Relevant bibliographies by topics / Extrusion defects

Academic literature on the topic 'Extrusion defects'

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Published: 4 June 2021
Last updated: 13 February 2022

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Journal articles on the topic "Extrusion defects"

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Polák, Jaroslav, and Jiří Man. "Cyclic Slip Localization and Crack Initiation in Crystalline Materials." Advanced Materials Research 891-892 (March 2014): 452–57. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.452.

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Cyclic plastic straining in crystalline materials is localized to persistent slip bands (PSBs) and results in formation of persistent slip markings (PSMs) consisting of extrusions and intrusions. Intensive plastic strain in PSBs results in dislocation interactions and formation of point defects. The extended model based on point defect formation, migration and annihilation is presented describing surface relief formation in the form of extrusion-intrusion pairs. Point defect migration and resulting mass transfer is the principle source of cyclic slip irreversibility leading to crack-like defects - intrusions. Fatigue cracks start in the tip of sharp intrusions.
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Zhu, H., Carlos H. Cáceres, Xin Quan Zhang, Malcolm J. Couper, and Arne K. Dahle. "Investigation of Streaking Defects on Aluminium Extrusions." Materials Science Forum 561-565 (October 2007): 341–44. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.341.

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The presence of surface defects, such as streaking, is one of the most serious quality issues for 6000-series aluminium extrusions. The formation of a streaking defect near a web intersection of a hollow profile was investigated in detail. The streak was apparent on the extrusion in both the as-extruded and the as-anodised conditions. Microstructural examinations indicate that the streaked region contains different surface imperfections compared to the normal region and smaller grains and stronger texture than the normal region. The effects of die design and microstructural variables on the formation of streaks on aluminium extrusions are discussed.
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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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Zhu, Han Liang, Xin Quan Zhang, Malcolm J. Couper, and Arne K. Dahle. "Classification of Streaking Defects on Anodized Aluminium Extrusions." Materials Science Forum 618-619 (April 2009): 349–52. http://dx.doi.org/10.4028/www.scientific.net/msf.618-619.349.

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Streaking is a common problem on anodised extrusions of 6xxx series soft alloys. This paper presents various types of streaking defects on the basis of industry practice and experimental results. The streaking defects are classified according to their root causes. This provides a basis for developing effective methods for preventing the formation of these defects for the extrusion.
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Leder, M. O., I. Yu Puzakov, N. Yu Tarenkova, M. A. Kornilova, and K. A. Rusakov. "Revisited: gas-saturated defects in titanium alloys." MATEC Web of Conferences 321 (2020): 10007. http://dx.doi.org/10.1051/matecconf/202032110007.

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The simulation results of the internal defects generated during deformation by extrusion and rolling are presented herein. It was demonstrated that end-type deformation defects can result in the formation of internal gas-saturated defects not cropping out the surface under the specific deformation conditions. Key characteristics of the generated defects similar to those of the production defects that have been previously classified as metallurgical are determined. Key words: defect, deformation, discontinuity.
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Prakash, Om. "Defects in multilayer plastic films I: Interface defects in extrusion." Computational Materials Science 37, no. 1-2 (August 2006): 7–11. http://dx.doi.org/10.1016/j.commatsci.2005.12.039.

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Pathania, Mallika, Elena V. Semina, and Melinda K. Duncan. "Lens Extrusion fromLaminin Alpha 1Mutant Zebrafish." Scientific World Journal 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/524929.

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We report analysis of the ocular lens phenotype of the recessive, larval lethal zebrafish mutant,lama1a69/a69. Previous work revealed that this mutant has a shortened body axis and eye defects including a defective hyaloid vasculature, focal corneal dysplasia, and loss of the crystalline lens. While these studies highlight the importance of lamininα1 in lens development, a detailed analysis of the lens defects seen in these mutants was not reported. In the present study, we analyze the lenticular anomalies seen in thelama1a69/a69mutants and show that the lens defects result from the anterior extrusion of lens material from the eye secondary to structural defects in the lens capsule and developing corneal epithelium associated with basement membrane loss. Our analysis provides further insights into the role of the lens capsule and corneal basement membrane in the structural integrity of the developing eye.
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Morsi, K., H. B. McShane, and M. McLean. "Processing defects in hot extrusion reaction synthesis." Materials Science and Engineering: A 290, no. 1-2 (October 2000): 39–45. http://dx.doi.org/10.1016/s0921-5093(00)00932-1.

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HARRISON, P. J., J. M. NEWTON, and R. C. ROWE. "Flow defects in wet powder mass extrusion." Journal of Pharmacy and Pharmacology 37, no. 2 (February 1985): 81–83. http://dx.doi.org/10.1111/j.2042-7158.1985.tb05011.x.

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Zhao, De Ying, Lian Dong Zhang, and Li Na Sun. "Forming Mechanism of Folding Defect within Closed Die Forming Car Steering Knuckle." Materials Science Forum 704-705 (December 2011): 240–44. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.240.

