Journal articles: 'Extrusion defects'

1

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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11

McAllen, P., and P. Phelan. "A method for the prediction of ductile fracture by central bursts in axisymmetric extrusion." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 219, no. 3 (March 1, 2005): 237–50. http://dx.doi.org/10.1243/095440605x16820.

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A new approach for the prediction of central burst defects in extrusion and wire drawing is proposed. Central burst defects are troublesome in industry as it is impossible to detect these defects by simple visual examination alone. It is therefore important to identify the combination of process parameters that will reduce the probability of these defects occurring. The proposed approach is capable of accurately predicting when and where a central burst is likely to occur. The influence of die geometry on damage development and subsequent central burst formation is examined using the modelling capabilities of Abaqus finite element software. The ductile fracture criteria of Cockcroft and Latham, Oyane and Chaouadi were employed using a Fortran subroutine, and their ability to predict the onset and evolution of the central burst defect was examined. For relatively lower area reductions and die angles the considered criteria are capable of accurately predicting the morphology of the defect. Under these conditions, the proposed approach shows good agreement with experimental results, confirming its effectiveness and suitability for industrial application. The failure criteria are inadequate in predicting central burst defect formation during conditions of large reduction in area and large semi-die angles. Further development of ductile failure criteria is necessary to accurately simulate defect evolution for all die angles and area reductions.

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Phanitwong, Wiriyakorn, and Sutasn Thipprakmas. "Finite element analysis of piping defect formation in the sheet-extrusion process." International Journal of Modeling, Simulation, and Scientific Computing 06, no. 01 (March 2015): 1550010. http://dx.doi.org/10.1142/s1793962315500105.

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The pressing process, as compared to the machining process, makes good utilization of work piece material and shortens the production time, and as such it is increasingly used for production of complex shaped parts. A particular type of pressing is sheet-extrusion which controls the flow of material into special punch and die sets to produce an extruded shape. However, some particularly complex shaped parts cannot be made by sheet-extrusion due to the formation of piping defects. In this study, the finite element method (FEM) was used to investigate the formation of piping defects. In addition, the relationship between the characteristic dimensions of the extruded shape and the piping defect was also examined. Laboratory pressing experiments were performed to validate the accuracy of the FEM simulation results. Based on the stress distribution and velocity profiles within the extruded work piece, the relationship between the extruded shape and the piping defect was clearly identified. Furthermore, the FEM simulation results showed good agreement with the experimental results with regards to the dimensions of the extruded shape and the piping defect.

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Lin, Heng-Sheng, Chien-Yu Lee, and Wen-Shun Li. "Piercing and Surface-Crack Defects in Cold Combined Forward-Backward Extrusion." Applied Sciences 11, no. 9 (April 26, 2021): 3900. http://dx.doi.org/10.3390/app11093900.

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Metal flow tends to be complex and difficult to predict in the combined forward-backward extrusion (CFBE) process. Piercing and surface-crack defects are phenomenal in forming fasteners featuring a forward extruded pin and a backward extruded cup. In this work, a series of the CFBE tests with various combinations of the forward extrusion ratio (FER) and the backward extrusion ratio (BER) were conducted. A forming limit diagram, detailed with the piercing and surface-crack defects on the forward extruded pin or the backward extruded cup, was developed to provide a conception in choosing appropriate extrusion ratios in forming fasteners with such pin-and-cup features. With the aid of the forming load-stroke curves and the finite element analysis of fracture damage, the fracturing mechanism for the CFBE process was provided.

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14

Vergnes, B. "Extrusion Defects and Flow Instabilities of Molten Polymers." International Polymer Processing 30, no. 1 (March 2, 2015): 3–28. http://dx.doi.org/10.3139/217.3011.

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Qamar, Sayyad, Tasneem Pervez, and Josiah Chekotu. "Die Defects and Die Corrections in Metal Extrusion." Metals 8, no. 6 (May 24, 2018): 380. http://dx.doi.org/10.3390/met8060380.

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16

Avitzur, B., and J. C. Choi. "Analysis of Central Bursting Defects in Plane Strain Drawing and Extrusion." Journal of Engineering for Industry 108, no. 4 (November 1, 1986): 317–21. http://dx.doi.org/10.1115/1.3187082.

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Based on the upper-bound theorem in limit analysis, the central bursting defect in plane strain drawing and extrusion is analyzed by comparing the proportional flow with the central bursting flow for the metal with voids at the center. A criterion for the unique conditions that promote this defect has been derived. The metal with voids may flow in the identical manner to that of solid strip with no voids to form a sound flow, deterring central bursting. A solid strip, on the other hand, or a material with voids, may flow in a manner so as to produce central bursting defects. A major conclusion of the study is that, for a range of combinations of inclined angle of the die, reduction, and friction, central bursting is expected whether or not the material originally had any voids. On the other hand, central bursting can be prevented even if the original rod contains small-size voids.

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17

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." Materials Science Forum 551-552 (July 2007): 293–96. http://dx.doi.org/10.4028/www.scientific.net/msf.551-552.293.

