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Ziolkowski, Joseph Edmund. "Modeling of an aerospace sand casting process." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-1223102-102625.
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Hock, Kuah Teng. "Numerical simulation of sand casting process." Ohio : Ohio University, 1987. http://www.ohiolink.edu/etd/view.cgi?ohiou1183046313.
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Saleem, Muhammad Qaiser. "Helium Assisted Sand Casting of Aluminum Alloys." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-dissertations/204.
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Sand casting is the most widely used casting process for both ferrous and non-ferrous alloys; however, the process is marred by large grain size structures and long solidification times. The coarser microstructure has a negative effect on the mechanical properties of the cast components and the long processing time affects the overall productivity of the process. The research reported herein addresses these problems for aluminum sand castings by enhancing the rate of heat extraction from the casting by replacing air, which is typically present in the pores of the sand mold and has a relatively low thermal conductivity by helium which has a thermal conductivity that is at least five times that of air in the temperature range of interest. The effect of (1) the flow rate of helium, (2) the way in which it is introduced into the mold, and (3) the mold design on (a) the average grain size, (b) the secondary dendrite arm spacing, and (c) the room temperature tensile properties of castings is investigated and compared to their counterparts produced in a typical sand casting process. In addition, a cost analysis of the helium-assisted sand casting process is performed and an optimum set of parameters are identified. It is found that when the helium-assisted sand casting process is performed with close to the optimum parameters it produces castings that exhibit a 22 percent increase in ultimate tensile strength and a 34 percent increase in yield strength with no significant loss of ductility, no degradation in the quality of the as-cast surfaces, and no significant increase in the overall cost.
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Spangler, Kimberly Hawkins. "Sand casting benchmarking questionnaire development, analysis, and participant evaluation /." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1532.
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Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains viii, 167 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 90-93).
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Heydari, Farhad. "Mechanisms of sand flow and compaction in core-blowing." Thesis, University of Warwick, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357857.
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Gourisankar, Vellapillil. "Computer modeling of parting plane problem." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/16813.
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Capps, Johnathon. "Advancements in vacuum process molding and casting." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Summer/master's/CAPPS_JOHNATHON_6.pdf.
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Tjoa, Robertus Tjin Hok Carleton University Dissertation Engineering Mechanical. "Assessment of the accuracy of a computational casting model." Ottawa, 1992.
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Spataro, Mark Paul. "Comparison of mechanical performance between magnesium alloy sand castings and high pressure die castings /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18378.pdf.
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Kambakas, Kyriakos. "Development of white cast iron matrix composites by sedimentation sand casting." Thesis, University of Surrey, 2006. http://epubs.surrey.ac.uk/843688/.
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In the work that is described in this thesis we studied a new cast iron based composite material that was produced by a double casting technique using sedimentation sand casting. The material is based on the high Cr white cast irons (WCI) 15, 20 % Cr-Mo- LC and 25 % Cr matrixes, according to ASTM A532-75a and was designed to exceed the wear life of wear resistant materials that are used in cement, mining, coal extraction and chemical and process industries currently. The working region of the material extends to a depth of 5-8 mm below the surface and is an in situ and ex situ particle reinforced composite. WC particles of different sizes (1-3 and 3-5 mm) were selected as the ex situ reinforcements. Thus, the composite consisted of a WCI matrix, which was reinforced with WC and other transition metal carbide particles. A sand casting method was developed during which the WC particles were directed to a specific location in the ingot and were distributed uniformly in the near surface area of the composite (the working region of the material) during casting/solidification of the ingot. This ensured chemical bonding between the high Cr WCI and the particle reinforced composite (the working region) at a well defined interface parallel to the working surface. Solidification of the melt started from the WC particles around which three reaction zones were formed. Owing to partial dissolution of the WC particles and the resulting interdiffusion of elements such as W, Co, Fe, C and Cr, carbides containing Fe, Cr, W and Co were formed in the reaction zones. It is shown that current models for the interaction between a reinforcing particle and an advancing S/L interface in liquid route MMCs cannot describe the present case successfully because the solidification of the melt starts around the WC particles after the latter have settled in the near surface region of the casting. Two new approaches have been studied; in the first the WC particles travel through the iron melt and settle at the bottom of the mould and in the second WC particles settled at the bottom of the mould experience the forces of the liquid flow. The solidification paths of the three WCI matrixes and MMCs have been simulated with the Scheil-Gulliver model using the Thermo-Calc software for different iron based alloy systems, by changing the W, Cr and C concentrations. In the WCI, carbides solidify after the austenite. The increase in Cr from 14 to 25 wt. %, for fixed C (at 2, 2.5 or 3 wt. %), causes the stabilization of phases according to cementite M7C3 FCC (stable). Only for Cr up to 30 wt. % and C up to 2.5 wt. % the cementite is replaced by the BCC phase. The increase in C content from 2 to 3 wt. % for fixed Cr (at 14, 20 or 25 wt. %) has the same effect. In the MMC, the increase in W from 15 to 25 wt. % causes the stabilization of M6C. As the C increases from 2.5 to 6 wt. %, first the M7C3 is stabilised and for C > 4 wt. % the MC phase is favoured. The increase in Cr leads in the formation of the M23C6 while simultaneous increase in Cr and C promotes the M7C3 phase and restrains the formation of the M6C that resulted from the increase of W. Finally the simultaneous increase of C, W and Cr stabilize the MC phase for > 4 wt. % C. The wear of the new materials was evaluated both in an industrial scale and in the laboratory (pin-on-disc). Segments of an industrial pulverising ash mill used in the cement industry were manufactured using the casting method and materials developed in this thesis. The results showed an improvement in the wear life of the component of several times compared to the standard high Cr WCI material used by the same industry to date.
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Soe, Shwe Pyi. "An investigation into sand tooling methods for the production of injection moulded prototype parts." Thesis, University of Sunderland, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323121.
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Nyembwe, Kasongo Didier. "Tool manufacturing by metal casting in sand moulds produced by additive manufacturing processes." Thesis, Bloemfontein : Central University of Technology, Free State, 2012. http://hdl.handle.net/11462/162.