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Steering knuckle is the key part of vehicle steering system. The forming technology combined closed die pre-forging with open finish-forging has some advantages such as higher material utilization ratio and lower forming forces and so on. While simulating the closed die extrusion forming process of car steering knuckle, folding defect emerges on the contact area of Branch I and lower punch in the lateral extrusion process. The forming mechanism of the folding defect is studied by numerical simulations and experiments, which mainly consider the influence of lower punch shape and size, extrusion speed and friction conditions to folding length. The results show that the main factors that affect folding defects are the lower punch shape and size. Keywords: steering knuckle, folding defect, closed die forming, numerical simulation, experiment study
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Dissertations / Theses on the topic "Extrusion defects"

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Amarasinghe, Angodage Don Upul Shantha. "Interpretation of paste extrusion data." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285008.

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Clode, Michael Paul. "The origin of defects during Al-Mg-Si extrusion." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/8084.

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Peiti, Christian. "Modification des propriétés rhéologiques des polymères branchés par traitement thermomécanique : application aux défauts d'extrusion des PEBD." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00820611.

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L'objectif de cette thèse est d'observer la modification du comportement rhéologique dedifférents polyéthylènes branchés, suite à un traitement de cisaillement. Après avoir décrit lesmatériaux et les moyens utilisés, nous avons caractérisé le plus complètement possible lecomportement rhéologique des différents matériaux, aussi bien en cisaillement qu'en élongation.Nous avons également déterminé des données calorimétriques et des informations sur lescaractéristiques moléculaires, permettant entre autres de définir la masse entre enchevêtrements.Nous avons ensuite mesuré l'évolution de la viscosité dans différentes conditions de pré‐cisaillement,en faisant varier le temps et le taux de cisaillement dans un rhéomètre cône‐plan et dans unegéométrie de Couette montée en amont d'un rhéomètre capillaire. Nous avons montré que lesmécanismes de désenchevêtrement sont complexes et qu'ils ne sont pas directement explicables parun seul paramètre, comme la masse entre enchevêtrements. Enfin, l'observation des extrudats à lasortie de la filière nous a permis de mettre en évidence la modification des défauts d'extrusion sousl'effet d'un pré‐cisaillement.
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Yrieix, Marie. "Impact du couplage charges / matrice sur les propriétés rhéologiques de nanocomposites silice / élastomère : application aux défauts volumiques d’extrusion." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES035/document.

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La structure et les propriétés rhéologiques de nanocomposites élastomère (BR ou SBR)/silice ont été étudiées dans cette thèse dans le but de mieux comprendre, par la suite, l’origine des défauts volumiques qui peuvent être observés à l’extrusion de ces mélanges. Des mélanges modèles simplifiés ont été réalisés au laboratoire et majoritairement étudiés dans ce travail de thèse. La structure de ces nanocomposites a été caractérisée par des mesures de taux d’élastomère lié, des analyses en RMN ainsi que des observations microscopiques (MEB ou MET). Ces dernières ont souligné l’existence de microstructures similaires pour les mélanges à base de BR dans la gamme de températures et de vitesses de mélangeage étudiée. A première vue, l’absence de différence quant à la distribution ou la dispersion des charges suggère donc que les différences de propriétés rhéologiques résident davantage dans les interactions gomme/charges. Les analyses en RMN ont, quant à elles, permis la détermination des taux de greffage du silane incorporé aux mélanges pour coupler les charges aux chaines élastomères. Il a été observé qu’une augmentation de la température de mélangeage favorise le greffage du silane. Les analyses RMN ont également mis en évidence la présence de réactions de pré-réticulation. Les taux de greffage ont alors pu être reliés aux conditions de mélangeage, via l’établissement d’une loi corrélant les taux de greffage silane/BR à un paramètre d’équivalence temps-température. Ce dernier est représentatif de l’histoire thermique subie par le mélange lors de sa préparation. La structure des mélanges a été corrélée aux propriétés rhéologiques caractérisées par des mesures en rhéologie dynamique, en fluage et en élongation. Les temps de relaxation moyens ou l’indice de strain hardening « SHI », issus de ces mesures, ont montré une augmentation avec la croissance des taux de greffage déterminés en RMN. Ces comparaisons ont également mis en évidence l’impact de la vitesse de mélangeage dont l’augmentation tend à diminuer le rhéoépaississement. Il existe donc au cours du mélangeage une compétition entre les réactions de greffage et les phénomènes de rupture qui induisent respectivement une croissance ou une réduction de la taille des amas d’agrégats connectés ; ces derniers étant à l’origine de l’augmentation du rhéoépaississement. Un modèle rendant compte de cette compétition a été proposé afin d’estimer l’évolution du SHI en fonction du taux de greffage et de la vitesse de mélangeage. Pour finir, les propriétés rhéologiques ont été comparées aux défauts volumiques caractérisés par profilométrie. Cette comparaison a mis en évidence l’existence de lois uniques reliant ces descripteurs rhéologiques au niveau de bosselage
The structure and rheological properties of elastomer (BR or SBR)/silica nanocomposites were studied in this work in order to understand the causes of volume defects observed during blends extrusion. Simplified model blends were prepared in laboratory internal mixer and mainly studied in this work. Nanocomposites structure was characterized by bound rubber measurements, NMR analysis and microscopic observations (SEM or TEM). These last observations have highlighted the existence of similar microstructures for BR blends in the range of studied mixing temperature and speeds. At first sight, the absence of difference in the fillers distribution or dispersion suggests that silica/rubber interactions have main impact on rheological properties. NMR analysis allowed the determination of silane grafting rate. TESPT silane was incorporated in blends to couple fillers to elastomer chains. It has been observed that the mixing temperature increase promotes the grafting of the silane. NMR analysis also demonstrated the presence of pre-crosslinking reactions. Grafting rates were then connected to the mixing conditions, through the establishment of a law correlating the silane/BR grafting rate to a time-temperature equivalence parameter. This parameter is representative of the thermal history undergone by the blend during its preparation. Blend structure was correlated to rheological properties characterized by dynamical rheology, creep and elongation measurements. Relaxation times or strain hardening index "SHI", determined thanks to these measurements, increase with the growth of grafting rate. These evolutions have also highlighted the impact of the mixing speed on rheological properties. The increase of mixing speed tends to reduce the shear thickening. Therefore, a competition between the grafting reactions and breaking phenomena occurs during blending. Grafting and breaking phenomena respectively induce growth or reduction of the size of connected aggregates clusters. The latter are responsible of the increase in the strain hardening. A model accounting for this competition has been proposed to estimate the evolution of SHI as a function of grafting and mixing speed. Finally, rheological properties were compared to volume defects characterized by profilometry. This comparison showed the existence of unique laws correlating these rheological descriptors to the intensity of volume instabilities
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Zhu, Yijun. "Computational Approach to Defect Reduction in Hot Extrusion and Rolling with Material and Process Uncertainties." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259773708.

