To see the other types of publications on this topic, follow the link: High pressure die casting.
Dissertations / Theses on the topic 'High pressure die casting'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'High pressure die casting.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Long, A. D. "Extending life of High Pressure Die Casting Dies." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527834.
Full text
2
Sivertsen, Halses Sebastian. "Die life prediction using High Pressure Die Casting simulations." Thesis, Tekniska Högskolan, Jönköping University, JTH, Material och tillverkning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-50031.
Full textAbstract:
Global trends in automotive industry for weight reduction drives an interest for casting of structural aluminum parts. High pressure die casting (HPDC) is chosen for this purpose since it enables manufacturing of large series parts where complexity and repeatability is demanded. Aluminum alloys have hence been developed through the years to obtain suitable mechanical properties for high strength parts. These alloys have been investigated to predict the types of potential failure mechanisms during HPDC in order to determine die life through simulations. Die life prediction was performed through simulations in MAGMAsoft 5.4 with the help of a die life module, which is based on thermal stresses generated in the die material during casting cycles. Fatigue data at elevated temperature obtained from literature review of AISI H11 tool steel was complemented to the Wöhler curve in the software database. Comparison of two aluminum alloys showed that chemical composition had a major influence on die life. Chemical composition had a direct impact on solidification time and with longer solidification time, the thermal load on the die increased. Since the stress range on the die is temperature dependent, the ability of heat transfer over time proved to be critical for die life results. The most crucial process parameter to achieve a longer die life was constant cooling by tempering channels, due to their high potential to remove heat. Tempering channels and die spray also prevent the die from exceeding a critical temperature resulting in soldering formation. Mold erosion was consistently observed in the same location for all simulations.
3
Sadeghi, Mohammad. "Optimization product parts in high pressure die casting process." Licentiate thesis, Mälardalens högskola, Framtidens energi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-27733.
Full textAbstract:
This thesis describes optimization of die temperature in high pressure die-casting (HPDC) of A380 alloy by experimental observation and numerical simulation with the use of statistical tools. The goal of this research is to determine the optimum die temperature to minimize incidence of these defects and thus maximize production of parts without defects. In HPDC, molten metal is injected into the die at high speed (40-60 m/s for aluminum alloys). Die temperature plays an important role on the rate of rejected parts. Therefore, flow patterns of molten metal in HPDC of an automotive component with very complex geometry (the ladder frame from the EF7 motor) were examined to determine the optimal die temperature. Defects in the production process fall into three categories, including surface, internal and dimensional defects. Samples produced in the experiments were classified according to any present defects. Another important parameter that influences casting defects is the cooling rate. Die temperatures were measured at the initial step and final filling positions. Experiments were performed with die temperatures ranging from 150 °C to 250 °C. The results show that the melt temperature difference in the die between the initial step and the final filling position was between 20 and 25 °C. Statistical tools such as regressions, relationships, max, min, correlations, ANOVA, T-test, Principal Component Analysis (PCA) and descriptive statistics were used to facilitate interpretation of data from the die-cast experiments. Perform some case studies in order to study the process behavior, take a better knowledge of effective parameters, and measure the required parameters. The collected data are utilized to: Set the model Validate/ verify the model ProCast software was used to simulate the fluid flow and solidification step, and the results were verified by experimental measurements. The optimal die temperature for this alloy was found to be above 200 oC. Statistical analysis of the experimental results found that defects were minimized and confirmed parts were maximized in HPDC of the ladder frame within a die temperature range of 210° C to 215° C.
4
Elfakharany, Essameldin F. "Qualitative Reasoning for filling pattern in high-pressure die-casting and gravity-driven casting /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192447430967.
Full text
5
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.
Full text
6
Fiorese, Elena. "Process parameters affecting quality of high-pressure die cast aluminium alloys." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3426773.
Full textAbstract:
High pressure die casting (HPDC) is a widely used process for manufacturing components with high production rate and complex geometries. However, high pressure die casting is still considered a “defect generating process”, since an amount of 5-10% of scrap is usually detected in castings. For this reason, the availability of new standards and tools for optimizing the process is one of the prominent needs of foundry field.
Both these issues are tackled in this Thesis. First, a new classification of defects and reference dies for estimating the static mechanical properties of aluminium alloys have been developed and then published as CEN Technical Reports, satisfying the need for new standards. Then, a novel and comprehensive methodology has been developed for optimizing HPDC process through the definition of meaningful behavioural models. Some newly defined process parameters have been hence introduced, by representing the most important physical phenomena affecting casting quality and the integral nature of HPDC, and an original approach is outlined. In particular, in order to provide an effective representation of the different process stages, the following parameters have been found to be more influential and effective in representing transmitted forces, mechanical energy exchange and heat removal: the root mean square acceleration in the second stage, the energy associated to the flow forces in the whole cycle, the work of the pressure forces in the third stage and the normalized thermal gradient. The first two parameters embody the plunger motion time-history, the third parameter represents the hydraulic pressure time-history, while the last one concentrates on some thermal aspects. These parameters take advantage from signal processing techniques of the measured position and pressure profiles. Four experimental campaigns (in the whole 210 castings) using different injection machines, different alloys and different geometries of the die have been carried out to validate the novel process parameters and to prove the general validity of the approach.
The statistical correlation with the measured static mechanical properties, density and percentage of porosity, as well as the metallographic analysis (percentage of oxides on fracture surfaces, analysis of different kinds of internal defect) prove the soundness of the developed method.