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Thesis (D. Tech. ( Mechanical Engineering )) - Central University of technology, Free State, 2012In this study an alternative indirect Rapid Tooling process is proposed. It essentially consists of producing sand moulds by Additive Manufacturing (AM) processes followed by casting of tools in the moulds. Various features of this tool making method have been investigated. A process chain for the proposed tool manufacturing method was conceptually developed. This process chain referred to as Rapid Casting for Tooling (RCT) is made up of five steps including Computer Aided Design (CAD) modeling, casting simulation, AM of moulds, metal casting and finishing operations. A validation stage is also provided to determine the suitability of the tool geometry and material for RCT. The theoretical assessment of the RCT process chain indicated that it has potential benefits such as short manufacturing time, low manufacturing cost and good quality of tools in terms of surface finish and dimensional accuracy. Focusing on the step of AM of the sand moulds, the selection of available AM processes between the Laser Sintering (LS) using an EOSINT S 700 machine and Three Dimensional Printing using a Z-Corporation Spectrum 550 printer was addressed by means of the Analytic Hierarchy Process (AHP). The criteria considered at this stage were manufacturing time, manufacturing cost, surface finish and dimensional accuracy. LS was found to be the most suitable for RCT compared to Three Dimensional Printing. The overall preferences for these two alternatives were respectively calculated at 73% and 27%. LS was then used as the default AM process of sand moulds in the present research work. A practical implementation of RCT to the manufacturing of foundry tooling used a case study provided by a local foundry. It consisted of the production of a sand casting pattern in cast iron for a high pressure moulding machine. The investigation confirmed the feasibility of RCT for producing foundry tools. In addition it demonstrated the crucial role of casting simulation in the prevention of casting defects and the prediction of tool properties. The challenges of RCT were found to be exogenous mainly related to workmanship. An assessment of RCT manufacturing time and cost was conducted using the case study above mentioned as well as an additional one dealing with the manufacturing of an aluminium die for the production of lost wax patterns. Durations and prices of RCT steps were carefully recorded and aggregated. The results indicated that the AM of moulds was the rate determining and cost driving step of RCT if procurement of technology was considered to be a sunk cost. Overall RCT was found to be faster but more expensive than machining and investment casting. Modern surface analyses and scanning techniques were used to assess the quality of RCT tools in terms of surface finish and dimensional accuracy. The best surface finish obtained for the cast dies had Ra and Rz respectively equal to 3.23 μm and 11.38 μm. In terms of dimensional accuracy, 82% of cast die points coincided with die Computer Aided Design (CAD) data which is within the typical tolerances of sand cast products. The investigation also showed that mould coating contributed slightly to the improvement of the cast tool surface finish. Finally this study also found that the additive manufacturing of the sand mould was the chief factor responsible for the loss of dimensional accuracy. Because of the above, it was concluded that light machining will always be required to improve the surface finish and the dimensional accuracy of cast tools. Durability was the last characteristic of RCT tools to be assessed. This property was empirically inferred from the mechanical properties and metallographic analysis of castings. Merit of durability figures of 0.048 to 0.152 were obtained for the cast tools. It was found that tools obtained from Direct Croning (DC) moulds have merit of durability figures three times higher than the tools produced from Z-Cast moulds thus a better resistance to abrasion wear of the former tools compared to the latter.
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Demirel, Onur. "Development Of Automobile Chassis Parts Via Aluminum Extrusion And Sand Casting Technology." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614965/index.pdf.
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Due to the environmental issues related with fuel consumption and additionally passenger safety, aluminum space frame chassis is promising a big opportunity to design a lightweight structure with a high stiffness. Despite the lower stiffness and strength of aluminum in comparison to the conventional steel chassis, it can be compensated with changing thickness and design of structure by space frame geometry In this study, instead of using steel for automobile chassis, main goal is producing a space frame structure with using aluminum in an extrusion and sand casting processes and improve the stiffness. Chassis is designed according to calculations for moment of inertia, torsional and bending stiffness and in sufficient structural stiffness which can compete with steel chassis. Static finite element analysis was carried out to understand the chassis bending, torsional stiffness and fatigue behaviors. For frontal collisions, dynamic finite element analysis was also done to determine increases in the energy absorbance, specific energy absorbance and peak force for passenger safety. Aluminum profiles were produced by hot extrusion and joined with sand casting parts by TIG welding to manufacture a space frame structure. For main chassis profile, 6063 series of aluminum alloy was selected due to availability for extrusion process, weldability and having sufficient tensile strength and percent elongation and treatment response. Three point bending test was carried out to determine flexural strength. Moment of inertia calculations were done. Some parts such as side frame and shock absorber tower were produced by sand casting method. A similar composition to Silafont &ndash36 aluminum alloy was selected because of its high fluidity and good mechanical properties
despite it is a die cast alloy. Tensile, hardness and Charpy impact test were conducted to determine the mechanical characteristics of Silafont - 36 sand cast alloy. In addition to microstructure features and thermal analysis were also carried out to achieve sufficient alloy properties. Heat affected z one was investigated by hardness and tensile test to determine the mechanical properties change after welding process. In this space frame development study, A, B and C pillar parts were produced by Al &ndash
Si sand casting and T6 heat treatment then welded together by TIG welding and finally assembled on the bottom chassis frame produced by using 6063 extrudes welded by 4000 series electrodes. The space frame chassis was studied by also computer simulation to test and see critical points which must be modified during manufacturing. Besides the experimental and theoretical studies, space frame was also produced at the same time. According to the experimental results, the feasibility of the production of lightweight and solid chassis structure was achieved.
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Samonds, M. T. "Finite element simulation of solidification in sand mould and gravity die castings." Thesis, Swansea University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384446.
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Gullapalli, Ram A. "A Study of Mixed Manufacturing Methods in Sand Casting Using 3D Sand Printing and FDM Pattern-making Based on Cost and Time." Youngstown State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1485335857475363.
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Snelling, Jr Dean Andrew. "A Process for Manufacturing Metal-Ceramic Cellular Materials with Designed Mesostructure." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/51606.
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The goal of this work is to develop and characterize a manufacturing process that is able to create metal matrix composites with complex cellular geometries. The novel manufacturing method uses two distinct additive manufacturing processes: i) fabrication of patternless molds for cellular metal castings and ii) printing an advanced cellular ceramic for embedding in a metal matrix. However, while the use of AM greatly improves the freedom in the design of MMCs, it is important to identify the constraints imposed by the process and its process relationships.
First, the author investigates potential differences in material properties (microstructure, porosity, mechanical strength) of A356 — T6 castings resulting from two different commercially available Binder Jetting media and traditional 'no-bake' silica sand. It was determined that they yielded statistically equivalent results in four of the seven tests performed: dendrite arm spacing, porosity, surface roughness, and tensile strength. They differed in sand tensile strength, hardness, and density.
Additionally, two critical sources of process constraints on part geometry are examined: (i) depowdering unbound material from intricate casting channels and (ii) metal flow and solidification distances through complex mold geometries. A Taguchi Design of Experiments is used to determine the relationships of important independent variables of each constraint. For depowdering, a minimum cleaning diameter of 3 mm was determined along with an equation relating cleaning distance as a function of channel diameter. Furthermore, for metal flow, choke diameter was found to be significantly significant variable.
Finally, the author presents methods to process complex ceramic structure from precursor powders via Binder Jetting AM technology to incorporate into a bonded sand mold and the subsequently casted metal matrix. Through sintering experiments, a sintering temperature of 1375 °C was established for the ceramic insert (78% cordierite). Upon printing and sintering the ceramic, three point bend tests showed the MMCs had less strength than the matrix material likely due to the relatively high porosity developed in the body. Additionally, it was found that the ceramic metal interface had minimal mechanical interlocking and chemical bonding limiting the strength of the final MMCs.Ph. D.