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Bondon, Arnaud. "Stabilité des écoulements stratifiés en coextrusion : Etude multi-échelle du rôle de l’architecture du copolymère aux interfaces." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0100.

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Le procédé de coextrusion permet de combiner à l’état fondu plusieurs couches de polymères dans une même structure. La compatibilisation des différentes couches est généralement réalisée à l’aide de liants qui réagissent in-situ. Bien que la compatibilisation puisse permettre de réduire ou même supprimer les instabilités macroscopiques d’écoulement, un nouveau défaut qualifié de « granité » peut apparaitre. Très peu de travaux de la littérature traitent les mécanismes gouvernant ce type de défaut. Les phénomènes mis en jeu sont particulièrement complexes puisqu’ils impliquent de façon couplée des phénomènes hydrodynamiques via l’écoulement, la rhéologie des différentes couches et des phénomènes physico-chimiques via la diffusion et la réaction chimique aux interfaces polymère/polymère. Ce mémoire s’articule autour d’une étude multi-échelle du rôle des copolymères aux interfaces sur la stabilité des écoulements stratifiés. L’étude a été réalisée à la fois sur des systèmes non-réactifs et réactifs constitués d’une couche barrière, le polyamide 6 (PA6) ou le poly(éthylène-co-alcool vinylique) (EVOH), avec un polypropylène (PP) ou un polypropylène greffé anhydride maléique (PP-g-AM). Le défaut de « granité » a été mis en évidence en coextrusion. Les paramètres procédé et matériaux influençant son apparition ont été identifiés. Il a pu être différencié des défauts et des instabilités interfaciales généralement rencontrées en coextrusion. Le phénomène de compatibilisation a également été étudié via les caractérisations morphologiques (MET, MEB, AFM) et physico-chimiques (XPS) aux interfaces. Le comportement rhéologique en cisaillement et élongation en viscoélasticité linéaire et non linéaire s’est révélé très sensible à l’effet la présence de copolymères aux interfaces et à leur architecture moléculaire. Cette étude a permis de déterminer les propriétés intrinsèques de l’interface/interphase en fonction du copolymère formé entre le liant et le PA6 ou l’EVOH. Elles ont pu être corrélées aux défauts macroscopiques observés dans les films multicouches coextrudés. La stabilité de ces écoulements stratifiés résulte d’un couplage de phénomènes qui se produisent à différentes échelles : nano (réaction de copolymérisation), micro (interphase) et macro (écoulement dans le procédé)
Several polymers can be combined in one multilayer structure by reactive coextrusion. Tie-layers are often used to compatibilize the adjacent layers and may reduce or suppress the interfacial instabilities and the defects in the multilayer coextrusion flow. However, an additional defect defined as the “grainy” defect can be observed. In the best of our knowledge, no study in literature has been devoted to understand its origin. The phenomena are quite complex due to the coupling of the effects of flow and the physico-chemical mechanisms at the interface. The aim of this work is to understand the relations between the instabilities and the defects encountered in multilayer coextruded films and the role of the copolymer formed in-situ between tie and barrier layers. Polyamide 6 (PA6) and ethylene-vinyl alcohol copolymer (EVOH) were used as the barrier layers sandwiched in a polypropylene (PP) with or without a polypropylene grafted maleic anhydride (PP-g-MA) as a tie-layer. The effect of the process parameters and the structure of the polymers on the generation of the “grainy” defect was assessed in correlation with the rheological and the physicochemical properties of the layers. These experiments have shown that this defect appeared mainly in the compatibilized EVOH system and could be distinguished from the usual coextrusion instabilities. The interfacial properties between tie and barrier layers were investigated. The characterization of the interfacial morphology by TEM and AFM highlighted an irregular and rough interface between PP-g-MA and EVOH while a flat interface was observed with PA6 and PP-g-MA. Step shear and startup elongation rheology was shown to be sensitive to the copolymer at the polymer/polymer interface. The study of the interfacial properties highlighted that the copolymer architecture significantly impacts the interfacial roughness and the rheology of the multilayer stuctures. Hence, relations between the relaxation process, the interfacial morphology and the copolymer architecture were established in correlation with the generation of the macroscopic grainy defect in coextrusion
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LI, WEN-SHUN, and 李文舜. "The analysis of forming defects in combination extrusion." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/snx528.