Given the significance of the plunger motion profile in explaining the casting quality, analytical models for computing the root mean square acceleration and the energy associated to the flow forces have been developed. These analytical models permit selecting in advance the best plunger motion profile, which guarantees reliability and soundness of castings, thus satisfying the need expressed by foundries for effective optimization tools.La pressocolata è un processo ampiamente utilizzato per produrre componenti con elevata produttività e geometria complessa. Comunque, la pressocolata è ancora considerata un “processo generatore di difetti”, dal momento che una percentuale del 5-10% di scarto è rilevata di solito nei getti. Per questa ragione, la disponibilità di nuovi standard e strumenti per l’ottimizzazione di processo è uno dei bisogni più importanti del settore della fonderia. Entrambe queste criticità sono affrontate in questa Tesi. Per prima cosa, è stata sviluppata e successivamente pubblicata come Report Tecnici riconosciuti dal CEN una nuova classificazione dei difetti e degli stampi di riferimento per stimare le proprietà meccaniche statiche delle leghe di alluminio, rispondendo al bisogno di nuovi standard. Poi, è stata sviluppata una metodologia nuova e completa per ottimizzare il processo di pressocolata attraverso la definizione di metamodelli significativi. Quindi, sono stati introdotti dei nuovi parametri di processo, che rappresentano i più importanti fenomeni fisici che influenzano la qualità dei getti e la natura integrale del processo di pressocolata, ed è stato delineato un approccio originale. In particolare, allo scopo di fornire una rappresentazione efficace delle diverse fasi del processo, si è dimostrato che i seguenti parametri sono i più influenti ed efficaci nel rappresentare le forze trasmesse, il flusso di energia meccanica e l’asportazione del calore: il valore quadratico medio dell’accelerazione in seconda fase, l’energia associata alle forze di flusso nell’intero ciclo, il lavoro delle forze di pressione nella terza fase e il gradiente termico normalizzato. I primi due parametri descrivono l’effetto del profilo di moto del pistone; il secondo è invece legato anche alla pressione esercitata dal pistone stesso, mentre l’ultimo rappresenta esclusivamente fenomeni di natura termica. Lo sviluppo ed il calcolo di questi parametri sfrutta le tecniche di elaborazione numerica dei segnali, al fine di estrarre le informazioni dai profili misurati di posizione e di pressione del pistone. La validazione del metodo proposto è stata condotta attraverso quattro diverse campagne sperimentali, con un totale di 210 getti analizzati, nelle quali sono state utilizzate diverse macchine di iniezione, diversi stampi e diverse leghe, al fine di ottenere risultati generali ed estendibili. La correttezza del metodo proposto è confermata dalla correlazione statistica dei parametri proposti con la resistenza meccanica statica, con la densità, la porosità, e da alcune significative analisi metallografiche (percentuale di ossidi sulle superfici di frattura, analisi dei difetti interni). Data l’efficacia dimostrata dei parametri proposti, ed in particolare di quelli legati al profilo di moto del pistone, l’approccio è stato esteso tramite lo sviluppo di alcune relazioni analitiche per calcolare i due parametri cinematici. Ciò rappresenta uno strumento efficace per sintetizzare a priori il profilo di moto ottimale del pistone che, nel rispetto dei vincoli di macchina, consenta di ottimizzare la qualità dei getti.
7
Binney, Matthew N. "Porosity reduction in high pressure die casting through the use of squeeze pins /." [St. Lucia, Qld.], 2006. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19810.pdf.
Full text
8
Tang, Caixian. "Soldering in magnesium high pressure die casting and its preservation by surface engineering." Swinburne Research Bank, 2007. http://hdl.handle.net/1959.3/22747.
Full textAbstract:
Thesis (PhD) - Swinburne University of Technology, Industrial Research Institute Swinburne - 2007.[A thesis submitted] for the degree of Doctor of Philosophy, Industrial Research Institute, Swinburne University of Technology - 2007. Typescript. Includes bibliographical references (p. 154-167).
9
Laukli, Hans Ivar. "High Pressure Die Casting of Aluminium and Magnesium Alloys : Grain Structure and Segregation Characteristics." Doctoral thesis, Norwegian University of Science and Technology, Department of Materials Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-379.
Full textAbstract:
Cold chamber high pressure die casting, (HPDC), is an important commercial process for the production of complex near net shape aluminium and magnesium alloy castings. The work presented in the thesis was aimed at investigating the microstructure formation in this type of casting. The solidification characteristics related to the process and the alloys control the formation of grains and defects. This again has a significant impact on the mechanical properties of the castings.
The investigations were carried out mainly using the AM60 magnesium alloy and the A356 aluminium alloy. Two different casting arrangements were used: the cold chamber HPDC and the gravity die casting methods, which allowed for different flow and solidification conditions. The microstructures in the castings were investigated using optical microscopy, image analysis, scanning electron microscopy, electron back scatter diffraction measurements and electron probe microanalysis.
In the HPDC experiments, the shot sleeve solidification conditions were investigated primarily by changing the melt superheat on pouring. This significantly affected the microstructures in the castings. The fraction of externally solidified crystals (ESCs) was consistently found to be largest near the gate in both the AM60 and the A356 die castings. This was attributed to the inherent shot sleeve solidification conditions and the flow set up by the plunger movement. When the superheat was increased, a lower fraction of ESCs was found in the castings. Furthermore, a high superheat gave ESCs with branched dendritic/elongated trunk morphology whilst a low superheat generated coarser and more globular ESCs, both in the AM60 and the A356 castings. The ESCs typically segregated towards the central region of the cross sections at further distances from the gate in the die castings.
When a thin layer of thermal insulating coating was applied on the shot sleeve wall in the production of AM60 die castings, it nearly removed all ESCs in the castings. Using an A356 alloy, (and no shot sleeve coating), with no Ti in solution gave a significantly lower fraction of ESCs, whereas AlTi5B1 grain refiner additions induced an increase in the fraction of ESCs and a significantly finer grain size in the castings. The formation of globular ESCs was enhanced when AlTi5B1 grain refiner was added to the A356 alloy.
In controlled laboratory gravity die casting experiments, typical HPDC microstructures were created by pouring semi-solid metal into a steel die: The ESCs were found to segregate/migrate to the central region during flow, until a maximum packing, (fraction of ESCs of ~35-40%), was reached. The extent of segregation is determined by the fraction of ESCs, and the die temperature affects the position of the ESCs. The segregation of ESCs was explained to occur during flow as a result of lift forces.
The formation of banded defects has also been studied: the position of the bands was affected by the die temperature and the fraction of ESCs. Based on the nature of the bands and their occurrence, a new theory on the formation of defect bands was proposed: During flow the solid distribution from the die wall consists of three regions: 1) a solid fraction gradient at the wall; 2) a low solid fraction region which carries (3) a network of ESCs. A critical fraction solid exists where the deformation rate exceeds the interdendritic flow rate. When the induced stress exceeds the network strength, deformation can occur by slip, followed by liquid flow. The liquid flow is caused by solidification shrinkage, hydrostatic pressure on the interior ESC network, and gaps forming which draw in liquid.