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The aim of the study on the deformation defect is to prevent defects and to improve the quality and to control the deformation. It is important that the preventive measure could be established to advance the scientificity of the product and processing design. In this paper, the reasons of the outer defects such as cracks are analyzed based on the superplasticity of the copper alloy and the process of solid cages in the superplastic extrusion. The prediction and numerical simulation of these typical defects are also carried out using the Deform-3D software grounded on the model of the rigid-visco plastic FEM. The position, time of crack appearance and relation between the strain rate and the defects are also studied. The simulated results are in equivalent agreement with the experiment.

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18

Miao, Cong, and Hai Bo Yang. "Analysis on the Optimal Process of Aluminum Profile Extrusion with Two-Hole Dies." Advanced Materials Research 1120-1121 (July 2015): 1246–50. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.1246.

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In this paper, using orthogonal design method, considering the extrusion temperature, extrusion speed, extrusion billet, die structure, which will affect the uniformity of the metal flow[1]. Using the outlet velocity average standard deviation, the average pressure and the mean maximum equivalent stress as the criterion, select the optimal process scheme of two-hole dies aluminum profile extrusion. And the optimal scheme is validated by simulation and, the results show that the extrusion velocity is uniform, no forming defects, it can stably forming. At the same time, the experiment provides theoretical guidance for real extrusion production with multi-hole dies.

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Huang, Shu Hui, Zhi Hui Li, Bai Qing Xiong, Yon Gan Zhang, Xi Wu Li, Hong Wei Liu, Hong Wei Yan, and Li Zhen Yan. "Microstructure and Porous Defects of a Spray-Formed and Hot Worked 7000 Aluminum Alloy." Materials Science Forum 879 (November 2016): 1778–82. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1778.

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The evolution of microstructure and porous defects of a spray-formed 7000 Aluminum alloy is researched in this paper. The spray-formed alloy is treated by hot isostatic pressing (HIP), homogenization, hot extrusion, solution and aging treatment. Metallographic microscope, scanning electron microscope (SEM) and tensile test are used to research the microstructure and mechanical properties. The results show that, there are two kinds of porous defects in spray-formed alloy, which has gas and no gas. The porous defects of spray-formed ingot can be mostly eliminated by HIP and hot extrusion. After solution and aging treatment, the tensile strength and elongation reach 757MPa and 10.2%, respectively.

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Iino, Shoichiro, Kouji Taira, Miho Machigashira, and Shouichi Miyawaki. "Isolated Vertical Infrabony Defects Treated by Orthodontic Tooth Extrusion." Angle Orthodontist 78, no. 4 (July 2008): 728–36. http://dx.doi.org/10.2319/0003-3219(2008)078[0728:ividtb]2.0.co;2.

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21

Combeaud, Christelle, Yves Demay, and Bruno Vergnes. "Experimental study of the volume defects in polystyrene extrusion." Journal of Non-Newtonian Fluid Mechanics 121, no. 2-3 (August 2004): 175–85. http://dx.doi.org/10.1016/j.jnnfm.2004.06.007.

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22

Saw, Thuan Beng, Amin Doostmohammadi, Vincent Nier, Leyla Kocgozlu, Sumesh Thampi, Yusuke Toyama, Philippe Marcq, Chwee Teck Lim, Julia M. Yeomans, and Benoit Ladoux. "Topological defects in epithelia govern cell death and extrusion." Nature 544, no. 7649 (April 13, 2017): 212–16. http://dx.doi.org/10.1038/nature21718.

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23

Demay, Y., and J. F. Agassant. "The Polymer Film Casting Process – An Overview." International Polymer Processing 36, no. 3 (July 1, 2021): 264–75. http://dx.doi.org/10.1515/ipp-2020-4061.

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Abstract Cast film extrusion allows producing technical polymer films for packaging and coating applications. Different kinds of defects may be observed. For packaging applications, the challenge is to obtain very thin films in stable conditions at the highest throughput. For coating applications, the challenge is to master the film width reduction (called neck-in) and the induced non-uniform film thickness (called dog-bone defect). Well instrumented experiments point out the influence of the polymer and of the processing conditions on the occurrence of these defects. Numerical models of increasing complexity allow capturing the main experimental features and this makes possible to propose technological solutions to delay or even to suppress defects occurrence.

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Xu, Yong Tao, Tian Yang Guan, Zhi Feng Zhang, Yue Long Bai, and Wei Min Mao. "Semi-Solid Rheological Squeeze Casting Process of ZL114A Aluminum Alloy Thin-Wall Complex Casting." Materials Science Forum 993 (May 2020): 248–53. http://dx.doi.org/10.4028/www.scientific.net/msf.993.248.

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High-strength aluminum alloy with large-scale and thin-walled complex castings have broad application prospects in aerospace, weapons, electronics, defense and military industries. However, due to the uneven thickness of the plate, the casting defects are inevitable by the ordinary casting method, and it is impossible to accurately control the shape and performance of the casting in the casting process. Previous studies have found that the semi-solid rheological extrusion casting technology with short process and near-end type can help solve this technical problem. Therefore, this paper studies the semi-solid rheological extrusion casting process of thin-walled complex casting of ZL114A aluminum alloy. The combination of numerical simulation and experimental research is used to simulate and optimize the filling and solidification process of thin-walled specimens. Based on this, a semi-solid rheological extrusion casting test was conducted. The result showed that, (1) The optimized model can well reflect the filling and solidification process under different rheological extrusion casting parameters, and obtain defect-free castings through process optimization. (2) The thin-walled parts of the thin plate casting produced by semi-solid rheology extrusion have excellent mechanical property and ductility.