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碩士
國立高雄應用科技大學
模具工程系
106
Extrusion process has been broadly used in forming fastener products. There are forward and backward extrusions in its application. The so-called combination extrusion is when the two schemes are used concurrently. The metal flow tends to be complex and beyond prediction in the combination extrusion. Surface cracks and fracturing damage are phenomenal and to be discussed in this work. The die outlet angle and die radius are two essential design guidelines in achieving successful extrusion. However, proper selection of the extrusion ratios becomes essential when the product geometry contradicts the design guidelines. Surface cracks or even fracturing damage would occur when the selection of extrusion ratios violates the range for safe forming. In this study, annealed ASTM A36 structural steel bar with a diameter of 25 mm and a height of 25 mm was used to investigate the forming defects of combination extrusion. Finite element software DEFORM-2D axisymmetric was used for the analysis. The normalized Cockcroft and Latham, Ayada, McClintock and Rice & Tracy damage criteria were used to predict the occurrence of forming defects. The forward extrusion ratio ranged from 1.33 to 4.00 and the backward extrusion ratio ranged from 1.20 to 4.00. The results of simulation were subsequently verified with experiments. The distribution of mean stress was also used to help explain the discrepancies between the damage prediction and experimental verification. The result shows that the damage criteria of Ayada and McClintock can roughly predict the piercing defects of the combination extrusion, except for a small forward extrusion ratio of 1.33. However, the distribution of mean stress can well predict the piercing defect. The piercing mechanism is similar to that of hole punching in sheet stamping. The four damage criteria and mean stress distribution cannot predict well enough for the occurrence of surface cracks. However, Ayada and McClintock damage criteria predict for somehow better than the rest of the two other criteria. Finally, a forming limit chart was constructed from the results of the combination-extrusion experiment. This chart contains three zones namely “safe forming”, “surface cracks” and fracturing damage. The trend shows that safe forming appears when both the forward extrusion ratio (FER) and backward extrusion ratio (BER) are large. Surface cracks occur when both FER and BER are reduced. The cracks would occur at the inner surface of the backward extruded cavity when the FER is less than the BER during the late stage of combination-extrusion. However, the cracks would occur at the outer surface of the forward extruded shaft when the FER is larger than the BER during the early stage of combination-extrusion. Fracturing damage occurs when both FER and BER are further reduced. It starts from the inner corner of the backward extruded cavity to the outer corner of the forward extruded shaft when the FER is less than the BER. Moreover, fracturing damage would start reversely when the FER is larger than the BER. Forming loads tend to be low when fracturing damage occurs at small FER and BER. Crack propagates easily when the pressure of extrusion chamber is insufficient. Therefore, Cracks or fracturing damage would occur at the backward extruded part which corresponding to higher deformation when FER is less than BER. On the contrary, cracks or fracturing damage would occur at the forward extruded part which corresponding to higher deformation when FER is larger than BER. Forming loads would increase when both FER and BER are high. The safe forming would result because the tendency of crack propagates would be suppressed when the pressure of extrusion chamber increases.
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Lin, Shin-Yu, and 林星佑. "Study on formation of central bursting defects in extrusion processes." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/79360969473785487153.

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碩士
國立中山大學
機械與機電工程學系研究所
91
This paper describes a method by means of FE code DEFORMTM-2D to simulate the formation of central bursting defects in extrusion processes; the effect of various extrusion parameters such as half die angle, reduction in area, friction factor, and strain hardening exponent on the maximum damage value is examined. The differences between various ductile fracture criteria are compared and critical damage value(CDV) of the material AA6061 is found. In addition, we get the strength coefficient(K), strain hardening exponent(n), CDV and friction factor(m) by material tests, such as uniform tensile test, notched tensile test, compression test, and ring compression test. Finally, the cold multistage extrusion experiment was conducted to verify the accuracy of the finite element simulations. From the continuous three pass extrusion experimental data, no fracture in the center of the extruded product was found. From the analytical data, it was known that the maximum damage value 1.0479 for third pass extrusion was small than critical damage value 1.068, thus, central bursting defects didn’t occur in extrusion processes.
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Hung, Chen-Chieh, and 洪振傑. "The central bursting defects analysis of conical axisymmetric extrusion by rigid-plastic boundary approach." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/13478480832000095164.