10
Fraser, Darren T. "Soldering in high pressure die casting and its prevention by lubricant and oxide layers /." [St. Lucia, Qld.], 2000. http://adt.library.uq.edu.au/public/adt-QU20010830.163828/.
Full text
11
Chintalapati, Pavan. "Solidification under pressure of aluminum castings." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2010r/chintalapati.pdf.
Full textAbstract:
Thesis (Ph. D)--University of Alabama at Birmingham, 2009.Title from PDF t.p. (viewed June 30, 2010). Additional advisors: Viola L. Acoff, Krishan K. Chawla, Raymond J. Donahue, Gregg M. Janowski, Harry E. Littleton (ad hoc). Includes bibliographical references (p. 143-138).
12
Gulizia, Stefan. "Soldering in high pressure die casting (HPDC) performance evaluation and characterisation of physical vapour deposition (PVD) coatings /." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/39640.
Full textAbstract:
Thesis (MEng) - School of Engineering and Science, Swinburne University of Technology, 2008.Thesis submitted for the degree of Master of Engineering, School of Engineering and Science, Swinburne University of Technology, 2008. Typescript. Includes bibliographical references (p. 98-101).
13
Watson, Douglas. "Microstructure and mechanical properties of ductile die-cast Al-Mg-Si-Mn alloys." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/12874.
Full textAbstract:
Aluminium alloys have been seen a dramatic increase in transport manufacturing in past two decades. This is primarily driven by the achievement of effective weight-savings, increased vehicle fuel efficiency and reduced CO2 emissions in transport. One of the significant progresses in most recent years has been in the application of aluminium-intensive car body structure, in which the manufacturing of thin wall castings with improved ductility is one of the critical issues. High pressure die casting (HPDC) is a fast and economical near-net shape manufacturing method to produce thin wall components. Therefore the application of HPDC process to make thin wall structural components for aluminium-intensive car body structure is one of the most challenges in recent development. However, the currently available die cast aluminium alloys are unable to fulfil this requirement because of the insufficient ductility, which is essential for joining castings with sheets and extruded parts. This has become critical in further development and extensive acceptance in car manufacturing industry. Generally, the mechanical properties of die castings are determined by alloy composition, defect levels and microstructure in the castings. In the present study, the significant achievement is the development of Al-Mg-Si-Mn alloy for HPDC process to provide improved ductility in die castings in order to satisfy the requirement of mechanical properties, in particular ductility for the application in automotive body structure. Starting from the thermodynamic analysis and CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) modelling of Al-Mg-Si system for solidification and phase formation, the alloy composition was optimised using international standard tensile samples to review the effect of various alloying elements on the mechanical properties. Another achievement is the understanding of the solidification and microstructural evolution, the relationship between the microstructure and mechanical properties, and the strengthening mechanisms in the developed alloy. The solidification behaviour in the shot sleeve and in the die cavity was examined for the formation of the primary α-Al phase, eutectic Al-Mg2Si phases in the alloy. The morphology, size and size distribution of the primary α-Al phase were characterised under different solidification conditions. The growth morphology of the primary α-Al phase formed in the shot sleeve and in the die cavity was analysed using the Mullins-Sekerka instability theory and the growth rate of eutectic Al-Mg2Si phases during solidification was calculated using Jackson-Hunt theory. Still another achievement is the study of the effect of Mn and Fe on the morphology, size and distribution of various Fe-rich compounds in the Al-Mg-Si alloy produced by HPDC process. The assessment was associated with the mechanical properties of yield strength, ultimate tensile strength and elongation with different Fe and Mn contents. CALPHAD modelling of multi-component Al-Mg-Si-Mn-Fe and Al-Mg-Si-Fe systems was studied to find out the effect of Fe impurity in the Al-Mg-Si alloy. The precise accumulation of iron during HPDC using fully recycled materials was examined to predict the maximum cycles to produce castings with required mechanical properties. The strengthening mechanism and the relationship between the microstructure and mechanical properties are explored in the alloy made by secondary materials. Furthermore, the effect of nickel on the microstructure and mechanical properties of the die-cast Al-Mg-Si-Mn alloy was also studied in association with the formation of Ni-rich intermetallics during solidification in the die-cast Al-Mg-Si-Mn alloy containing different Ni contents. The final achievement is the understanding of the repeatability of die castings made by the new alloy with industrial scale components. The tensile properties of standard samples that were obtained directly from HPDC process and made by the machined die castings at different locations were further assessed for the reproducibility of casting components made by the Al-Mg-Si-Mn alloy. The distributions of yield strength, ultimate tensile strength and elongation of the tensile samples were analysed by the average values with standard deviations and by the Weibull statistical model with three parameters. The correlations between the mechanical properties and the microstructural features, porosity levels and fracture morphology were investigated for the different types of samples. It was found that three-parameter Weibull analysis was capable of analysing the reproducibility of die cast components and the scattering of tensile properties was mainly due to the presence of porosity and non-uniform microstructure in the die-castings.
14
Newell, Matthew David. "Aspects of a novel casting process for the production of nickel-based superalloy high pressure turbine blades." Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/525/.
Full textAbstract:
A novel process in which individual turbine blades are produced by the high rate solidification method has been developed. The technology, with an optimised radiation baffle, gave a thermal gradient of 11.64 x 10\( 3\) K.m\( {-1}\), whilst maintaining a flat solidification front, calculated using a specially created and validated process model. The corresponding primary dendrite arm spacing was reduced to 165 x 10\( {-6}\) m and the calculated freckle potential was below the critical threshold limit identified by Beckermann et al. (2000), even in highly freckle prone alloys. Low angle grain boundaries formed when misorientation accumulates in growing dendrite envelopes which subsequently converge were studied experimentally. While extensive dendrite branching or steady state growth was found to lead to an average primary dendrite misorientation of 2.3 ° that was random in nature, enhanced growth kinetics accompanying non steady state growth, found in platforms, produced a monotonic increase in accumulated misorientation of up to 10 °. It was concluded that the latter is due to mechanical moments arising from extensive growth of unsupported tertiary dendrite branches growing laterally across the platform normal to the direction of gravity. The degree of misorientation is therefore dependent on local geometry and mushy zone shape.
