCHREK, Alexander, Branislav VANKO, and Pavol SEJČ. "FORMING OF A BIMETALLIC ELEMENT FOR THE RESISTANCE ELEMENT SOLDERING METHOD." Journal of Metallic Materials 74, no. 2 (November 29, 2022): 8–20. http://dx.doi.org/10.32730/imz.2657-747.22.2.2.
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The joining of sheet metal parts produced in the material combination of Fe-Fe, Fe-Al as well as Fe-thermoplastic and Al-thermoplastic can be realized by the Resistance Element Soldering (RES). Extruded bimetallic elements were used to form the overlap joint. The semi-finished product for extrusions was a Cu 99.9 tube with dimensions φ6 × 0.5 mm and length 9 mm, filled with Sn60Pb40 solder. “T” shaped overprints were produced in two ways. Simulation in the ANSYS software environment was chosen to optimize, select the appropriate forming process, and design the geometry of the functional parts of the forming tool, allowing to use only one extrusion forming operation. The results of the simulations are the magnitudes of stresses and strains, and different head shape geometries of the bimetallic element extrusions of the three proposed forming methods. The task was to achieve extrusions without defects of the Cu tube shell, such as corrugations and wrinkles. The geometry was observed and compared by macroanalysis of extrusion sections made on a laboratory forming tool.
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Laohachaiaroon, Pratchawin, Bancha Samruajbenjakun, and Ekachai Chaichanasiri. "Initial Displacement and Stress Distribution of Upper Central Incisor Extrusion with Clear Aligners and Various Shapes of Composite Attachments Using the Finite Element Method." Dentistry Journal 10, no. 6 (June 20, 2022): 114. http://dx.doi.org/10.3390/dj10060114.
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A clear aligner is an esthetic and more comfortable option for patients who need orthodontic treatment. However, some types of tooth movement, such as extrusion, are difficult with this tool. Therefore, composite attachments have been suggested to improve tooth movement. This study aims to evaluate the initial displacement and stress distribution during upper central incisor extrusion using the conventional composite attachments. Maxillary models with the upper teeth, clear aligners, and composite attachments placed on the labial surface of the upper right central incisor were constructed. Four models were created to simulate upper central incisor extrusion: (1) without any composite attachment; (2) rectangular beveled attachment; (3) ellipsoid attachment; and (4) horizontal rectangular attachment. Clear aligners were designed to perform upper central incisor extrusion. The constructed models were analyzed using the finite element method. Initial displacement and stress distribution were analyzed. Output analysis found that the upper right central incisor in the model with a horizontal rectangular attachment had the greatest extrusive movement, followed by the model with ellipsoid attachment and the model with beveled attachment. Maximum compressive stress was seen at the cervical region of the composite attachment. Composite attachments including horizontal rectangular attachment, ellipsoid attachment, and rectangular beveled attachment can be used to perform upper central incisor extrusion.
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Patel, Yashwant Kumar. "EXTRUSION TECHNOLOGY: AN EFFICIENT TECHNOLOGY IN FOOD PROCESSING." International Journal of Multidisciplinary Research Configuration 2, no. 4 (October 28, 2022): 01–20. http://dx.doi.org/10.52984/ijomrc2401.
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Extrusion technology is an efficient method of producing varieties of new food products with minimal loss of nutrients. It is a food processing technique that integrates numerous unit activities such as mixing, heating, kneading, shearing, shaping, and forming into a single process. Food extrusion is a type of extrusion that is used in the food processing industry. It is a procedure in which a mixture of materials is driven through an aperture in a perforated plate or die with a food-specific pattern, and then cut to size by blades. The extruder is the machine that drives the mixture through the die, and the mixture is known as the extrudate. The extruder is made out of a big revolving screw that is firmly fitted into a stationary barrel, with the die at the end.This paper focuses on the operational practises used in the food processing business as well as their effects on various foods and their physiochemical properties. Extrusion processing is significant in food processing because it is used to make pasta, textured vegetable protein (TVP), ready-to-eat cereal snacks, baby meals, morning cereals, dietary fibre, pet foods, cereal-based modified starch, and conventional items. Extrusion cooking aids in the inactivation of enzymes and lowers microbial activity, Because of the high temperature, extrusions have an influence on the quality of food items. The most significant influence is on nutritional and physio-chemical characteristics. Because of the forward shifting of chemical structure, nature of protein, carbohydrates, and other elements. Extruded products are manufactured using many types of extruders. Key-words: Extrusion, minimal processing technology, extruded products, ready-to-eat cereal snacks, and HTST.