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Snelling, Dean Andrew Jr. "A Process for Manufacturing Metal-Ceramic Cellular Materials with Designed Mesostructure." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51606.
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The goal of this work is to develop and characterize a manufacturing process that is able to create metal matrix composites with complex cellular geometries. The novel manufacturing method uses two distinct additive manufacturing processes: i) fabrication of patternless molds for cellular metal castings and ii) printing an advanced cellular ceramic for embedding in a metal matrix. However, while the use of AM greatly improves the freedom in the design of MMCs, it is important to identify the constraints imposed by the process and its process relationships.
First, the author investigates potential differences in material properties (microstructure, porosity, mechanical strength) of A356 — T6 castings resulting from two different commercially available Binder Jetting media and traditional 'no-bake' silica sand. It was determined that they yielded statistically equivalent results in four of the seven tests performed: dendrite arm spacing, porosity, surface roughness, and tensile strength. They differed in sand tensile strength, hardness, and density.
Additionally, two critical sources of process constraints on part geometry are examined: (i) depowdering unbound material from intricate casting channels and (ii) metal flow and solidification distances through complex mold geometries. A Taguchi Design of Experiments is used to determine the relationships of important independent variables of each constraint. For depowdering, a minimum cleaning diameter of 3 mm was determined along with an equation relating cleaning distance as a function of channel diameter. Furthermore, for metal flow, choke diameter was found to be significantly significant variable.
Finally, the author presents methods to process complex ceramic structure from precursor powders via Binder Jetting AM technology to incorporate into a bonded sand mold and the subsequently casted metal matrix. Through sintering experiments, a sintering temperature of 1375 °C was established for the ceramic insert (78% cordierite). Upon printing and sintering the ceramic, three point bend tests showed the MMCs had less strength than the matrix material likely due to the relatively high porosity developed in the body. Additionally, it was found that the ceramic metal interface had minimal mechanical interlocking and chemical bonding limiting the strength of the final MMCs.Ph. D.
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Almaghariz, Eyad S. "Determining When to Use 3D Sand Printing: Quantifying the Role of Complexity." Youngstown State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1433778181.
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Gorsky, Daniel A. "Niyama Based Taper Optimizations in Steel Alloy Castings." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1316191746.
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Agacik, Ihsan Alp. "An Alternative Process Including Sand Casting, Forging And Heat Treatment Of 30mm Diameter X48crmov8-1 Tool Steel." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614962/index.pdf.
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Shear blades are mostly made of cold-work tool steels and manufactured by rolling process. Rolling process is performed not only for forming the tool but also for improving the mechanical properties.
In this study, an alternative method, involving sand casting, hot forging and heat treatment processes to manufacture the shear blades, has been proposed. In the proposed method, plastic deformation will be carried out by means of forging instead of rolling. The material has been selected as X48CrMoV8-1. For both of casting and forging processes, simulations have been conducted by using Computer Aided Engineering Software. According to the results of casting process simulation, the billets have been poured. These billets have been soft annealed first and then taken as the initial raw material for the forging process. After the forging process, quenching and tempering processes have been applied.
The specimens have been taken as cast, as forged and as tempered and the microstructural analysis and mechanical tests have been performed on these. The same tests and analysis have been repeated for a commercially available shear blade sample which is manufactured by rolling. All these investigations have shown that the properties of the forged shear blade are very similar to the rolled shear blade. Therefore, the new proposed method has been verified to be used as an alternative manufacturing method for the cold-work tool steel shear blades.
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Nyembwe, K., Beer D. De, der Walt K. Van, and S. Bhero. "Time and cost assessment of the manufacturing of tooling by metal casting in rapid prototyping sand moulds." Interim : Interdisciplinary Journal, Vol 10 , Issue 1: Central University of Technology Free State Bloemfontein, 2011. http://hdl.handle.net/11462/335.
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Published ArticleIn this paper the time and cost parameters of tooling manufacturing by metal casting in rapid prototyping sand moulds are assessed and comparison is made with alternative tool making processes such as computer numerical control machining and investment casting (Paris Process). To that end two case studies obtained from local companies were carried out. The tool manufacturing was conducted according to a five steps process chain referred to as Rapid Casting for Tooling (RCT). These steps include CAD modelling, casting simulation, rapid prototyping, metal casting and finishing operations. In particular the Rapid Prototyping (RP) step for producing the sand moulds was achieved with the aid of an EOSINT S 550 Laser Sintering machine and a Spectrum 510 Three Dimensional Printer. The results indicate that RP is the rate determining step and cost driver of the proposed tooling manufacturing technique. In addition it was found that this tool making process is faster but more expensive than machining and investment casting.
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Foley, Brian M. "A System for Detecting the Position of a Molten Aluminum Metal-Front within a Precision Sand Mold." Digital WPI, 2009. https://digitalcommons.wpi.edu/etd-theses/50.
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Manufacturers of cast metal parts are interested in the development of a feedback control system for use with the Precision Sand-Casting (PSC) process. As industry demands the ability to cast more complex geometries, there are a variety of challenges that engineers have to address. Certain characteristics of the mold, such as thick-to-thin transitions, extensive horizontal or flat surfaces, and sharp corners increase the likelihood of generating defective casts due to the turbulent metal-flow during fills. Consequently, it is critical that turbulent flow behavior within the mold be minimized as much as possible. One way to enhance the quality of the fill process is to adjust the flow rate of the molten metal as it fills these critical regions of the mold. Existing systems attempt to predict the position of the metal level based on elapsed time from the beginning of the fill stage. Unfortunately, variability in several aspects of the fill process makes it very difficult to consistently predict the position of the metal front. A better approach would be to embed a sensor that can detect the melt through a lift-off distance and determine the position of the metal-front. The information from this sensor can then be used to adjust the flow rate of the aluminum as the mold is filled. This thesis presents the design of a novel non-invasive sensor monitoring system. When deployed on the factory floor, the sensing system will provide all necessary information to allow process engineers to adjust the metal flow-rate within the mold and thereby reduce the amount of scrap being produced. Moreover, the system will exhibit additional value in the research and development of future mold designs.
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Samuels, Gregory James. "Measurement of gas evolution from PUNB bonded sand as a function of temperature." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/1260.