15
Roberts, Michael John, and edu au jillj@deakin edu au mikewood@deakin edu au wildol@deakin edu au kimg@deakin. "A Modified Life Cycle Inventory of Aluminium Die Casting." Deakin University. School of Engineering and Technology, 2003. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20040825.110759.
Full textAbstract:
Aluminium die casting is a process used to transform molten aluminium material into automotive gearbox housings, wheels and electronic components, among many other uses. It is used because it is a very efficient method of achieving near net shape with the required mechanical properties. Life Cycle Assessment (LCA) is a technique used to determine the environmental impacts of a product or process. The Life Cycle Inventory (LCI) is the initial phase of an LCA and describes which emissions will occur and which raw materials are used during the life of a product or during a process. This study has improved the LCI technique by adding in manufacturing and other costs to the ISO standardised methods. Although this is not new, the novel application and allocation methods have been developed independently. The improved technique has then been applied to Aluminium High Pressure Die Casting. In applying the improved LCI to this process, the cost in monetary terms and environmental emissions have been determined for a particular component manufactured by this process. A model has been developed in association with an industry partner so this technique can be repeatedly applied and used in the prediction of costs and emissions. This has been tested with two different products. Following this, specialised LCA software modelling of the aluminium high pressure die casting process was conducted. The variations in the process have shown that each particular component will have different costs and emissions and it is not possible to generalise the process by modelling only one component. This study has concentrated on one process within die casting but the techniques developed can be used across any variations in the die casting process.
16
Pereira, Manuel Filipe Viana Teotonio. "ADDITIVE MANUFACTURING OF COMPONENTS FOR IN-DIE CAVITY USE, SUITABLE TO WITHSTAND ALUMINIUM HIGH PRESSURE DIE CASTING (HPDC) PROCESS CONDITIONS." Thesis, Bloemfontein: Central University of Technology, Free State, 2013. http://hdl.handle.net/11462/243.
Full textAbstract:
Thesis (M. Tech. (Engineering: Mechanical)) -- Central University of Technology, Free State, 2013This research examines the suitability of Additive Manufacturing (AM) for manufacturing dies used in aluminium high pressure die casting. The study was guided by the following objectives: • The reviews of applicable literature sources that outline technical and application aspects of AM in plastic injection moulds and the possibilities of applying it to high pressure casting die. • To introduce AM grown die components in die manufacture. Further, to develop a methodology that will allow industry to apply AM technology to die manufacture. • Revolutionise the way die manufacture is done. The potential for AM technologies is to deliver faster die manufacture turnaround time by requiring a drastically reduced amount of high level machining accuracy. It also reduces the number of complex mechanical material removal operations. Fewer critical steps required by suitable AM technology platforms able to grow fully dense metal components on die casting tools able to produce production runs. • Furthermore, promising competitive advantages are anticipated on savings to be attained on the casting processing side. AM technology allows incorporation of features in a die cavity not possible to machine with current machining approaches and technology. One such example is conformal cooling or heating of die cavities. This approach was successfully used in plastic injection mould cavities resulting in savings on both the part quality as well as the reduction on cycle time required to produce it (LaserCUSING®, 2007). AM technology has evolved to a point where as a medium for fast creation of an object, it has surpassed traditional manufacturing processes allowing for rapidly bridging the gap between ideas to part in hand. The suitability of the AM approach in accelerating the die manufacturing process sometime in the near future cannot be dismissed or ignored. The research showed that there is promise for application of the technology in the not too distant future. In the South African context, the current number and affordability of suitable AM platforms is one of the main stumbling blocks in effecting more widespread applied research aimed at introduction of the technology to die manufacture.
17
Watson, Robert. "New numerical techniques to quantify and predict the effect of entrainment defects, applied to high pressure die casting." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7153/.
Full textAbstract:
High Pressure Die Casting (HPDC) is an attractive option for automotive manufacturers, as it has a number of advantages over wrought process routes. An improved understanding of the defects which may result from the process could allow castings to deliver lighter vehicle structures. A novel algorithm was developed to predict the formation of entrainment defects, which may limit the strength of castings. This model was integrated into FLOW-3D, a fluid dynamics solver. Theoretical advances were made, which offer a means of extrapolating a spatial distribution of damage to location specific statistical distributions, an improved way of characterising the contribution of each defect type to strength, and a means of correlating parameters for statistical distributions, allowing the variation in strength may be predicted at arbitrary locations within a casting. Casting and numerical experiments were performed, to evaluate these algorithms and underlying fluid flow solution, and to test the influence of entrainment defects on the strength of HPDC parts. Defects formed by air entrainment were found to significantly limit the strength of the studied castings. The methods and techniques explored in this work showed promise, but further advances would be needed, before ab intio strength prediction for HPDC parts can be realised.
18
Pereira, M. F. V. T., M. Williams, and Preez W. B. Du. "Characterization of metal powder based rapid prototyping components with respect to aluminium high pressure die casting process conditions." Journal for New Generation Sciences, Vol 8, Issue 2: Central University of Technology, Free State, Bloemfontein, 2010. http://hdl.handle.net/11462/563.
Full textAbstract:
Published ArticleThis paper is based on tests performed on die component specimens manufactured by EOS-DMLS (direct metal laser sintering) and LENS (laser engineered net shape) RP (rapid prototyping) technology platforms, as well as manufactured specimens machined out of preferred standard hot work steel DIN 1.2344. These specimens resemble typical components used in metal high pressure die casting tool sets. The specimens were subjected to a programme of cyclic immersion in molten aluminium alloy and cooling in water-based die release medium. The heat checking and soldering phenomena were analyzed through periodic inspections, monitoring crack formation and evidence of surface washout. At the end of the thermal tests, mechanical strength and hardness tests were performed to assess toughness and core resistance variations in relation to the initial conditions. Finally metallographic investigations were performed through optical microscopy on all the specimens considered. The outcomes of this research will be presented and used by the CSIR for further development and application of the assessed EOS-DMLS and LENS rapid prototyping technologies in rapid die manufacturing techniques and die design principles, including time and economic feasibility criteria to be applied when considering rapid die manufacture.