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Guo, Yong Qiang, Chun Guo Xu, Guang Sheng Ren, and Gui Hua Liu. "Optimization of Forming Technique during Necking Extrusion of Drill Pipe Joints." Advanced Materials Research 291-294 (July 2011): 569–72. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.569.

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By using finite element method, the causes of forming defects such as shortage of material and punching recess thickened during drill pipe joints forging were studied and some solutions were put forward. According to the numerical simulation results, one forming defect named shortage of material caused by the metal irregular flow at the bottom of necking die, which can be resolved by reducing the die forming-angle and increasing the width of the punch. On the condition with D0/d0≤2.6 (D0 refers to outer diameter, d0 refers to inner diameter), necking process can be completed with one-step backward extrusion. The thicker punching recess is formed by the accumulated metal which was scraped by the punch during necking extrusion. This kind of defect can not be eliminated, but can be minimized by improving friction conditions.

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Lv, Qing Qing, Li Quan Yang, Xiu Ting Lv, Lei Zhao, and Xi Kui Wang. "Numerical Simulation Optimization Research of Cold Extrusion Forming for Injection Head." Advanced Materials Research 706-708 (June 2013): 444–47. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.444.

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In order to obtain high-quality injection head, cold extrusion forming is adopted. Based on the study of forming technology for the injection head, reasonable process flow, cold extrusion pre-treatment process and boundary conditions are designed. Two finite element models in forward extrusion and backward extrusion forming ways are established. Taking DEFORM as the platform, the numerical simulation of forming process is carried out. Through simulation, the distribution of strain field, stress field and velocity field in the process of cold extrusion forming is preliminarily forecast, the merits and defects of two kinds of forming processes and the force state of mold are compared , the optimal forming scheme is determined.

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Zheng, Wei Gang, Cun Hong Yin, Yu Hong Yuan, Zhen Min Pan, and Chao Tang. "Study on Local Extrusions' Effects on Improvement of Die Casting Prismatic Parts' Forming Quality." Applied Mechanics and Materials 312 (February 2013): 475–79. http://dx.doi.org/10.4028/www.scientific.net/amm.312.475.

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This paper analyzes traditional die casting process to find out the reasons that cause shrinkage cavity and porosity defects in casting. An optimized process of die casting by using local extrusion is proposed. A device used in local extrusion which realizes forcing compensating contraction on key parts of crankcase is designed and the parameters of local extrusion process are discussed. Compared the mechanical properties and microstructure of local extrusion used in die casting production with traditional. It shows that local extrusion used in die casting production can not only achieve the aim eliminating shrinkage porosity and cavity of a casting but also can refine grain to improve the mechanical properties.

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Goldshtein, Alexander, Galina Vavilova, Alexander Rumkin, and Oldrich Starý. "Detection of Insulation Defects in Automated In-Process Testing of Electric Wire during its Extrusion." Materials Science Forum 942 (January 2019): 141–50. http://dx.doi.org/10.4028/www.scientific.net/msf.942.141.

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The paper describes the electro-capacitive method for monitoring wire capacitance, which is implemented using the CAP-10 device, employed for in-process testing of the single core electric wire capacitance. Focus is made on the operating principle of the CAP-10 device. The possibility of using the CAP-10 device for detecting local defects in wire insulation is proved. Insulation defects such as foreign inclusions in the form of copper shavings, air cavities inside insulation and those at the core–insulation boundary are modeled. The impact of the defect geometric parameters on the wire capacitance measured during in-process testing is investigated through numerical simulation. Mathematical simulation results are validated through the physical model using the CAP-10 device.

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Radovic, Ljubica M., Jelena Marinkovic, and Milorad Stanic. "Effects of initial microstructure on the earring of aluminium alloys cartridge case." Metallurgical and Materials Engineering 25, no. 1 (March 31, 2019): 11–22. http://dx.doi.org/10.30544/409.

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Defects obtained during impact extrusion of EN AW-5754 aluminium alloy during cartridge case production were investigated. In cartridge cases produced from the one metallurgical heat pronounced tendency to earing after impact extrusion observed/appeared. On the other hand the earing in cartridge cases from the other heat was not observed. Presence of earing is due to local difference in materials flow during extrusion. This behaviour is atriduted to dfference in second phase particle distribution in used preforms (slugs).

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Muehlhause, Jerome, Sven Gall, and Sören Müller. "Simulation of the Co-Extrusion of Hybrid Mg/Al Profiles." Key Engineering Materials 424 (December 2009): 113–19. http://dx.doi.org/10.4028/www.scientific.net/kem.424.113.