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Cheng-Tsung, Wu, and 吳正琮. "The improvement of the piercing and surface-crack defects in combination-extrusion of support pin." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/45j96u.

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碩士
國立高雄應用科技大學
模具系碩士在職專班
105
Extrusion process has been broadly used in forming fastener products. There are forward extrusion and backward extrusion for this process. The so-called combination extrusion is used when the two operations are applied at the same time. Proper extrusion ratios are essential for the combination extrusion process. Improper selections of extrusion ratio lead to piercing or surface crack defects. This work aims to improve the piercing or surface crack defects occurred in forming support pins with combination extrusion. It focuses on the modification of the third stage for the guiding pre-form and the fourth stage for the combination extrusion. The measures include: (1) At the third stage, the depth of the circular pit is increased and let the forward extruded part contact the ejector. This would initiate the onset of the backward extrusion and increase the hydrostatic pressure in the billet. The tendency for surface crack and piercing is thus suppressed. (2) At the fourth stage, the combination extrusion is split into forward and followed by backward extrusion, or backward and followed by backward extrusion. The result from the DEFORM simulation and tool trial shows that: (1) Method 1 causes an increase of strain in the workpiece. This is attributed to the increase of deformation. The dead metal in the vicinity of the punch contact interface also decreases. The workpiece transits from the piercing to the forming modes. The damage value also increases due to this transition. This calls for the further investigation on this issue. The tool trial also verifies the feasibility of the method. (2) Method 2 also causes an increase in the workpiece, attributed to the increase of deformation. The distribution of strain evolves from concentrating in the piercing line to the round corners, causing the transition from the piercing to the forming mode. The dispersion of the strain concentration also reduces the damage value. The tool trial also verifies the feasibility of the method. The forming quality is better with the forward followed by backward extrusion method attributed to less amount of dead metal occurrence in the vicinity of the punch contact interface. Keywords: combination extrusion, piercing defect, surface-crack defect, fastener forming
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Book chapters on the topic "Extrusion defects"

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Antonelli, D., and A. Barcellona. "Effectiveness of Numerical Simulation in Avoiding Defects in Hot Extrusion Forging Products." In AMST ’99, 353–60. Vienna: Springer Vienna, 1999. http://dx.doi.org/10.1007/978-3-7091-2508-3_38.

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Zhu, H., C. H. Caceres, Xin Quan Zhang, Malcolm Couper, and Arne K. Dahle. "Investigation of Streaking Defects on Aluminium Extrusions." In Materials Science Forum, 341–44. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-462-6.341.

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Babaniaris, Steven, Aiden Beer, and Matthew R. Barnett. "The Influence of Process Parameters and Themomechanical History on Streaking Defects in AA6060 Extrusions." In Light Metals 2017, 371–77. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-51541-0_46.

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Ketata, M., A. Ayadi, Ch Bradai, and N. Elkissi. "Effect of the Radial Flow and Average Molecular Weight on the Surface Defect in PDMS Extrusion." In Design and Modeling of Mechanical Systems—III, 623–29. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-66697-6_60.

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Ketata, M., A. Ayadi, Ch Bradai, and S. Ben Nasrallah. "Effect of the Radial Flow on the Volume Defect in Polydimethylsiloxane Extrusion Using PIV the Technique." In Design and Modeling of Mechanical Systems—III, 911–18. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-66697-6_89.

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Chen, F. X., He Jun Li, J. Q. Guo, and X. Z. Liu. "The Pilot Study on the Defect Prediction and Numerical Simulation in the Superplastic/ Extrusion of Copper Alloy." In Superplasticity in Advanced Materials, 293–96. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-435-9.293.

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"Extrusion of Soft- and Medium-Grade Alloys." In Aluminum Extrusion Technology, 149–86. ASM International, 2000. http://dx.doi.org/10.31399/asm.tb.aet.t68260149.

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Abstract This chapter discusses the extrusion characteristics of relatively soft aluminum alloys. It begins by identifying alloy designations within the class and the types of extrusions made from them. It then explains how extruded shapes and cross-sections are defined and how to analyze and assess important process variables such as runout, extrusion pressure, ram speed, and butt thickness. It also provides best practices for various operations and explains how to identify and remedy common extrusion defects.
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Bauser, Martin. "Metallurgical Principles." In Extrusion, 141–94. 2nd ed. ASM International, 2006. http://dx.doi.org/10.31399/asm.tb.ex2.t69980141.