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The chemical binders used to make sand molds and cores thermally decompose and release gas when subjected to the high temperature conditions in sand casting processes. Computational models that predict the evolution of the binder gas are being introduced into casting simulations in order to better predict and eliminate gas defects in metal castings. These models require knowledge of the evolved binder gas mass and molecular weight as a function of temperature, but available gas evolution data are limited. In the present study, the mass and molecular weight of gas evolved from PUNB bonded sand are measured as a function of temperature for use with binder gas models. Thermogravimetric analysis of bonded sand is employed to measure the binder gas mass evolution as a function of temperature for heating rates experienced in molds and cores during casting. The volume and pressure of gas evolved from bonded sand are measured as a function of temperature in a specially designed quartz manometer during heating and cooling in a furnace. The results from these experiments are combined with the ideal gas law to determine the binder gas molecular weight as a function of temperature. Thermogravimetric analysis reveals that the PUNB binder significantly decomposes when heated to elevated temperatures, and the PUNB binder gas mass evolution is not strongly influenced by heating rate. During heating of PUNB bonded sand at a rate of 2°C/min, the binder gas molecular weight rapidly decreases from 375 g/mol at 115°C to 99.8 g/mol at 200°C. The molecular weight is relatively constant until 270°C, after which it decreases to 47.7 g/mol at 550°C. The molecular weight then steeply decreases to 30.3 g/mol at 585°C and then steeply increases to 47.2 g/mol at 630°C, where it remains constant until 750°C. Above 750°C, the binder gas molecular weight gradually decreases to 33.3 g/mol at 898°C. The present measurements are consistent with the molecular weights calculated using the binder gas composition data from previous studies. The binder gas is composed of incondensable gases above 709°C, and the binder gas partially condenses during cooling at 165°C if the bonded sand is previously heated below 507°C.
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Jorapur, Nikhil Sudhindrarao. "Design, Fabrication and Testing of Fiber-Reinforced Cellular Structures with Tensegrity Behavior using 3D Printed Sand Molds." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/84531.
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The overall goal of this work is to improve the structural performance of cellular structures in bending applications by incorporating tensegrity behavior using long continuous fibers. The designs are inspired by the hierarchical cellular structure composition present in pomelo fruit and the structural behavior of tensegrity structures. A design method for analyzing and predicting the behavior of the structures is presented. A novel manufacturing method is developed to produce the cellular structures with tensegrity behavior through the combination additive manufacturing and metal casting techniques.
Tensegrity structures provide high stiffness to mass ratio with all the comprising elements experiencing either tension or compression. This research investigates the possibility of integrating tensegrity behavior with cellular structure mechanics and provides a design procedure in this process. The placement of fibers in an octet cellular structure was determined such that tensegrity behavior was achieved. Furthermore, using finite element analysis the bending performance was evaluated and the influence of fibers was measured using the models. The overall decrease in bending stress was 66.6 %. Extending this analysis, a design strategy was established to help designers in selecting fiber diameter based on the dimensions and material properties such that the deflection of the overall structure can be controlled.
This research looks to Additive Manufacturing (AM) as a means to introduce tensegrity behavior in cellular structures. By combining Binder Jetting and metal casting a controlled reliable process is shown to produce aluminum octet-cellular structures with embedded fibers. 3D-printed sand molds embedded with long continuous fibers were used for metal casting. The fabricated structures were then subjected to 4 point bending tests to evaluate the effects of tensegrity behavior on the cellular mechanics. Through this fabrication and testing process, this work addresses the gap of evaluating the performance of tensegrity behavior. The overall strength increase by 30%. The simulation and experimental results were then compared to show the predictability of this process with errors of 2% for octet structures without fibers and 6% for octet structures with fibers.Master of Science
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Schaub, Henning. "Comparison of different aluminium casting processes from an environmental perspective : Case study on plaster mould castings produced in Mid Sweden." Thesis, Mittuniversitetet, Avdelningen för ekoteknik och hållbart byggande, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-35659.
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While Aluminium has lots of unique properties and is seen as a material of the future, its production and manufacturing has significant environmental impacts. For complex and dimensional shapes casting remains the main manufacturing method and in this study the environmental pressure of different casting techniques is compared. A screening LCA is conducted to determine the environmental impacts of plaster mould castings in a case study at the Ventana Hackås AB foundry in Mid Sweden. The findings are compared to models of sand, pressure die and lost wax castings, based on literature datasets. The most relevant factors for the environmental performance are identified as the production of the aluminium alloy and the amount and source of energy. For plaster mould castings additionally the plaster consumption is significant, while lost wax castings are dominated by the mould production and general processes. Under similar circumstances a relatively similar performance was found for all casting techniques except the lost wax process, which is at least 3 times more emission intensive. Of the remaining techniques pressure die castings performed the best and plaster mould castings the worst, but different sources of uncertainties have been identified in this comparison. In addition a carbon footprint interface is created based on these findings, to enable specific comparisons of different casting method setups. Customizable variables allow the adaptation of three scenarios to real world conditions. As the main influencing factors the aluminium alloy, source of electricity and casting technique have been identified.2018-10-10
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Ahmad, Nadiah. "Riser Feeding Evaluation Method for Metal Castings Using Numerical Analysis." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1447845668.
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Farhang, Mehr Farzaneh. "Quantitative assessment of the effect of copper chills on casting/chill interface behavior and the microstructure of sand cast A319 alloy." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43592.
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Although the demand for A319 alloy has increased in recent years, thermal fatigue resistance of the alloy is still one of the most important challenges in engine applications, especially in the newer generation of engines in which cylinder spacing has been reduced. According to the previous studies there are several parameters that improve thermal fatigue resistance such as: low SDAS, fine grain size, low porosity level, and low intermetallic content.
Cooling rate has a direct effect on the shape, size, and distribution of the microstructural phases, as well as on the scale of the dendrites, and pore size. High cooling rates can improve thermal fatigue resistance, as a result of fine microstructure and small pore size. On the other hand, thin sections of a mold may not properly fill and “Cold Shuts” may result, if high cooling rates are applied.
One approach to balance these phenomena is to use a water-cooled chill where water cooling is activated part way through the casting sequence. This type of chill causes a lower cooling rate initially, when the filling procedure is occurring, and after filling, the cooling rate increases to reduce the microstructure size. The results show that this method has the potential to both avoid cold shuts and miss-runs and improve the cast microstructure farther into castings remote from the chill.
A mathematical model has been developed in “ANSYS CFX 12.0” to evaluate the effectiveness of this concept quantitatively. The model simulates the behavior of the Casting/chill interface and also predicts the cooling rates resulting from different casting conditions when using solid chill and water-cooled chill.
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Rodomsky, Caitlyn Marie. "Surface Finish on A356-T6 Cast Parts using Additive Manufactured Sand Molds." Youngstown State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1526030093287334.
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Lu, Yan. "Predicting and Validating Multiple Defects in Metal Casting Processes Using an Integrated Computational Materials Engineering Approach." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1562346439311635.
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Cimatti, Federico. "Progettazione del processo fusorio per la realizzazione di cilindro per motore a combustione interna a due tempi." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16429/.
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Progettazione di un cilindro per motori a combustione interna a due tempi, da impiegarsi come parte di ricambio per propulsori monomarcia costruiti da Piaggio s.p.a. e da Motori Minarelli s.p.a.
Approfondimenti su scelta del materiale (lega di alluminio), definizione del processo fusorio, analisi FEM della colata, nonché sulla costruzione delle attrezzature necessarie alla messa in produzione.