19
Pereira, M. F. V. T., M. Williams, and R. Bruwer. "Rapid die manufacturing using direct laser metal deposition." Journal for New Generation Sciences, Vol 7, Issue 3: Central University of Technology, Free State, Bloemfontein, 2009. http://hdl.handle.net/11462/542.
Full textAbstract:
Published ArticleGlobal issues such as energy and climate changes have impacted on both the automotive and aerospace industries, forcing them to adopt measures to produce products that consume fewer combustibles and emit less carbon dioxide. Making vehicles lighter is one of the logical ways of reducing fuel consumption. The need for light components, able to fulfil technical and quality specifications, led to market growth for tooling that is able to mass produce parts using manufacturing processes such as high pressure die casting. Competitive pressures to reduce the lead time required for tooling-up has also increased dramatically. For this reason research into various methods, techniques and approaches to tool manufacture is being undertaken globally. This paper highlights the work undertaken at the CSIR on the issue of rapid die manufacturing through the application and evaluation of a rapid prototyping technique and coating technologies applied to die components of a high pressure casting die for the production of aluminium components. Criteria for determining suitability were developed against which the technique was evaluated that included time, cost and life-expectancy. Results of accelerated testing procedures to evaluate the die material produced by the rapid prototyping technique and surface coatings and treatments of die materials for their resistance to washout, erosion, heat checking and corrosion in a high pressure die casting environment, are presented. The outcomes of this research will be used for further development and application of specific techniques, design principles and criteria for this approach.
20
Okcu, Isik Yilmaz. "Effect Of Process Parameters On Mechanical Properties Of High Pressure Die Cast Magnesium Az91 Components." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613896/index.pdf.
Full textAbstract:
Before beginning the experimental work of this study, a magnesium high pressure die casting facility is set up to manufacture magnesium cast parts for defence industry. In this thesis two components are cold chamber high pressure die casted using magnesium alloy AZ91 as raw material, and one component was manufactured using both aluminium alloy A.413, and magnesium alloy AZ91.
Mechanical properties of high pressure die casting parts depend on various parameters such as, thickness of the cast part, position of the cast part in the cavity, molten metal temperature, die temperature, piston speeds, and injection pressure. The aim of this study is to investigate the effects of section thickness of the cast part, position of the cast part in the die cavity, piston speeds, and molten metal temperature on mechanical properties of magnesium die cast parts. Tensile properties of products from Al A.413 and Mg AZ91 alloys are also compared.
Casting analysis software is used to simulate filling and temperature evolution of three different casting components. Piston speeds are first calculated from equations in the literature and then verified by using the software. Specimens for microstructural investigation, and mechanical tests are machined directly from the mass produced parts. Optical microscopy, and scanning electron microscopy investigations are carried out for grain size and porosity determination. Tensile tests are conducted for yield strength, ultimate tensile strength, and % elongation values. The results of casting analysis software simulations, grains size investigations, porosity investigations, and tensile tests are correlated to each other.
Optimum piston speeds, optimum molten metal temperatures are observed, effect of grain size and porosity concentrations on the effect of mechanical properties are compared. Weight of cast parts produced from Mg AZ91 are 35 % lower than that of Al A.413 parts. However, ultimate tensile strength of the cast parts produced from Mg AZ91 are found to be similar to the aluminium parts.
21
Battaglia, Eleonora. "Correlations between defect content, microstructure and casting quality in HPDC AlSi alloys." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3427147.
Full textAbstract:
Two are the key players of this doctoral thesis: secondary AlSi alloys and the High Pressure Die Casting (HPDC) process.
As the levels of CO2 and other greenhouse gasses increase, the industry sector is called to reduce the emissions produced and to contain the energy consumptions. Therefore, secondary Al ingot production shows a 6% annual rate growth, mainly drawn by the transport sector.
In particular, automotive industry and, in general, transportation one increasingly needs light components in order to reduce total weights and therefore limit harmful emissions and fuel consumption. To this end, HPDC process is getting more and more crucial. It is, on one hand, versatile and highly productive but, on the other, the elevated amount of defects found in the castings sometimes compromises the characteristics of the final product.
The research activities performed during the Ph.D. years focused on the High Pressure Die Casting (HPDC) process and the assessment of the correlations between process parameters, casting quality and mechanical response improvement. The research work comprises three interconnected topics: (i) the effect of the process on the casting quality in terms of defect generation and eutectic Si morphology, (ii) how defects and microstructure influence the mechanical response of the components and (iii) how the mechanical properties can be improved through specific heat treatments.
The thesis starts dealing with the work developed within the EU MUSIC project aimed at transforming a production-rate-dominated manufacturing process into a quality/efficiency-driven and integration-oriented one. In the frame of the EU MUSIC project, an investigation procedure was developed which led to the definition of preliminary correlations between process parameters, defect content and static mechanical properties obtained analyzing both reference castings and commercialized industrial demonstrators.
A specific focus was always devoted to the possible industrial application in order to narrow down the gap between academic research and industry.
The second section deals with the definition of a so-called Penalty Index based on FE simulation model and fractographic investigations. It gave satisfactory predictions of both static strength and fatigue life of castings based on defect locations on the fracture surfaces and their projected areas. The elaborated criterion gives good results even though it does not take into account the real morphology of defects (which can be a very complex 3D morphology in the case of irregular flaws); its main drawback is that it is a "post-mortem" application. However, this limit can be overcome thanks to the wider diffusion of industrial high-resolution Computed Tomography (CT).
The third section is mainly dedicated to the study of HPDC microstructure. Two secondary Al-Si alloys, an AlSi12(b) and an AlSi12Cu1(Fe), were used to produce HPDCs. In both cases, there was an evident non-homogeneity of the microstructure, in particular of the eutectic Si morphology which could be correlated, to some extent, to the different as-cast mechanical response of the castings. Heat treatments at 350°C and soaking times ranging from1 to 8 hours were performed
Mechanical testing, hardness and metallographic investigations were carried out in order to understand the effect of the heat treatments. Microstructural observations using OM, SEM, TEM and EBSD investigations were also performed.