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Abstract This chapter explains the basic terminology and principles of metallurgy as they apply to extrusion. It begins with an overview of crystal structure in metals and alloys, including crystal defects and orientation. This is followed by sections discussing the development of the continuous cast microstructure of aluminum and copper alloys. The discussion provides information on billet and grain segregation and defects in continuous casting. The chapter then discusses the processes involved in the deformation of pure metals and alloys at room temperature. Next, it describes the characteristics of pure metals and alloys at higher temperatures. The processes involved in extrusion are then covered. The chapter provides details on how the toughness and fracture characteristics of metals and alloys affect the extrusion process. The weld seams in hollow profiles, the production of composite profiles, and the processing of composite materials, as well as the extrusion of metal powders, are discussed. The chapter ends with a discussion on the factors that define the extrudability of metallic materials and how these attributes are characterized.
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"Extrusion of Hard Alloys." In Aluminum Extrusion Technology, 187–211. ASM International, 2000. http://dx.doi.org/10.31399/asm.tb.aet.t68260187.

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Abstract This chapter discusses the extrusion characteristics of hard aluminum alloys, particularly those in the 5000 and 7000 series. It begins with a review of two studies, one showing how the extrudability of 7xxx alloys varies with the presence and amount of different alloying elements, the other relating minimum wall thickness with circumscribing circle diameter. It then explains how oxides on either the billet or container complicate the control of extrusion as well as auxiliary processes and how material flow and the movement of trapped gasses in different regions of the extrusion can lead to defects and variations in strength. It also discusses the extrusion of aluminum matrix composites and explains how composite billets are made.
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"Billet Casting Principles and Practice." In Aluminum Extrusion Technology, 119–48. ASM International, 2000. http://dx.doi.org/10.31399/asm.tb.aet.t68260119.

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Abstract This chapter describes various aspects of the billet making process and how they affect the quality of aluminum extrusions. It begins with an overview of the direct-chill continuous casting technique and its advantages over other methods, particularly for hard aluminum alloys. It then discusses the influence of casting variables, including pouring temperature and cooling rate, and operating considerations such as the make-up of charge materials, fluxing and degassing procedures, and grain refining. The chapter also provides information on vertical and horizontal casting systems, billet homogenization, and the cause of casting defects, including cracking and splitting, segregation, porosity, and grain growth.
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Conference papers on the topic "Extrusion defects"

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Joun, Man-Soo, Min-Cheol Kim, Duk-Jae Yoon, Ho-Joon Choi, and Yo-Hun Son. "Finite Element Analysis of Central Bursting Defects Occurring in Cold Forward Extrusion." In ASME 2011 International Manufacturing Science and Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/msec2011-50148.

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An improved approach to simulating the formation of central bursting defects is presented in this paper. The rigid-plastic finite element method and a modified McClintock damage model are employed. An improved node-splitting technique with degenerate element cleaning is proposed. The technique is applied to several cold forward extrusion processes to reveal the effects of reduction of area, die conical angle, and friction on the formation of central bursting defects. A comparison with experimental results and predictions found in the literature shows that the present analysis provides more realistic predictions of the shape of a central bursting defect (i.e., an obtuse V-shape, which is typical).
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Labergère, C., P. Lestriez, and K. Saanouni. "Numerical simulation of burst defects in cold extrusion process." In MATERIALS PROCESSING AND DESIGN; Modeling, Simulation and Applications; NUMIFORM '07; Proceedings of the 9th International Conference on Numerical Methods in Industrial Forming Processes. AIP, 2007. http://dx.doi.org/10.1063/1.2741004.

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An, Jinho, Kwang-Jin Moon, Soyoung Lee, Do-Sun Lee, Kiyoung Yun, Byung-Lyul Park, Ho-Jun Lee, et al. "Annealing process and structural considerations in controlling extrusion-type defects Cu TSV." In 2012 IEEE International Interconnect Technology Conference - IITC. IEEE, 2012. http://dx.doi.org/10.1109/iitc.2012.6251586.

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Ho, H. W., J. C. H. Phang, A. Altes, and L. J. Balk. "Characterization of Interconnect Defects Using Scanning Thermal Conductivity Microscopy." In ISTFA 2004. ASM International, 2004. http://dx.doi.org/10.31399/asm.cp.istfa2004p0363.

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Abstract In this paper, scanning thermal conductivity microscopy is used to characterize interconnect defects due to electromigration. Similar features are observed both in the temperature and thermal conductivity micrographs. The key advantage of the thermal conductivity mode is that specimen bias is not required. This is an important advantage for the characterization of defects in large scale integrated circuits. The thermal conductivity micrographs of extrusion, exposed and subsurface voids are presented and compared with the corresponding topography and temperature micrographs.
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Tsai, Pei Y., and William Bornstein. "Analysis of Ohmic Contact Metal Deposition Defect Using FIB/SEM for a GaAs MESFET Clock Buffer IC Device." In ISTFA 1999. ASM International, 1999. http://dx.doi.org/10.31399/asm.cp.istfa1999p0343.