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Extrusion of composite materials can offer big advantages. In this work the manufacturing of a hybrid metal profile in a single production step was investigated. A porthole die was used, thus producing profiles with extrusion seams. Along the seams a material mix up was visible. The extrusion process was simulated with the Finite Element Method to investigate the material flow in die and welding chamber in order to understand the cause for the defects at the seams.

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Hu, Lian Xi, Yuan Yuan, and Shou Jing Luo. "Fabrication, Microstructure and Mechanical Properties of a SiCw/ZK51A Mg Composite by Semi-Solid Extrusion Directly Following Liquid Infiltration." Solid State Phenomena 116-117 (October 2006): 354–57. http://dx.doi.org/10.4028/www.scientific.net/ssp.116-117.354.

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A 20vol.%SiCw/ZK51A Mg-based composite was fabricated by the process of semi-solid extrusion directly following liquid infiltration. The microstructure and mechanical properties of the composite were investigated in comparison with its squeeze cast and hot extruded counterpart. The results showed that, by semi-solid extrusion, the SiC whiskers were well aligned and microstructure defects associated with the casting technology were eliminated. In addition, as compared with the conventional hot extrusion, the damage to the SiC whiskers during semi-solid extrusion was reduced significantly. Consequently, the composite fabricated by the semi-solid extrusion presented the best whisker reinforcing effect, with its elastic modulus, 0.2% offset yield strength, and ultimate tensile strength achieving 82.5GPa, 383.6MPa, and 431.8MPa respectively.

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Pieła, K., L. Błaz, and M. Jaskowski. "Effects of Extrusion Parameters by KoBo Method on the Mechanical Properties and Microstructure of Aluminum." Archives of Metallurgy and Materials 58, no. 3 (September 1, 2013): 683–89. http://dx.doi.org/10.2478/amm-2013-0055.

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Abstract Commercial purity aluminum was extruded by means of KoBo method at varied processing parameters. Received extrudates, with different mechanical and electrical properties and work hardening behavior, were obtained. It was found, that some conditions of KoBo extrusion process such as low initial billet temperature, low extrusion rate and low frequency of oscillating die lead to extremely high strength and high electrical resistivity of the material. The absence of work hardening (up to 40% strain) during subsequent groove rolling is also a specific feature of received materials. It was suggested that mentioned features are related to the development of overbalance concentration of point defects (clusters) generated during the extrusion process. During following cold rolling of the extrudate, mentioned defects annihilate at gliding dislocations and make the dislocation climbing and their rearrangement easier. Therefore, until the exhaustion of this mechanism, the hardening of material during cold rolling is very limited. Following increase of the material strengthening at higher rolling strains point to the return of the material to its typical behavior observed for cold deformed aluminum produced by conventional hot extrusion.

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Batool, Lubaba, Zukhruf Nawaz, Irsa Jahangir, Zeeshan Abbasi, and Anjum Tauqir. "Decipher Ultrasonic Signals from Defects in Thick Aluminum Extrusions to Identify Type and Origin of Defects." Key Engineering Materials 875 (February 2021): 248–55. http://dx.doi.org/10.4028/www.scientific.net/kem.875.248.

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Manufacturing of thick seamless pipes of age-hardenable aluminum alloys are a specialized technology since their application is limited to specific hi-tech areas. Quality criteria for their inspection are propriety items of the very few production facilities that develop these criteria in-house. Present study relates ultrasonic signals reflecting back from non-continuities in the thickness of seamless pipes with their microstructural features. Detailed study of defects leads to the source of their formation and will ultimately help to systematically control them. Signals from ultrasonic testing trace defects as UT waves reflect back from discontinuities in the material. Defective sections of seamless pipes were cut with precision to reveal the defects. The sectioned surfaces were subjected to metallographic preparation and revealed defects were studied using Optical and Field Emission Scanning Electron Microscopes (FESEM). Defects are grouped based on the shape of UT signals as well as the defect morphology as revealed by microscopic studies. Most of the observed cracks are found to grow in the direction of extrusion. Energy Dispersive Spectroscopy (EDS) analysis was conducted to determine the composition of inclusions in the vicinity of the defects. Data from elemental analysis is used to identify the potential sources. The study recommends measures to control the defects and improve the yield.

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Qamar, S. Z., A. F. M. Arif, and A. K. Sheikh. "Analysis of Product Defects in a Typical Aluminum Extrusion Facility." Materials and Manufacturing Processes 19, no. 3 (December 28, 2004): 391–405. http://dx.doi.org/10.1081/amp-120038650.

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Lin, Heng-Sheng, Chien-Yu Lee, Wen-Shun Li, and Cheng-Tsung Wu. "Piercing and surface-crack defects in combination extrusion of fasteners." MATEC Web of Conferences 123 (2017): 00018. http://dx.doi.org/10.1051/matecconf/201712300018.

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Lee, Youngtak, and Doug Link. "Practical Application and Analysis of Lead-Free Solder on Chip-On-Flip-Chip SiP for Hearing Aids." International Symposium on Microelectronics 2017, no. 1 (October 1, 2017): 000201–7. http://dx.doi.org/10.4071/isom-2017-wa24_104.