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Prada-Echevarría, Luz, Jorge Chinchay-Grados, Fernando Maradiegue-Tuesta, and Carlos Raymundo. "Production Control Model Using Lean Manufacturing Tools and Kanban/CONWIP Systems to Improve Productivity in the Process of Sand Casting in a Heavy Metalworking SME." Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/653783.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.The contribution of the metalworking sector to the gross domestic product is decreased by 8.6% in the 2017–2018 period because of problems such as high rejection rates, lead times, and raw material losses. Consequently, the sector’s production was reduced by PEN 1,200,000 while demand remained flat. Thus, this article proposes a production control model using 5S, Single-Minute Exchange of Dies, and tools such as Kanban and Constant Work-in-Progress (CONWIP) to increase the productivity of a sand casting line in a Peruvian metalworking enterprise that manufactures parts for mining on request. The improvement proposal involves the implementation of lean manufacturing tools and analyzes low productivity effects. The problems identified are typical of the Peruvian metalworking sector; thus, this study may contribute to finding possible solutions for issues faced by other enterprises.
Revisión por pares
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Kålås, Øystein Heden. "Patternless direct moulding of sand castings." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produktutvikling og materialer, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12957.
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Mitra, Saptarshee. "Experimental and numerical characterization of functional properties of sand molds produced by additive manufacturing (3D printing by jet binding) in a fast foundr." Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0043.
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Les techniques traditionnelles pour la production des moules et des noyaux en sable utilisés en fonderie pour la coulée de métaux sont actuellement en cours de remplacement par des méthodes de fabrication additive, afin d'aider l’industrie aérospatiale/automobile à fabriquer des pièces de forme complexe d'une manière pratique. Le but de ce travail de recherche est d'étudier les propriétés fonctionnelles des moules imprimés en 3D utilisés lors de la coulée des pièces de forme complexe pour des applications d'ingénierie. Premièrement, le comportement mécanique des moules en sables imprimés en 3D a été analysé et caractérisé pour de différents paramètres du processus d'impression. Ensuite, les propriétés mécaniques et de transport de masse des moules en sable 3DP ont été étudiées. Les pièces imprimées en 3D pour la fonderie sont souvent fabriquées avec un type de technologie de fabrication additive appelé « powder-binder-jetting process » (processus de projection de liant de poudre). Des mesures sur trois points de la force de flexion, la densité, la porosité et la perméabilité, ont été effectués sur les moules fabriqués avec la technologie additive. En plus, l’influence de la température et de la fraction volumique du liant sur les propriétés mécaniques et de transport de masse a également été étudiée. Par ailleurs, la perméabilité des moules en sable imprimé a aussi été caractérisée par micro-tomographie de rayons X, permettant la modélisation avancée de la microstructure poreuse en suivant plusieurs étapes : 1) tomodensitométrie de petits échantillons de moules 3DP, 2) reconstruction volumétrique 3D de données, 3) simulation numérique pour la prédiction de la perméabilité à partir de volumes reconstruits et 4) modélisation du réseau de pores pour déterminer la distribution de la taille des pores et des constrictions. Des expériences ont également été conçues pour étudier les moules imprimés en 3D en termes de leur érosion lors de la coulée des métaux. Cela a permis d’identifier les paramètres optimaux du procédé d’impression 3D des moules, non seulement en termes de leurs propriétés mécaniques et de transport de masse, mais aussi pour minimiser l'érosion du moule durant la coulée métallique. Une méthode de détermination de la résistance à l'érosion des moules en sable a également été proposée, sur la base de la mesure du volume de la surface érodée à l'aide d'une technique d'ingénierie inverse moderneNowadays, traditionally manufactured sand molds and cores for metal casting are being progressively replaced by additively processed sand molds in aerospace/automotive industry, facilitating the production of quality cast parts with complex shapes. The type of additive manufacturing technology used to manufacture 3DP parts in foundries is known as powder-binder-jetting process. In this technology, the molds are produced without the use of any kind of additive tools and in a completely automated way using the layer based construction method. One of the most popular binder systems used in the manufacturing of 3DP mold is a furan-based resin binder, which holds the grain particles together. Their amounts and ratios can influence significantly the 3D printed mold properties, affecting casting quality. Therefore, it is essential to characterize the effects process parameters on the functionality of the 3DP molds. In the present work, the mechanical behavior of 3DP sand molds with varying printing process parameters was first investigated, followed by mass transport properties. To do so, a series of three-point bending strength tests, density measurements, porosity measurements and permeability tests were performed on the 3DP molds. Furthermore, the influence of time, temperature and binder volume fraction on the mechanical and mass transport properties was also investigated. Advanced modelling of the pore space was performed by using the reconstructed images provided by X-ray computed tomography, following different steps: X-ray CT scanning of small 3DP mold specimen, 3D volumetric reconstruction of data, numerical simulations for the prediction of permeability from the reconstructed volume, and pore network modelling for the determination of the pore size distribution. Experiments were also designed to investigate the 3D printed molds in terms of mold erosion during metal casting, in order to select the molding parameters to print 3D printed parts not only with good mechanical and mass transport properties but also to minimize the mold erosion during metal casting. Furthermore, a reverse engineering method for determination of the erosion resistance of sand molds has been established, to study the volume of the eroded surface
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Lindqvist, Olle, and Gustaf Thulin. "Gjutning av rostfritt stål med 3D-printade sandformar." Thesis, Uppsala universitet, Industriell teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413840.
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Sand mold casting is a manufacturing method that has been used for thousands of years. In recent years additive manufacturing has, among other things, enabled production of sand molds with complex geometry resulting in castings with geometry that would have been very hard, if not impossible, to produce with conventional sand mold casting or machining procedures. Since this manufacturing method is relatively new, knowledge gaps exist regarding the benefits and drawbacks of the method as well as when it should be used. The purpose of this study has been to explore casting molds produced by additive manufacturing, how they can be used and what effect they have on the manufactured product. For this purpose, a existing product has been redesigned to be cast in one of these molds instead of traditionally being machined from large aluminium blocks. The design work has been supplemented with calculations on the parts structural integrity, interviews and material sample tests. The redesign was made on behalf of Vattenfall AB and the studied component was a part of a test rig for a hydro power plant called spiral casing. The result of the study is a new design of the spiral casing with a lower weight and volume, made with stainless steel instead of aluminium, and other improvements. Testing of cast samples have shown that the mechanical properties of steel cast in 3D-printed and conventionally manufactured sand molds do not differ significantly. The sample cast in a 3D-printed mold did have a finer surface finish however. Production volume, product complexity, material and lead time are all factors that determine when additive manufacturing should be used in the creation of sand molds. Further studies are required to better determine where the breakeven points are.
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Jomaa, Ghassan. "Étude des dégagements gazeux survenant pendant la coulée de pièces d’Aluminium." Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0068.