Based on the obtained results, the heat treating procedure was effective since it did not cause surface blistering (a real issue in the heat treatment of die castings) or component distortion.
The visible mechanical improvement in terms of both static and fatigue response was determined by Si crystals’ size and morphology. Thanks to heat treatment, the Si particle morphology changed from an interconnected ‘network’ to a more fragmented and smooth one. In terms of mechanical behavior, from a rapid crack propagation which led to a drastic reduction of the load-bearing area during the component use, the heat treatment caused a less instantaneous failure since the crack had to propagate through the ductile Al matrix.
The best solution was assessed and proposed to obtain significant mechanical properties and low costs.
Preliminary lab tests aimed at verifying the effect on the eutectic Si of common alloying elements such as Cu and Fe were finally conducted. A small mold was designed and manufactured in order to produce castings with solidification velocities comparable with those typical of the HPDC process. The base alloy was an AlSi12(b) ingot which was melt and several elements (i.e. Cu, Fe, Mn) were added to reach the AlSi12Cu1(Fe) alloy ranges. A refining effect of Cu was observed, however further investigations are necessary in order to better understand its joined effect with Fe.
This doctoral thesis deals with a complex topic; a high number of sequential actions are involved in the process. This is the reason why the developed work brought interesting and useful results, but it can also be considered a starting point for further investigations. Further analyses can be conducted to understand the causes of the non-uniform eutectic Si morphology and the nature of the Si precipitates within the α-Al phase as well as an enhancement of the elaborated Penalty Index can be obtained.In questa tesi di dottorato vengono presi in considerazione due principali aspetti: le leghe AlSi secondarie e il processo di pressocolata (HPDC). Poiché i livelli di CO2 e gas serra sono in continuo aumento, il settore industriale è chiamato a ridurre le emissioni prodotte e contenere i consumi energetici. Perciò la produzione di Alluminio secondario mostra un aumento annuale del 6%, trainato principalmente dal settore dei trasporti. In particolare, l'industria automotive e, in generale, quella dei trasporti necessitano sempre più di componenti leggeri al fine di ridurre i pesi totali e di conseguenza limitare le emissioni dannose ed il consumo di carburante. A questo fine, il processo di pressocolata sta diventando sempre più cruciale. Esso, da un lato, è versatile e altamente produttivo, ma dall'altro l'elevata quantità di difetti che si possono trovare nei getti talvolta compromette le caratteristiche finali dei getti. L'attività di ricerca condotta durante gli anni di dottorato si è focalizzata sul processo di pressocolata e la valutazione delle correlazioni tra parametri di processo, qualità dei getti e miglioramento della risposta meccanica. Il lavoro di ricerca comprende tre argomenti interconnessi: (i) l'effetto del processo sulla qualità dei getti in termini di generazione di difetti e morfologia del Silicio, (ii) come difetti e microstruttura influenzano la risposta meccanica dei componenti e (iii) come le proprietà meccaniche possono essere migliorate attraverso specifici trattamenti termici. La tesi inizia riportando il lavoro svolto nell'ambito del progetto ricerca Europeo MUSIC finalizzato a trasformare un processo dominato dal livello produttivo in uno guidato da qualità, efficienza ed integrazione. Nel contesto del progetto MUSIC, è stata sviluppata una procedura di indagine in grado di portare alla definizione di alcune correlazioni preliminari tra parametri di processo, contenuto difettologico e proprietà meccaniche statiche ottenute analizzando sia getti di riferimento sia dimostratori industriali già in produzione. E' stato dedicato un focus particolare alle possibili applicazioni industriali al fine di restringere il divario tra ricerca accademica e industria. Nella seconda sezioni si procede alla definizione di un così detto Indice di Penalità basato sulla simulazione FEM e l'analisi frattografica. Esso ha dato correlazioni significative sia con le proprietà meccaniche statiche che a fatica dei getti basandosi sulla posizione dei difetti sulla superficie di frattura e le relative aree proiettate. Il criterio elaborato fornisce buoni risultati anche se non consente di prendere in considerazione la reale morfologia dei difetti (che può essere molto complessa nel caso di difetti irregolari); il principale svantaggio del criterio è il fatto che si tratti di un'applicazione "post-mortem". Tuttavia, il limite potrà essere superato grazie alla vasta diffusione della Tomografia Computerizzata industriale. La terza sezione della tesi è dedicata principalmente allo studio della microstruttura di getti pressocolati. Sono state utilizzate due leghe secondarie, AlSi12(b) e AlSi12Cu1(Fe), per la produzione dei getti. In entrambi i casi si è riscontrata una notevole disomogeneità della microstruttura, in particolare della morfologia del Si correlabile, in parte, alle differenti risposte meccaniche dei getti allo stato as-cast. Sono stati quindi condotti trattamenti termici a 350°C per tempi variabili dall'1 alle 8 ore. Sono state quindi condotte prove meccaniche, di durezza e analisi metallografiche al fine di capire l'effetto dei trattamenti termici. Si sono svolte analisi microstrutturali tramite microscopio ottico, SEM, TEM e EBSD. Sulla base dei risultati ottenuti, la procedura di trattamento termico è stata valutata efficace dal momento che, in primo luogo, non si sono causati blister sulla superficie dei getti o distorsione dei getti. L'evidente miglioramento meccanico sia statico che a fatica è stato determinato dalla dimensione e morfologia dei cristalli di Silicio. A seguito del trattamento termico, si è verificata una modifica del delle particelle di Si e il passaggio da una morfologia interconnessa ad una più frammentata e arrotondata. In termini di risposta meccanica, da una propagazione rapida che porta ad un cedimento drastico dell'area resistente del componente, si è passati ad una rottura meno istantanea per effetto della propagazione della cricca attraverso la matrice duttile di Alluminio. E' stata valutata e proposta la soluzione migliore in grado di fornire un buon compromesso tra risposta meccanica e costi contenuti. Sono stati quindi condotti esperimenti preliminari in laboratorio al fine di verificare l'effetto sul Si eutettico di alliganti comuni quali Cu e Fe. Tramite la costruzione di un piccolo stampo in grado di fornire velocità di raffreddamento comparabili a quelle della pressocolata si sono condotti studi sulle due leghe sopracitate. Si è osservato un effetto affinante dovuto al Cu, tuttavia ulteriori analisi sono necessarie per approfondire l'effetto del Fe. La tesi riguarda perciò una tematica complessa; nel processo di pressocolata sono richieste un numero elevato di azioni consecutive. Questo è il motivo per cui la ricerca condotta ha portato risultati interessati e utili, ma deve allo stesso tempo essere considerata un punto di partenza per ulteriori approfondimenti. Saranno necessarie nel futuro ulteriori analisi ed indagini.