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Abstract Due to rapid growth of the microelectronics industry, packaged devices with small form factors, low costs, high power performance, and increased efficiency have become of high demand in the market. To realize the current market development trend, flip chip interconnection and System-in-Package (SiP) are some of the promising packaging solutions developed. However, a surprising amount of surface mount technology (SMT) defects are associated with the use of lead-free solder paste and methods by which the paste is applied. Two such defects are solder extrusion and tombstoning. Considerable amount of defects associated with solder overflow are found on chip-on-flip-chip (COFC) SiP in hearing aids. Through the use of design of experiments (DOE), lead-free solder defect causes on hearing aids application can be better understood and subsequently reduced or eliminated. This paper will examine the failure modes of solder extrusion and tombstoning that occurred when two different types of lead-free solders, Sn-Ag-Cu (SAC) and BiAgX were used within a SiP for attachment of surface mount devices (SMD) chip components for hearing aid applications. The practical application and analysis of lead-free solder for hearing aids will include the comprehensive failure analysis of the SMD components and compare the modeling and analysis of the two different solder types through the DOE process.

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Suriyapha, Chatkaew, Bopit Bubphachot, and Sampan Rittidech. "Study of Microstructure and Mechanical Properties Effects on Workpiece Quality in Sheet Metal Extrusion Process." Scientific World Journal 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/848126.

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Sheet metal extrusion is a metal forming process in which the movement of a punch penetrates a sheet metal surface and it flows through a die orifice; the extruded parts can be deflected to have an extrusion cavity and protrusion on the opposite side. Therefore, this process results in a narrow region of highly localized plastic deformation due to the formation and microstructure effect on the work piece. This research investigated the characteristics of the material-flow behavior during the formation and its effect on the microstructure of the extruded sheet metal using the finite element method (FEM). The actual parts and FEM simulation model were developed using a blank material made from AISI-1045 steel with a thickness of 5 mm; the material’s behavior was determined subject to the punch penetration depths of 20%, 40%, 60%, and 80% of the sheet thickness. The results indicated the formation and microstructure effects on the sheet metal extrusion parts and defects. Namely, when increasing penetration, narrowing the die orifice the material flows through, the material was formed by extruding, and defects were visibility, and the microstructure of the material’s grains’ size was flat and very fine. Extrusion defects were not found in the control material flow. The region of highly localized plastic deformation affected the material gain and mechanical properties. The FEM simulation results agreed with the experimental results. Moreover, FEM could be investigated as a tool to decrease the cost and time in trial and error procedures.

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Kinne, Raimund W., Francesca Gunnella, Elke Kunisch, Sascha Heinemann, Berthold Nies, Stefan Maenz, Victoria Horbert, et al. "Performance of Calcium Phosphate Cements in the Augmentation of Sheep Vertebrae—An Ex Vivo Study." Materials 14, no. 14 (July 12, 2021): 3873. http://dx.doi.org/10.3390/ma14143873.

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Oil-based calcium phosphate cement (Paste-CPC) shows not only prolonged shelf life and injection times, but also improved cohesion and reproducibility during application, while retaining the advantages of fast setting, mechanical strength, and biocompatibility. In addition, poly(L-lactide-co-glycolide) (PLGA) fiber reinforcement may decrease the risk for local extrusion. Bone defects (diameter 5 mm; depth 15 mm) generated ex vivo in lumbar (L) spines of female Merino sheep (2–4 years) were augmented using: (i) water-based CPC with 10% PLGA fiber reinforcement (L3); (ii) Paste-CPC (L4); or (iii) clinically established polymethylmethacrylate (PMMA) bone cement (L5). Untouched (L1) and empty vertebrae (L2) served as controls. Cement performance was analyzed using micro-computed tomography, histology, and biomechanical testing. Extrusion was comparable for Paste-CPC(-PLGA) and PMMA, but significantly lower for CPC + PLGA. Compressive strength and Young’s modulus were similar for Paste-CPC and PMMA, but significantly higher compared to those for empty defects and/or CPC + PLGA. Expectedly, all experimental groups showed significantly or numerically lower compressive strength and Young’s modulus than those of untouched controls. Ready-to-use Paste-CPC demonstrates a performance similar to that of PMMA, but improved biomechanics compared to those of water-based CPC + PLGA, expanding the therapeutic arsenal for bone defects. O, significantly lower extrusion of CPC + PLGA fibers into adjacent lumbar spongiosa may help to reduce the risk of local extrusion in spinal surgery.

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Lee, Youngtak, and Doug Link. "Comparative Modeling and Analysis of Lead-Free Solder Extrusion for the Design of Reliability." International Symposium on Microelectronics 2016, no. 1 (October 1, 2016): 000111–16. http://dx.doi.org/10.4071/isom-2016-tp53.