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La fabrication de pièces automobiles en aluminium des formes complexes telles que les culasses de moteur par le procédé de fonderie est effectuée par l'insertion de noyaux en sable durci par des résines (liants) organiques dans un moule métallique et la coulée d'un métal en fusion dans ce moule. Sous l'effet de la température élevée du métal, les résines organiques se décomposent et produisent des dégagements gazeux qui altèrent la qualité des pièces à fabriquer. Jusque tout récemment, la maîtrise des dégagements gazeux survenant pendant le procédé du moulage était basée sur des essais expérimentaux. L'objet du présent travail est d'étudier les dégagements gazeux par simulation numérique. Pour ce faire, nous avons proposé plusieurs modèles numériques. Nous avons introduit un modèle cinétique pour la décomposition thermique des résines organiques. Nous avons développé un modèle général d'écoulements multiphasiques en milieux poreux en utilisant la méthode de prise de moyenne volumique. Quatre modèles de dégagements gazeux, représentant l'écoulement et le transport de gaz dans le noyau sous différents scénarios, sont donnés à partir du modèle général. Des modèles sont également développés pour décrire le couplage de transferts thermiques dans le moule et la pièce à fabriquer avec les dégagements gazeux dans le noyau. L'implémentation des différents modèles dans le logiciel libre OpenFOAM a permis d'obtenir un outil de simulation capable de simuler les dégagements gazeux sous différents scénarios et d'étudier l'impact de plusieurs facteurs tels que le type des résines, la forme de noyau, la perméabilité de sable sur l'évolution de la pression du gaz dans le noyauThe manufacture of automotive aluminum parts with complex shapes such as cylinder heads of the engine by the casting process is carried out by the insertion of cores made with sand hardened using organic resins (binders) in a metal mold and pouring of molten metal in this mold. As a result of the high temperature of poured metal, organic resins undergo thermal decomposition (pyrolysis) and produce gases which impair the quality of the parts to be manufactured. Until recently, the study of gas emissions occurring during the casting process was based on experimental tests. The purpose of this work is to study the gas emissions by numerical simulation. To do this, we proposed several numerical models. We introduced a kinetic model for the thermal decomposition of organic resins. We have developed a general model of multiphase flow in porous media using the method of volume averaging. Four models of gas emissions representing flow and transport of gas in the core under different scenarios are given from the general model. Models are also developed to describe the coupling of the heat transfer in the mold and the casting with gas emissions in the sand core. The implementation of the various models in the free software OpenFOAM provides a simulation tool that allows to simulate gas emissions under different scenarios and to study the impact of several factors such as the type of resins, core shape, the permeability of the sand on the evolution of the pressure of gas in the core
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Hermansson, Jakob, and Emma Wahlström. "Materialval för minskat slitage av sandformningsverktyg." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-13776.
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På Volvo Group Trucks Operations (GTO) i Skövde tillverkas cylinderblock, cylinderhuvud och svänghjul genom gjutning med sandformar. Då formverktygen som formar sandformarna fylls uppkommer slitage där sandpartiklarna träffar, vilket leder till att formverktygen behöver underhållas regelbundet.Målet med denna studie är att hitta alternativa material som formverktygen kan tillverkas i alternativt förstärkas eller beläggas med för att minska slitaget i formverktygen och på så sätt minska kostnader genom att förlänga underhållsintervallen. Problemet analyseras och en litteraturstudie kring erosiv och abrasiv nötning genomförs.Ett antal material tas fram genom en materialvalsprocess som lämpliga kandidater baserat på litteraturstudien, materialkartor och diskussion. Materialprover testas med en standardmetod för erosion med gasburna partiklar. Resultat från tidigare empiriska studier tyder på att erosion påverkas starkt av materialegenskaper så som hårdhet och seghet men även de eroderande partiklarnas infallsvinkel och hastighet.Erosionstestet utförs för 30 och 90 graders infallsvinkel. Testet visar att de mjukare stålen, Holdax och Sverker 21, har högre beständighet mot erosion vid låga infallsvinklar och det hårdare stålet Nimax har högre beständighet vid höga infallsvinklar. Nimax anses vara ett lämpligt material till formverktyget då Nimax har den totalt lägsta erosionstakten vid hopslagning av den totala erosionstakten över båda infallsvinklarna. Nimax har den lägsta erosionstakten vid 30 graders infallsvinkel och anses även ha god beständighet mot erosion vid 90 graders infallsvinkel.Rekommendation ges kring upprepade erosionstester för att säkerställa resultatet. Rekommendationer finns också kring materialprovning i formverktyget för att se om ett materialbyte skulle leda till besparingar. Undersökning av möjligheter att konstruera bort nötning i formverktyget genom ändring av infallsvinklar mellan den inblåsta sanden och formverktyget, samt ändring av lufttryck rekommenderas.At Volvo Group Trucks Operations (GTO) in Skövde, cylinder blocks, cylinder heads and flywheels are manufactured through sandcasting. As the forming tools that forms the sand forms are filled with sand, wear occurs where the sand particles hit the tool surface. The forming tool thus needs to be regularly maintained. The aim of this study is to evaluate alternative materials that the forming tools can be manufactured in to reduce wear, and thereby reducing costs by extending maintenance intervals. The problem is analyzed and a literature study on erosive and abrasive wear is carried out. A number of materials are presented as suitable candidates based on the literature study, material charts and discussion. Material samples are tested using a standard method for solid particle erosion using gas jets. Results from previous empirical studies indicate that erosion is strongly influenced by material properties such as hardness and toughness but also the angle of impingement and velocity of the erosive particles.The erosion test is performed at 30 and 90 degree angle of impingement. The test shows that the softer steel, Holdax and Sverker 21 have higher resistance to erosion at low angles of impingement and the harder steel Nimax has higher resistance at high angles of impingement. Nimax is considered a suitable material for the forming tool, as Nimax has the overall lowest erosion rate when adding the total erosion over both angles of impingement. Nimax has the lowest erosion rate at 30 degrees angle and is also considered to have good resistance to erosion at 90 degrees angle. Recommendation is given on repeated erosion tests to validate the results. There are also recommendations regarding material testing in the forming tool to see if a material change would lead to savings. Examination of possibilities to make changes in the sand filling process, altering angle of impingement between the sand blown and the forming tool as well as air pressure is recommended.
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Blaha, Marek. "Optimalizace výroby litinových odlitků za účelem snížení výskytu vad." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231936.
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The presented diploma thesis is focused on defects of castings as well as optimization of production with the aim of reducing the number of defective products. The theoretical part is focused on basic information about cast iron and its production, structure and mechanical properties. Another part of this thesis describes the defects of castings and options for non-destructive testing of cast iron castings. In the experimental part are analyzed three sorts of defective casting. Castings for testing were provided by JMA s.r.o. foundry. The summary contains tests results and proposals for optimization of production.
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Vašek, Vojtěch. "Použití modelů zhotovených technologii 3D tisku při výrobě odlitků do bentonitových forem na formovací lince." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-319282.
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Shortening of the time required to make first product after demand is a crucial factor in every field of industry, not excluding the foundry. To lower this delay, there are rapid prototyping methods. The aim of this thesis is to execute an experiment and then evaluate possibilities of using patterns made by 3D FDM printer on an automatic molding line.