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Abstract A major yield detractor in wafer final testing and outgoing production testing of a vendor supplied high frequency Gallium Arsenide (GaAs) clock buffer was encountered. The electrical failure modes are open, short, high Idd and gross functional fails. Physical analysis revealed the ohmic contact extrusion with a burst of Gallium from the substrate (GaAs) like a “mushroom” at the ohmic contact of the active layers of the MESFET and the MIM capacitors. The anomaly was not induced by ESD as it was proved by the ESD simulation test. The ESD test showed a much worse catastrophic damage than the extrusion anomaly. EDAX analysis identified high concentration of Ga in the extrusion. Focused Ion Beam (FIB) and Scanning Electron Microscopy (SEM) analysis of the extrusion showed large voids under the contact area at the defect location. Mis-alignment of interconnect metal to ohmic contact (Au-Ge-Ni) and pinholes in ohmic contact metal to active layers in substrate were found throughout the analysis. The pinholes causes the diffusion area to contact directly to the first level gold (Au) interconnect metal (M1). This results in Au-GaAs interdiffusion (mainly Ga) leaving a large void in the bulk substrate similar to kirkendahl voiding. Additional defects were found when the device was electrically biased. The problem was quickly fixed by slightly adjusting an angle in the sputtering process to provide a complete ohmic contact metal coverage on the diffusion contact and subsequently a yield improvement was resulted.
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Qamar, Sayyad Zahid. "Fracture Mechanics Based Life Prediction of Hollow Extrusion Dies." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-93109.

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Hot metal extrusion dies, especially for hollow profiles, are quite costly. Repair or replacement of dies and affiliated tooling adds to the cost, brings down productivity, and can contribute to product defects. Reasons for the high production and maintenance cost are stringent material requirements (high-strength and high-hardness tool steels), precision manufacturing methods (spark erosion, wire EDM, etc), and a series of specialized heat treatment and surface hardening operations. Consequently, a major goal for die designers and manufacturers is longer service life. An equally important objective is a reasonably accurate prediction of time-to-failure, to help devise an optimum replacement and inventory strategy, and for good performance evaluation. Majority of hot-work extrusion dies fail by fatigue fracture. Treating the die as a flat plate with edge crack, a fracture mechanics based fatigue life prediction model was developed by the authors in an earlier work. To improve the precision of die life prediction, a hollow (tube) extrusion die is modeled in the current work as a pressurized cylinder with internal crack. Based on this new strategy, a model is developed to forecast fracture failure of extrusion dies. Stochastic nature of various fatigue related die parameters is examined. Monte Carlo simulation is used for die life prediction under a given set of operating conditions and mechanical properties. Simulated fracture life values thus obtained are quite realistic in comparison with actual extrusion die life data from the industry.
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Hsiang, Su-Hai, and Yi-Wei Lin. "Study on the Mechanical Properties of AZ31 Magnesium Alloy Products Under Hot Extrusion Process." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95241.

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Magnesium alloy parts have the merits of low specific gravity, high specific strength, electromagnetic wave-proof shelter, and recyclability; therefore, it has been extensively applied to 3C and car industries. However, the processing and forming of magnesium is quite difficult to control due to magnesium’s hexagonal close-packed (HCP) structure, making the slipping face of itself less than the FCC material. Currently, common processing methods of magnesium alloys are die casting, semi-solid forming, and plastic forming. In the employment of a fixed-speed method for extrusion, the extruded sheet had serious defects in the forms of cracks on the surface. Hence, in this research, AZ31 magnesium alloy sheet metals were processed by hot extrusion using a variable speed method. The formability of AZ31 sheets under converging dies was investigated. Three converging dies with semi die angle of 20°, 30°, and 40° were used. Experiments were conducted and analyzed utilizing the Taguchi method. L9 orthogonal array was used to design the experiments under extrusion ratio of 35.9. Four important process parameters considered in this research are the heating temperature of the billet (320°C, 340°C and 360°C), the temperature of the container (300°C, 350°C and 400°C), the initial speed of extrusion (2mm/sec, 3mm/sec and 4mm/sec), and the lubricants (boron nitride, molybdenum disulphide and graphite) applied in the extrusion. The influences of these parameters to the extrusion load and the resulting mechanical properties were investigated. Moreover, the microstructure of the extruded sheets was observed to provide better insight of the formability. As a result, the optimal combinations of the process parameters were determined for the maximum tensile strength.
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Schroeffer, Andreas, Matthias Trescher, Konstantin Struebig, Yannik Krieger, and Tim C. Lueth. "A Rapid Manufacturing Process for Extrusion-Based 3D Printers." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10022.