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Abstract Due to rapid growth of the microelectronics industry, packaged devices with small form factors, low costs, high power performance, and increased efficiency have become of high demand in the market. To realize the current market development trend, flip chip interconnection and System-in-Package (SiP) are some of the promising packaging solutions developed. However, a surprising amount of surface mount technology (SMT) defects are associated with the use of lead-free solder paste and methods by which the paste is applied. Two such defects are solder extrusion and tombstoning. Through the use of design of experiments (DOE), lead-free solder defect causes can be better understood and subsequently reduced or eliminated. This paper will examine the failure modes of solder extrusion and tombstoning that occurred when two different types of lead-free solders, Sn-Ag-Cu (SAC) and BiAgX were used within a SiP for attachment of surface mount devices (SMD) chip components. The systematic investigation will include the comprehensive failure analysis of the SMD components and compare the modeling and analysis of the two different solder types utilizing the design of experiments methods.

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Gelaw, Mengistu, Perumalla Janaki Ramulu, Dagmawi Hailu, and Tariku Desta. "Manufacturing and mechanical characterization of square bar made of aluminium scraps through friction stir back extrusion process." Journal of Engineering, Design and Technology 16, no. 4 (August 6, 2018): 596–615. http://dx.doi.org/10.1108/jedt-02-2018-0030.

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Purpose The purpose of this paper is to manufacture an aluminium square cross-sectional bar by using conventional lathe machine from aluminium scraps through friction stir back extrusion (FSBE) process and study the viability of the process to produce the square bar. Design/methodology/approach The important tasks involved in this work are as follows: designing and manufacturing the chamber and plunger components used for experimental work, experimentally studying the thermo-mechanical progression of FSBE process on adapted conventional lathe machine and analyzing the relation between controlled parameter (like rotational speed and consolidation time) and response parameter (like extrusion time, extrusion rate, grain structure and hardness). Findings Preliminary results show that increasing or decreasing rotational speeds results in defects. Cold crack and twisting defect were shown on square bar fabricated using low rotational speed, and hot crack defects were observed on surface of the bars produced by higher rotational speed. The manufactured square bars were tested using optical microscope and Vickers hardness tester. Microstructural studies reveal that initial grains of aluminium wire undergo significant refinement and result in equiaxed and recrystallized grains in the square bar fabricated through FSBE method. The hardness tests show almost even distribution of hardness in the specimen, but hardness was lower than parent aluminium; in comparison, uneven distribution of hardness was seen in parent aluminium. Originality/value FSBE process is the new method to produce the bars and rods with better mechanical properties. The ambition of this work is to convert the existing scrap materials to useful products. Based on the literature review, the work has planned to perform extrusion process with the minimum effort and limited sources. In this manner, the work is highly original and under scientific mandate.

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Guo, Qing Miao, Zhen Lei Tang, Guo Liang Xie, Jie Hu, and De Fu Li. "The Extrusion Cracks of Inconel 625 Superalloy Tubes Caused by the Primary MC Carbides." Materials Science Forum 817 (April 2015): 550–55. http://dx.doi.org/10.4028/www.scientific.net/msf.817.550.

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Inconel 625 superalloy tubes were hot extruded using a horizontal extruder. Optical microscope, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) technique were employed to investigate the extrusion defects mainly caused by the primary MC carbides. The results showed that a lot of surface cracks, internal cracks, grooves and shrinkage cavity defects existed in the outer surface and internal of the Inconel 625 superalloy tube after hot extrusion. However, the inner surface of the tube was smooth and no cracks were observed. In addition to the external factors during hot extrusion, the cracks are mainly caused by the primary MC carbides or large dimension of C particles formed due to a relatively short smelting time and large dimension of C particles during smelting with the decreasing plasticity of the grain boundary. This kind of cracks can be avoided through improving the uniformity of the chemical composition by reducing the size of C particles and extending the diffusion time during the smelting of Inconel 625 superalloy.

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Katschnig, Matthias, Juergen Wallner, Thomas Janics, Christoph Burgstaller, Wolfgang Zemann, and Clemens Holzer. "Biofunctional Glycol-Modified Polyethylene Terephthalate and Thermoplastic Polyurethane Implants by Extrusion-Based Additive Manufacturing for Medical 3D Maxillofacial Defect Reconstruction." Polymers 12, no. 8 (August 5, 2020): 1751. http://dx.doi.org/10.3390/polym12081751.

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This work addresses the topic of extrusion-based additive manufacturing (filament-based material extrusion) of patient-specific biofunctional maxillofacial implants. The technical approach was chosen to overcome the shortcomings of medically established fabrication processes such as a limited availability of materials or long manufacturing times. The goal of the work was a successful fabrication of basic implants for defect reconstruction. The underlying vision is the implants’ clinic-internal and operation-accompanying application. Following a literature search, a material selection was conducted. Digitally prepared three-dimensional (3D) models dealing with two representative mandible bone defects were printed based on the material selection. An ex-vivo model of the implant environment evaluated dimensional and fitting traits of the implants. Glycol-modified PET (PETG) and thermoplastic polyurethane (TPU) were finally selected. These plastics had high cell acceptance, good mechanical properties, and optimal printability. The subsequent fabrication process yielded two different implant strategies: the standard implant made of PETG with a build-up rate of approximately 10 g/h, and the biofunctional performance implant with a TPU shell and a PETG core with a build-up rate of approximately 4 g/h. The standard implant is meant to be intraoperatively applied, as the print time is below three hours even for larger skull defects. Standard implants proved to be well fitting, mechanically stable and cleanly printed. In addition, the hybrid implant showed particularly cell-friendly behavior due to the chemical constitution of the TPU shell and great impact stability because of the crack-absorbing TPU/PETG combination. This biofunctional constellation could be used in specific reconstructive patient cases and is suitable for pre-operative manufacturing based on radiological image scans of the defect. In summary, filament-based material extrusion has been identified as a suitable manufacturing method for personalized implants in the maxillofacial area. A further clinical and mechanical study is recommended.