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Bargaoui, Hiba. "Simulation de la déformation des noyaux de fonderie durant la coulée." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM004/document.
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Les cavités intérieures des culasses d'aluminium sont réalisées à l'aide de noyaux de sable, qui sont constitués d'un mélange de silice et d'une résine Polyuréthane. Ils sont placés dans le moule métallique juste avant la coulée. Durant celle-ci, ils subissent la pression métallo-statique et sont soumis à des températures élevées. Sous ces conditions extrêmes, avec l'apparition de parois de plus en plus fines et de formes plus complexes, les noyaux peuvent présenter des déformations qui induisent des défauts dimensionnels sur les pièces finales.Pour contrôler la déformation des noyaux, il faut d'abord disposer d'une caractérisation robuste de leur propriétés thermiques et mécaniques, qui puisse être utilisée dans des calculs de structures simulant le flux de métal liquide, la solidification et les champs thermiques. Cette approche n'est pas encore pratiquée de façon complète dans l'industrie. Une revue de la littérature confirme que cette connaissance n'est que très parcellaire pour le moment.Le travail a donc d'abord été concentré sur la caractérisation expérimentale du comportement thermomécanique et des propriétés thermophysiques des noyaux de fonderie et du liant résine.Ensuite, un modèle de comportement capable de prendre en compte la viscosité du matériau, son endommagement, et surtout son évolution en fonction du temps et de la température en raison de la dégradation thermique du liant résine a été développé.Une éprouvette technologique a finalement été conçue et un protocole expérimental a été mis en place pour mesurer la déformation d'un noyau durant la coulée et de valider numériquement le modèle de comportement sous des chargements thermiques et mécaniques complexesThe inner cavities of aluminum cylinder heads are made using sand cores, which are made of silica sand and of a polyurethane resin binder. The cores are placed in the metallic mold just before casting. During this stage, the cores are submitted to the metallo-static pressure and high temperatures. Under these extreme loading conditions, with the development of thinner and thinner walls with complex designs, the cores exhibit significant deformation causing dimensional defects in the final cast.To control the deformation of the sand core, it is necessary to possess a robust characterization of their thermal and mechanical properties, that could be introduced in structural computations simulating the flow of the liquid metal, the solidification and the thermal fields. This approach is still not fully in use in the industry. A review of the literature confirms that this knowledge is incomplete for the moment.The work was therefore concentrated on the experimental characterization of the thermomechanical behavior and the thermophysical properties of the foundry cores and Polyurethane resin binder.Then, a behavior model capable of taking into account the viscosity of the material, damage development, and especially its evolution as a function of time and temperature because of the thermal degradation of the binder resin was developed.A technological specimen was finally designed and an experimental protocol has been established to measure the deformation of a core during casting and numerically validate the constitutive equations under complex thermal and mechanical loadings
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Galles, Daniel Joseph. "Prediction of distortions and pattern allowances in steel sand castings." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2077.
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Modeling the thermomechanical behavior of the bonded sands used for steel sand casting is of great importance for the prediction of distortions and pattern allowances. In this study, distortions created by mechanical interactions between the casting and sand mold are measured from two experimental setups and then predicted by finite element stress analyses. The casting geometries involve a hollow cylinder for the first experiment and U-shaped bracket for the second. The temporal evolutions of 1) the cylinder’s inner diameter and 2) the gap opening between the bracket legs are measured in situ utilizing LVDTs (Linear Variable Differential Transformers) connected to quartz rods. The considerable distortions measured during the cylinder and bracket experiments are mainly caused by core expansion and core restraint, respectively. For the simulations, a one-way temperature-displacement coupling is adopted, in which temperatures are predicted using commercial casting simulation software and then used as inputs for the finite element stress analyses. The steel is modeled as an elasto-visco-plastic material, whereas the Drucker Prager Cap model is employed for the bonded sand. It is found that sand dilation (i.e., the volumetric expansion of a granular media due to a shear force) must be considered for the cylinder experiments. Otherwise, the inner diameter expansion observed during solidification is far under-predicted. For the bracket, a crack plane must be included in the stress simulation model. If not, the outer mold restrains the bracket legs from being pushed outward and distortions are under-predicted. By matching the predicted displacements with the measurements, a constitutive dataset for bonded sands is developed, whose predictive capability is then demonstrated through a case study.
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Souza, Josiane Carneiro. "REUTILIZAÇÃO DE AREIA A VERDE DESCARTADA DE FUNDIÇÃO LIGADA COM Na2SiO3.XH2O/CO2 NA PREPARAÇÃO DE MOLDES NÃO PERMANENTES." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2012. http://tede2.uepg.br/jspui/handle/prefix/1425.
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The manufacture of metal parts by molding and molded by the process in the green sand (sand base crowded with clay) is widespread in industries for its low cost and operational flexibility. A major advantage is that the materials can be reused in new molding cycles. However, when the liquid metal comes in contact with the mold, causes disabling clay locally, generating inert materials that focus on the sand and limit long cycles of reuse. Thus, there are surplus sands by adding new primary materials and the consequent need for disposal to maintain the constant flow of materials. This excess is a liability that is usually discarded in landfills. This study sought a solution to this environmental waste, by reuse in the actual molding process using the sodium silicate (Na2SiO3.XH2O)/CO2, as binder. The properties obtained from samples with waste foundry sands (WFS) and with the new green sands were compared to verify the real potential for reuse WFS and the effect of its inert components and additives. For this purpose it was evaluated the mechanisms involved in the interaction with the green sand silicate before and after reaction with CO2 in the range of 0 to 20% (by weight) mixed. Mechanical properties were evaluated before and after gassing with CO2, both with WFS and with its primary components. In this study, for microstructural characterization techniques were used for X-ray diffraction, optical microscopy and MEV/ EDS. The results showed mutually dependent mechanical properties, the morphology of the silica gel coating on the sand grains, and the composition of the mixture used.
A fabricação de peças metálicas por fundição e moldadas pelo processo em areias a verde (areia base aglomerada com argila) é bastante difundida nas indústrias pelo seu baixo custo e flexibilidade operacional. Uma das grandes vantagens é que os materiais utilizados podem ser reutilizados em novos ciclos de moldagem. Porém, quando o metal líquido entra em contato com o molde, provoca a desativação da argila localmente, gerando materiais inertes que se concentram na areia e limitam ciclos longos de reuso. Com isto, surgem excedentes de areias pela adição de materiais primários novos e a consequente necessidade de descarte para manter o fluxo constante de materiais. Este excedente é um passivo que normalmente é descartado em aterros. Este trabalho buscou uma solução ambiental para este resíduo, por meio da reutilização no próprio processo de moldagem, utilizando silicato de sódio (Na2SiO3.XH2O)/CO2, como ligante. As propriedades obtidas de amostras com areias descartadas e com as areias a verde novas foram comparadas entre si para verificar o real potencial de reutilização da ADF e o efeito de seus componentes inertes e aditivos. Para esta finalidade avaliou-se os mecanismos envolvidos na interação da areia a verde com o silicato, antes a após reação com CO2, na faixa entre 0 a 20% (em peso) nas misturas. Propriedades mecânicas foram avaliadas antes e após a gasagem com o CO2, tanto com areia descartada de fundição (ADF) quanto com os seus componentes primários. Neste estudo, para caracterização microestrutural foram utilizadas técnicas de Difração de raios X, Microscopia Ótica e Microscopia Eletrônica de Varredura/EDS. Os resultados demonstraram dependência mútua entre as propriedades mecânicas; a morfologia do recobrimento da sílica gel sobre os grãos de areia; e a composição da mistura utilizada.