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Schwartz, Michal, Dan Gheorghe, Robert Ciocoiu, and Ion Ciucă. "Die Failures in Copper Hot Extrusion." Advanced Materials Research 1114 (July 2015): 56–61. http://dx.doi.org/10.4028/www.scientific.net/amr.1114.56.
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Low life service of steel dies used in copper extrusion brought us to inspect several discarded copper hot extrusion dies in order to identify failures and failure mechanisms. The investigations performed are mainly hardness tests and microscopic investigations. The profiles extruded are circular, rectangular and hexagonal. It was observed that die design is not at fault; rather the die material is to blame for low life service of the tool. Discarded extrusion dies after copper hot extrusions were investigated. The failure of the dies was first observed by naked eye and the observations recorded. From the dies the ones with most plastic deformations and obvious signs of failure were selected. An improvement in die design could expand the service life, but our main concern is the material: a balance between toughness and hot strength is critical, yet this balance is hard to achieve. Other thermal processing of the die is still in question and investigations are currently being performed. At least an increase of tool service life could be achieved by thermal processing of the material to a state prior nanometric carbide precipitation between martensitic plates.
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Horrobin, D. J., and R. M. Nedderman. "Extrusion Pressure Estimation in Axisymmetric Paste Extrusion." KONA Powder and Particle Journal 17 (1999): 122–29. http://dx.doi.org/10.14356/kona.1999019.
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Bouaziz, Amira, Marwa khemakhem, Valérie Massardier, and Mohamed Jaziri. "The effect of extrusion reprocessing cycles on the structure and properties of nano-silica reinforced polypropylene/ethylene-propylene-rubber composites." Journal of Composite Materials 52, no. 30 (May 24, 2018): 4219–30. http://dx.doi.org/10.1177/0021998318777863.
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In this study, the effect of repeated extrusion processing cycles on the structure and properties of polypropylene/ethylene-propylene-rubber/nano-silica composites was investigated. The recycling process was simulated by performing three extrusion runs, using a high shear twin screw extruder by varying the speed screw rotation (300, 800, and 1200 r/min), in order to get better understanding of the multi recycling effects. For comparative purposes, neat polypropylene/ethylene-propylene-rubber was also reprocessed under the same conditions as a reference material. From the morphological analyses performed by scanning electron microscopy, multiple extrusions were found to be not only helpful for decreasing the ethylene-propylene-rubber phase size, but also useful for ensuring a more homogenous dispersion of silica nanoparticles within the matrix. The physico-chemical properties analyses illustrate that the repeated cycles of extrusion processing provoke a decrease of the molar masses and an increase in the melt flow index. It was marked that, when going from the 1st to the 2nd extrusion cycle, and by increasing the rotation speed from 300 to 800 r/min at the same cycle, the mechanical properties were greatly enhanced. A substantial improvement of these properties was achieved after incorporating the silica nanoparticles and the maleic anhydride grafted polyethylene copolymer.
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Štípek, Jan, Jan Skočilas, Jaromír Štancl, and Rudolf Žitný. "Extrusion rheometry of collagen dough." Czech Journal of Food Sciences 39, No. 5 (October 14, 2021): 384–92. http://dx.doi.org/10.17221/265/2020-cjfs.
Full textAbstract:
Although collagen is widely used (for example, in the food industry, in the pharmaceutical industry and in biomedicine), the rheological properties of the material are not well known for high concentrations (8% collagen, 90% water). Rheological properties were measured using a capillary-slit rheometer (an extrusion process), where the tested sample of collagen matter was pushed by a hydraulically driven piston through a narrow rectangular slit at very high shear rates of 50–6 000 s<sup>–1</sup>. The Herschel-Bulkley (HB) constitutive equation and a new correlation taking into account the finite gap width was used to evaluate the rheological properties (n = 0.2, K = 879 Pa s<sup>n</sup>, τ<sub>0</sub> = 2 380 Pa). Use was made of a new yield stress measurement method evaluating τ<sub>0</sub> 'post mortem' after extrusion stops. The effects of wall slip and of air bubbles, which caused apparent compressibility of the 'silly putty' collagen material, were also studied. Corrections of the wall slip effect were implemented using sliding layer thickness δ.