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Ai, Xianlong, Dan Wang, Junzheng Zhang, and Jie Shen. "Hippo signaling promotes Ets21c-dependent apical cell extrusion in the Drosophila wing disc." Development 147, no. 22 (October 7, 2020): dev190124. http://dx.doi.org/10.1242/dev.190124.

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ABSTRACTCell extrusion is a crucial regulator of epithelial tissue development and homeostasis. Epithelial cells undergoing apoptosis, bearing pathological mutations or possessing developmental defects are actively extruded toward elimination. However, the molecular mechanisms of Drosophila epithelial cell extrusion are not fully understood. Here, we report that activation of the conserved Hippo (Hpo) signaling pathway induces both apical and basal cell extrusion in the Drosophila wing disc epithelia. We show that canonical Yorkie targets Diap1, Myc and Cyclin E are not required for either apical or basal cell extrusion induced by activation of this pathway. Another target gene, bantam, is only involved in basal cell extrusion, suggesting novel Hpo-regulated apical cell extrusion mechanisms. Using RNA-seq analysis, we found that JNK signaling is activated in the extruding cells. We provide genetic evidence that JNK signaling activation is both sufficient and necessary for Hpo-regulated cell extrusion. Furthermore, we demonstrate that the ETS-domain transcription factor Ets21c, an ortholog of proto-oncogenes FLI1 and ERG, acts downstream of JNK signaling to mediate apical cell extrusion. Our findings reveal a novel molecular link between Hpo signaling and cell extrusion.

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Zhang, Chi, Xin Shang, and Rong Xiang. "Study on Cold Extrusion Process and Die for Vehicle Sleeve Gear with Spline." Advanced Materials Research 189-193 (February 2011): 2832–37. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.2832.

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This paper mainly looks at the research on cold extrusion process and die of vehicle gear sleeve with spline, optimized the cold extrusion process of the part using FEM analysis, which gives us a theoretical basis for further exploration on the cold extrusion, and selecting optimum process parameters. The optimized results were verified by experiments and mass production. It analyzes the effect of the punch shape of gear container to metal flowing. The plastic flow could be controlled by the selection of the punch shape of gear container which reduced the resistance to deformation, and the gear profile was full without folding defects.

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Qi, Le Hua, Li Jun Han, Ji Ming Zhou, Hai Ming Meng, Xin Yu, and Wen Jing Ma. "Experimental Study on C_F/Al Composite Plate with Complex Curved Surface Fabricated by Liquid-Solid Infiltration Extrusion." Solid State Phenomena 285 (January 2019): 197–202. http://dx.doi.org/10.4028/www.scientific.net/ssp.285.197.

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In this paper, continuous carbon fiber reinforced aluminum matrix (Cf/Al) composite plate with complex curved surface is fabricated by liquid-solid infiltration extrusion. The influence of fabrication parameters, such as the melting temperature, extrusion temperature and extrusion pressure on the Cf/Al composite plate is studied. The experimental results show that the liquid-solid infiltration extrusion process can be used to fabricate the Cf/Al composite with curved surface. The Cf/Al composite exhibits good infiltration and well-formed quality when the extrusion pressure is 50MPa, the extrusion temperature is 670°C and the melting temperature is 690°C. According to the microstructure observation, the carbon fiber uniformly distributes in the aluminum alloy matrix without damage and obvious defects. The density of the composite is decreased by 17.9%, from 2.71g/cm3 to 2.29g/cm3, which is lower than that of the matrix alloy, and the ultimate tensile strength is increased by 120% compared with the matrix alloy, from 127MPa to 279MPa.

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Lin, F. C., and Shen Yung Lin. "Predictions of the Minimum Amounts of Preforming in the Radial Extrusion of Tubular Components." Materials Science Forum 505-507 (January 2006): 769–74. http://dx.doi.org/10.4028/www.scientific.net/msf.505-507.769.

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Both the minimum relative depth of die cavity and the minimum amount required in preforming are determined to produce a defect-free product of tubular component in the preforming technique of radial extrusion in this study. This scheme is based on the least amount of material dissipation in radial extrusion of tubular component. A finite element based code is utilized to investigate the effects of various relative depths of die cavity, different percentage of preforming and relative height reduction on the material flow characteristics resulting in the movements of the defects locations. The abductive network is also applied to synthesize the data sets obtained from the numerical simulations. Consequently, a prediction model is established for organizing the minimum relative depth of die cavity and the related minimum amount required in preforming of the tubular component for different end strokes of deformation.

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Li, Feng, Hongbin Wu, and Minghan Qin. "Effects of processing parameters on the extrusion by continuous variable cross-section direct extrusion with 7A09 aluminium alloy." Modern Physics Letters B 30, no. 06 (March 7, 2016): 1650053. http://dx.doi.org/10.1142/s0217984916500536.