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Petzold, Lukas. "Gefüge-Eigenschaftsrelationen dünnwandig erstarrter Eisenlegierungen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-67668.
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Gegenstand der Arbeit ist die Untersuchung der Gefügebildung dünnwandig erstarrter Eisenlegierungen und deren Auswirkung auf die mechanischen Eigenschaften. Die Arbeit ist in zwei Teile untergliedert. Im experimentellen Teil wurden Stahlgusslegierungen unter Variation ihrer
Zusammensetzung erschmolzen und in Quarzsandformen vergossen. Das erhaltene Probenmaterial wurde im Gusszustand sowie nach optional angewendeten Wärmebehandlungen untersucht. Die Abhängigkeiten zwischen chemischer Zusammensetzung, Gefügeausbildung und
mechanischen Eigenschaften wurden quantitativ dargelegt. Der Modellierungsteil enthält die Ergebnisse der Simulation des Gieß- und Erstarrungsprozesses eines ausgewählten Stahlgusswerkstoffs.
Zur Durchführung der Simulation kamen kommerziell verfügbare Softwarepakete zum Einsatz. Die Ergebnisse wurden mit experimentell ermittelten Daten verglichen und die Adäquatheit der Simulation beurteilt. Die Anwendbarkeit der genutzten Simulationsmethoden auf den Bereich dünnwandiger Stahlgussteile wurde aufgezeigt.
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Nováková, Lucie. "Snížení nákladů na výrobu odlitků ze slitin hliníku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-228993.
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This thesis deals with solving the most serious internal defects in castings made of aluminum alloys which are cast in sand molds in Slévárna a modelárna Nové Ransko Ltd. The problem solving contains a description of the problematic castings with the investigation of the structure and phases and subsequent detailed analysis of their production. The Author of this thesis also examines the influence of Fe and Mn on a possible formation of the internal porosity with the help of test meltings with the evaluation of the internal structural change. The Author’s design solution is a close checking of chemical composition with regard to the ratio Mn / Fe present in the alloy, the purchase of Foundry Degassing Unit to reduce gassiness of melted metals and better control of gassiness with the help of the appropriate equipment for the density Dichte index.
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Staňková, Markéta. "Hodnocení porezity u odlitků gravitačně litých z Al slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228043.
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Solving of this diploma thesis is evaluation porosity in sequence on mechanical properties from different Al alloys. Castings were made by gravity casting to the iron-mould or gravity casting to the sand. Measurements (mechanical properties, porosity, DAS - dendrite arm spacing, shape factors and sphericity) were statistically analysed and dependencies which were detected were processed to the graphs.
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Moosbrugger, John C. "Numerical computation of metal/mold boundary heat flux in sand castings using a finite element enthalpy model." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/16365.
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Скрипник, О. В., В. В. Клименко, В. В. Свяцький, С. В. Конончук, O. Skrypnyk, V. Klymenko, V. Sviatskyi, and S. Kononchuk. "Перспективи розвитку способу виготовлення піщаних форм по льодяним моделям." Thesis, ЦНТУ, 2017. http://dspace.kntu.kr.ua/jspui/handle/123456789/7032.
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Розглянуто застосування кріогеніки для одержання металевих виливків у піщаних формах для реалізації маловідходної і безвідхідної технології з повторним використанням формувальних матеріалів. The use of cryogenics for metal castings production in sand forms for the implementation of low-waste and non-waste technology with the repeated use of molding materials is considered.
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Descamps, Michel. "Le Coulage en bande et ses applications. Influence des caractéristiques granulaires des poudres céramiques sur les propriétés des bandes." Valenciennes, 1996. https://ged.uphf.fr/nuxeo/site/esupversions/a11c962c-8384-4282-a070-bba98c0d7a5d.
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L'évolution des propriétés physiques, mécaniques et de surface de matériaux élaborés par coulage en bande (AlN, Al#2O#3) est étudiée en fonction de la concentration de la phase organique utilisée et des caractéristiques poreuses de la bande (volume poreux, diamètre des pores ouverts). Ces propriétés sont régies par les propriétés intrinsèques de la phase organique, le taux de remplissage de la structure poreuse par les composés organiques et le diamètre de la porosité ouverte. Une application originale du coulage en bande est montrée au travers de l'élaboration de cibles d'oxydes multicouches, pour la réalisation de dépôts par pulvérisation cathodique radio-fréquence magnetron. Des cibles constituées de bandes de différents oxydes à pulvériser, (PbO/TiO#2, PbO/TiO#2/ZrO#2), ont permis une obtention rapide de dépôts de titanate de plomb et de titanate zirconate de plomb. La composition chimique désirée est obtenue par l'ajustement des épaisseurs des bandes d'oxydes constitutives des cibles
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Palma, Cruz Blanca Marlen Anaid. "Acción colectiva e instituciones en el uso, acceso y castigo de los recursos forestales maderables en la comunidad de San Francisco Tlalcilalcalpan." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2015. http://hdl.handle.net/20.500.11799/25597.
Full textAbstract:
Contiene esquemas, tablas e imágenes del lugarAnte esta problemática, surge la propuesta del manejo institucional de los recursos con base comunitaria, que trata de establecer un vínculo directo entre los objetivos de conservación y las necesidades locales al implementar reglas de uso que especifiquen formas de extracción y aprovechamiento, sin embargo, un verdadero manejo sustentable de los recursos requiere de un enfoque más incluyente y complejo, que vincule sin excepción a todos los niveles de organización política y no sólo al comunitario. A partir de esta noción, el presente trabajo de investigación analiza el caso del Ejido ―San Francisco Tlalcilalcalpan‖ desde las perspectivas teóricas de acción colectiva e instituciones para el manejo de los recursos forestales maderables. El propósito es enfatizar el papel que desempeñan las instituciones informales y la relación que mantienen con las instituciones formales; se trata de analizar a partir de un caso empírico, las reglas de operación que los ejidatarios han adoptado a partir de usos y costumbres, y repercuten en el cuidado, preservación y mantenimiento de los recursos forestales.
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Guillen, Gabrielle S. "Daughters of the Alcaldes: Women of Privilege in Medieval Burgos." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1399563719.
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Lin, Wen-Bin, and 林文彬. "Simplify Modeling of Sand Casting." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/82762145544432448164.
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