22
Štipl, Pavel. "Technologie lití vysokotlakých odlitků a vlivy působící na jejich kvalitu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231432.
Full textAbstract:
This diploma thesis deals with the technology of high pressure die casting and especially influences having effect on their final quality. The aim of this thesis is to design the measures to convert casting of the cylinder for chainsaw into the serial production. The thesis contains a description of the production of castings by technology of high pressure die casting, theoretical analysis of the factors with effects on their final quality and practical description of the conversion casting of cylinder for chainsaw into the serial production. The problem of converting to serial production has been solved by several samplings and final test series. Part of each sampling is analysis of defects and design of measures leading to elimination or at least minimization of such defects. On the basis of the production process has been successfully optimized and casting of the cylinder for chainsaw was successfully converted into the serial production. The results of this work also allowed for a smooth conversion into the serial production of another type of cylinder, manufactured by company MOTOR JIKOV.
23
Klarner, Andrew Daniel. "Development of Mg-Al-Sn and Mg-Al-Sn-Si Alloys and Optimization of Super Vacuum Die Casting Process for Lightweight Applications." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515083355012541.
Full text
24
Dočekal, Václav. "Vady tlakově litých odlitků ze slitin hliníku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401515.
Full textAbstract:
This thesis is focused on defects occurring in products made by high pressure die casting of aluminum alloys. The theoretical part includes introduction to high pressure die casting technology and description of individual defects, causes and corrective procurations. The practical part focuses on the determination of the defect on the pre-selected casting, which is cast in the foundry ALW INDUSTRY, s.r.o. Based on the identification of the defect, there is a corrective procuration to reduce its occurrence.
25
Míšek, Jakub. "Vliv odplynění na kvalitu odlitků vyrobených technologií vysokotlakého lití." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318844.
Full textAbstract:
This thesis examines the influence of the degassing process on hydrogen contend and on the quality of part casted by high pressure casting technologies. The type of defects occurring in the casting is analyzed based on macrostructure and microstructure observations. For the overall assessment is used the statistical observation of the evolution trend of scrapping during the experiment. The results show that shortening of the degassing time may affect the incidence of porosity defect.
26
Svoboda, Rostislav. "Tlakově lité odlitky z Mg slitin - trendy vývoje." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228049.
Full textAbstract:
The aim of this thesis is to determine influence of porosity and shape-factor over mechanical properties, performed on cast samples from Aalen foundry (Germany), that were high pressure die casted from AZ91 D Alloy. Evaluation of these quantities was done using computer software Olympus Five. Measured values were subjected to statistical analysis in order to eliminate gross errors and determine linear dependence between mechanical properties and porosity eventually voids shape factor.
27
Jankes, Erik. "Využití řízeného naplyňování slitin Al-Si při tlakovém lití." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231052.
Full textAbstract:
This master thesis will cover the possibility of using directed gassing of Al-Si alloys in a high pressure die casting foundry. As a control gas, rotary degasser with gaseous 20 % H2 in N2 as a medium was used. Castings were casted via high pressure die casting machine. The aim of this research is to compare internal defect such as porosity or shrinkage of a casts made from degassed and control gassed melt.
28
Outmani, Imane. "Caractérisation des variabilités Matériaux/ Process pour une convergence produit de fonderie par approche prédictive." Thesis, Paris, ENSAM, 2017. http://www.theses.fr/2017ENAM0007/document.
Full textAbstract:
Les alliages Al-Si sont largement utilisés dans l’industrie automobile en fonderie sous pression, en particulier pour la fabrication des blocs moteurs, en raison de leurs bon rapport résistance/ poids et leurs excellentes propriétés mécaniques. Du fait de l’internationalisation de la production, la composition chimique de ces alliages et les paramètres du procédé HPDC peuvent varier d’un pays à l’autre, ils peuvent même varier d’un site de fabrication à l’autre dans le même pays. Or, les conceptions des pièces automobiles sont aujourd’hui de type déterministe et elles sont réalisées sur la base des matériaux et procédés européens, ce qui peut affecter les propriétés de ces pièces dans le cas d’une localisation hors Europe. Ainsi, il est important de pouvoir adapter les conceptions rapidement et à moindre coût en prenant en compte les contraintes matériau/ process locales. Dans cette thèse, nous avons proposé une approche méthodologique permettant de prédire les caractéristiques mécaniques en fonction de la variabilité matériaux/ process en s'appuyant sur une étude expérimentale/ statistique de l’effet de la variabilité des principaux éléments d’alliage (Si, Cu, Mg) et des paramètres procédé (température de la coulée et pression d’injection) sur les propriétés mécaniques des alliages d’Al-Si moulés sous pression. La microstructure et le taux de porosités ont également été évalués. Cette méthodologie a abouti à la construction d’un outil de conception produit permettant de prédire les caractéristiques mécaniques dans le cas du changement de l’un (ou des) paramètres Matériau/ ProcessSecondary Al-Si alloys are widely used in automotive industry for engine blocks because they offer a considerable weight reduction whilst maintaining good mechanical properties. The ever-expanding internationalisation of production, with same stages of production processes spread across a number of countries to produce locally, causes however high variability in the casting products. The chemical composition of the same alloys and the working variables of the unchanged high-pressure die casting process (HPDC) may change for the same casting parts from one country to another, they can even sometimes vary from one manufacturing site to another within the same country. Designing for aluminium automotive components does call today for new deterministic design methods that are often achieved from European material and casting process databases, which can affect the properties of these parts in the case of a location outside Europe. Thus, it is important to adapt the design of die casting parts quickly and inexpensively by taking into account the material and process local constraints. In this work, a methodological approach which permits to predict mechanical properties as a function of material and process variability based on an experimental/ statistical study on the effect of the variability of the primary factors of alloying elements contents (Si, Cu and Mg) and HPDC process parameters (casting temperature and injection pressure) on mechanical properties of die cast aluminium alloys has been proposed. The microstructural features and the porosity level were also investigated and assessed. This approach has resulted in statistical design tool that will allow designers to make changes to the design of their casting and to industrialize them outside Europe
29
Tharayil, Pradeep Ambareeksh, and Mohammadali Baradaran. "HPDC Die design for Additive Manufacturing : Simulation and Comparison of Thermal Stresses in HPDC die designed for Additive Manufacture." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Industriell produktutveckling, produktion och design, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-43319.