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In order to study the effects of processing parameters on the continuous variable cross-section direct extrusion (CVCDE), taking 7A09 aluminium alloy for example, the extrusion speed and forming temperature and the friction factor as key processing parameters are applied to research by finite element (FE) simulation. The research result showed that the extrusion speed had a significant influence on the maximum temperature of the billet, at the same time, both decreasing the friction factor and increasing forming temperature within a certain range were beneficial to reduce extrusion load. Both forming temperature and the extrusion speed were inversely linked to extrusion load, but the friction factor was directly proportional to extrusion load. Forming temperature had a far more important influence on extrusion load by comparison: when forming temperature increased from 380[Formula: see text] to 430[Formula: see text]C, the peak value of extrusion load decreased by 25.6% and the flow uniformity of extruded product got improved. The process window based on both the press limit and surface defects limit was established and the most reasonable forming temperature was 405[Formula: see text]C under this process condition, which provided theoretical basis for formulation process of 7A09 aluminium alloy on the CVCDE extrusion.

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Furui, Mitsuaki, Shouyou Sakashita, Kazuya Shimojima, Tetsuo Aida, Kiyoshi Terayama, Yusuke Ishisaka, Masayuki Yamamoto, and Masayuki Ohta. "Room Temperature Screw Form Rolling of AZ91D Magnesium Alloy through Processing by Extrusion-Torsion Simultaneous Working." Materials Science Forum 783-786 (May 2014): 375–79. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.375.

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Extrusion-torsion simultaneous processing is a very attractive technique for fabricating a rod-shape material with fine grain and random texture. We have proposed a new screw form rolling process combined with preliminary extrusion-torsion simultaneous working. Microstructure evolution and mechanical property change of AZ91D magnesium alloy during extrusion-torsion simultaneous processing was examined through microstructure observation, X-ray diffraction analysis and micro-Vickers hardness measurement. By the addition of torsion, the crystal orientation of AZ91D magnesium alloy workpiece was drastically changed from basal crystalline orientation to the random orientation. Crystal grain occurred through the dynamic recrystallization and tended to coarsen with an increase of extrusion-torsion temperature. Grain refinement under 2 um was achieved at the lowest extrusion-torsion temperature of 523 K. M8 gauge AZ91D magnesium alloy screw was successfully formed at room temperature using the extrusion-twisted workpiece preliminary solution treating at 678 K for 345.6 ks. It was found that the extrusion-torsion temperature of 678 K must be selected to fabricate the good screw without any defects.

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Bergmann, Christian J. D., Jim C. E. Odekerken, Tim J. M. Welting, Franz Jungwirth, Declan Devine, Ludovic Bouré, Stephan Zeiter, et al. "Calcium Phosphate Based Three-Dimensional Cold Plotted Bone Scaffolds for Critical Size Bone Defects." BioMed Research International 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/852610.

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Bone substitutes, like calcium phosphate, are implemented more frequently in orthopaedic surgery to reconstruct critical size defects, since autograft often results in donor site morbidity and allograft can transmit diseases. A novel bone cement, based onβ-tricalcium phosphate, polyethylene glycol, and trisodium citrate, was developed to allow the rapid manufacturing of scaffolds, by extrusion freeform fabrication, at room temperature. The cement composition exhibits good resorption properties and serves as a basis for customised (e.g., drug or growth factor loaded) scaffolds for critical size bone defects.In vitrotoxicity tests confirmed proliferation and differentiation of ATDC5 cells in scaffold-conditioned culture medium. Implantation of scaffolds in the iliac wing of sheep showed bone remodelling throughout the defects, outperforming the empty defects on both mineral volume and density present in the defect after 12 weeks. Both scaffolds outperformed the autograft filled defects on mineral density, while the mineral volume present in the scaffold treated defects was at least equal to the mineral volume present in the autograft treated defects. We conclude that the formulated bone cement composition is suitable for scaffold production at room temperature and that the established scaffold material can serve as a basis for future bone substitutes to enhancede novobone formation in critical size defects.

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Kwapisz, Marcin. "Analysis of the Shape of Stamp on the Distribution of Deformation in the Process of Alternate Pressing and Multiaxial Compression." Solid State Phenomena 220-221 (January 2015): 963–68. http://dx.doi.org/10.4028/www.scientific.net/ssp.220-221.963.

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The paper presents the results of numerical simulations of the alternate indirect extrusion and multiaxial compression process, performed using commercial software designed for the thermomechanical analysis of plastic working processes, Forge 2009. The paper presents selected results on the distribution of deformation in the process of alternating extrusion and multiaxial compression. Examples of modifications to the shape of the die and punch, and their effect on the kinetics of the material flow as well as the likelihood of defects of materials are provided. The results confirm that suitable modifying the shape of the die and punch enables to obtain a material with no internal defects. Iterative process, alternating squeezing and multiaxial compressive strain allows the accumulation of which results in fragmentation of the microstructure.

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Journal articles on the topic 'Extrusion defects'

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