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Abstract The generation of plastic parts in small volume batches has an enormous economic significance. Application fields for parts in small lot sizes are the fabrication of prototypes in the design process or individualized products. The goal thereby often is not only to produce show objects, but functional parts with specific materials, high dimensional accuracy and proper mechanical properties in a short amount of time. The conventional way to produce thermoplastic plastic parts is given by injection molding and extrusion. Characteristics for this technology are the resulting good and homogeneous mechanical component properties, but shape freedom is limited and the process is time consumptive because an individual tool is needed for each product. Depending on the design of the part the geometry of the tool can be complex and an iterative process is necessary to create a suitable mold. On the other hand, the technology of additive manufacturing is a growing market for the quick and cheap production of parts as prototypes, but still the range of materials is limited and anisotropic mechanical component properties are ongoing problems. The combination of both technologies is known as rapid tooling, where the mold is produced in an additive manufacturing process and then used in an injection molding or casting process. This approach combines the benefits of both technologies in term of time and cost efficiency and good component properties. Problems here are the combination of different materials for mold and component and the missing process knowledge and automatization. In this paper an extrusion-based additive manufacturing technology is used to combine additive manufacturing and injection infill generation for thermoplast in one process. The proposed working principle is to generate the outer contour of the part by filament extrusion as mold to ensure high accuracy and good surface quality and fill the mold using an extrusion process of polymer melt without filament generation. Accordingly, the mold becomes part of the component and the same material can be used for the mold and the infill. Since the viscosity of most thermoplastic polymer melts is too high to fill big structures and undercuts, an algorithm is proposed to generate a chamber structure inside the part. Consequently, the fabrication process consists of several iterative cycles of mold generation and injection processes. For this paper polyamide 6 is used to demonstrate the process. Experiments were performed to find the optimal chamber geometry and size to avoid holes and generate a high quality infill. Several component properties such as density, tensile strength and fabrication time are analyzed. In spite of still existing blowholes, a higher component density could be achieved with the proposed process compared to additive manufacturing. However, the tensile strength is still significantly lower. The failures appeared at the weld lines, where warm polymer melt was injected to already colder chambers below. Still manual processes are sources of possible defects as well. The integration of a RFID chip is shown as an additional feature of the process of easy integration of passive electronic elements.
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Funke, Lawrence, James P. Schmiedeler, and Kai Zhao. "Design of Planar Multi-Degree-of-Freedom Morphing Mechanisms." In ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-35265.

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This paper seeks to advance the design of planar shape-changing mechanisms used in a variety of applications, such as morphing extrusion dies and airfoils. The presence of defects is a limiting factor in finding suitable single-degree-of-freedom (DOF) mechanisms, particularly when the number of shapes to achieve is large and/or the changes among those shapes are significant. This paper presents a new method of designing multi-DOF mechanisms to aid in avoiding these defects. The primary method uses a building-block approach similar to the current one-DOF synthesis procedure and is compared to alternative strategies that seek to leverage the use of multiple single-DOF subchains. While more complex in terms of determining the actuation pattern, the primary method offers a larger design space in which to find solutions. In all cases a genetic algorithm is employed to search the design space. Two example problems involving four prescribed shapes demonstrate the benefits of using multi-DOF mechanisms in terms of shape matching and mechanical advantage.
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Sultana, Quazi Nahida, Saheem Absar, Stephanie Hulsey, Hans Schanz, and Mujibur Khan. "Synthesis and Processing of Solution Spun Cellulose Acetate Fibers Reinforced With Carbon Nanotubes." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50804.

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We report the fabrication of Cellulose Acetate (CA) based fibers reinforced with Multi-Walled Carbon Nanotubes (MWCNTs) using a solution spinning process. The motivation of this work is to produce high performance fibers based on sustainable natural materials as an alternative to synthetic fibers for structural applications. A 30 wt% solution of CA in a binary solvent system of N, N-dimethylacetamide (DMAc) and Acetone (3:7 v/v) was used for the solution spinning of CA fibers. Both neat and CNT-loaded CA fibers were produced. The CNT loading with respect to the polymer was at 0.5 wt%. For CA-MWCNT spinning solutions, the MWCNTs were initially dispersed in the solvent and then CA is added and mixed together. The mixing temperature kept 40–45°C. The viscosity of the CA solution was 8,000 cP. Addition of MWCNT increased the viscosity of the CA solution to 32,000 cP. A lab-scale solution spinning line consisting of a constant torque high temperature gear pump and heated extrusion channels was used to produce both neat and CA-MWCNT fibers. The solution was pumped through a spinneret at the end of the extrusion channel with an orifice as a viscous gel-like filament which was passed through a spool placed in a coagulation bath and then it formed as fiber. The fibers are collected to a takeup roll at a draw ratio of 8.0. Characterization studies of both neat and MWCNT loaded fibers were performed differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and scanning electron microscopy (SEM). DSC analysis of fibers showed reduction in crystallinity of CA upon inclusion of 0.5 wt% MWCNT. TGA analysis showed improvement of thermal stability in CA-MWCNT fibers compared to neat CA. Cross-sections of neat CA fibers showed smooth surfaces with no significant defects, while CA-MWCNT showed formation of micro-voids and irregular features. Longitudinal views of outer surface of both neat CA and CA-MWCNT fibers showed no indication of surface defects or protrusions.
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Reports on the topic "Extrusion defects"

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Suranuntchai, Surasak, and Prarop Kritboonyarit. Limit Diagrams for Selecting Process Parameters to Prevent Defects Formation during Forward Bar Extrusion Using FEM. Warrendale, PA: SAE International, October 2005. http://dx.doi.org/10.4271/2005-32-0043.

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