Full textAbstract:
Additive manufacturing has a great potential to benefit die manufacture by shortening the lead time considerably and lifting the limitations on design complexity imposed by conventional manufacturing techniques. However, AM has its own requirements that together are known as Design for Additive Manufacturing and account for the process limitations. One of the significant requirements is mass efficiency of the design (it should be as light as possible). If it’s not fulfilled, AM won’t be able to make an economical solution or substitution despite having outstanding benefits. The present investigation has been framed with respect to such concern. This investigation attempts to draw a comparison between the performance of two design variants. Additionally, it has been tried to study the employed method, document implementation of the approach, and identify the challenges in accordance with design for additive manufacturing. Simulation of thermal stresses generated in die inserts for a given component during one cycle of high pressure die casting is presented. Initial design of the die inserts is subjected to redesign with the intention of mass reduction by incorporating honeycomb structure. Temperature evolution and resultant thermal stresses are analyzed for redesign and compared to those of original design. Simulation of high pressure die casting was carried out in MagmaSoft to obtain temperature history of die inserts and cast. Implicit nonlinear elastic fully coupled thermal displacement model was setup in Abaqus in which Magma results were used as input for stress calculation. Results show that according to our specific design, HPDC die with thin walled feature cannot withstand the thermal and mechanical load. However, with iterative analysis and proper topology optimization, a lightweight complex geometry die can be successfully made.
30
Knoll, Octavian [Verfasser], Karl [Mitwirkender] Schweizerhof, and O. S. [Akademischer Betreuer] Hoppenstad. "A Probabilistic Approach in Failure Modelling of Aluminium High Pressure Die-Castings / Octavian Knoll. Betreuer: Karl Schweizerhof ; O. S. Hoppenstad." Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1081213019/34.
Full text
31
Kolda, Vlastimil. "Numerická simulace plnění a tuhnutí odlitku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228294.
Full textAbstract:
The object of this diploma thesis is to analyze, persuant to numerical simulation of current technology of production aluminous casting roller-reck V9X, causes of the rise of cold lap and laminations defects. Consequently, to work up a project of variant solution of the shape of casting so, as to come to elimination mentioned defects. This variant solving will be tested with numerical simulation as well. Fruitfulness of these designed changes will be verified by testing molten of the casting. In terms of solve the problem the simulation of cycling of the mold and subsequently the filling of the casting will be effected. During the analyse of filling of the die the first phase of filling will be effected too.It means the movement of the piston throught the chambre. Simulation of solidification of the casting wont be effected because of the type of the defect.
32
Afsaridis, Kimon. "Investigation of residual stresses generation in aluminum flywheel." Thesis, Jönköping University, Jönköping University, JTH. Research area Product Development, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-9255.
Full textAbstract:
Quality of the castings is affected by several factors which the designer should take into consideration during the product development process. Although residual stress is one of those, it is often not considered in practical computations. Hence residual stresses are one of the forgotten areas in designing of machine parts. This master thesis is focused on the investigation of residual stresses in a high pressure die casted component, with the aim of extending its service life, by taking results from the study as a feedback.
The investigation of residual stresses was done on a variety of specimens, cast aluminum flywheel, provided by Husqvarna AB. This flywheel is a component in a product of the same company.In evaluating the residual stresses in the part, two tools-simulation and physical measurement were used. Moreover, comparison with these two methods is also done at an area of interest on the flywheel. The simulation was carried out by using MAGMAhpdc-a module for high pressure die casting process, from the commercial software package MAGMAsoft; while for the physical measurements, the hole drilling method was used, a method believed to be less accurate at low stresses areas.
The findings obtained from this study show that the results from both procedures are close, with small deviations observed, which reveals the reliability of the hole drilling method even when the stress levels are low. It is also found that the compressive residual stresses dominate in the component-a preferred phenomenon with regards to residual stress.
33
Schremmer, Michael. "Potentialanalyse zur Verwendung des Leichtmetalls Magnesium im Fahrwerk eines Automobils." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-118583.
Full textAbstract:
Im Rahmen der Arbeit wurde das Potential von Magnesium für den Einsatz im Fahrwerk eines Automobils, am Beispiel der Querbrücke des Hinterachsträgers, ermittelt. Verschiedene Mg-Legierungen wurden im konventionellen und vakuumunterstützen Druckguss vergossen und der Al-Legierung vergleichend gegenübergestellt. Es wurden in einem ersten Schritt statische und zyklische Werkstoffkennwerte sowie Materialmodelle erforscht und bewertet. Verschiedene Lastfälle im Standard- und Sonderfahrbetrieb wurden durch statische und zyklische Betriebsfestigkeitssimulationen abgesichert. Konstruktive Bauteiloptimierungen waren notwendig um den Werkstoff Magnesium an die Anforderungen der Querbrücke anzupassen. Äußere Umwelteinflüsse im Fahrbetrieb machten ein Korrosionsschutzkonzept für die Querbrücke aus Magnesium notwendig. Untersucht wurden dabei verschiedene Maßnahmen zur Vermeidung von Kontakt- und Oberflächenkorrosion. Grundsätzlich scheint der Einsatz von Magnesium im Fahrwerk im Bereich mittlerer Betriebsbelastungen denkbar.
34
Blombäck, Oscar, and Marcus Dahlén. "Minimering av porositet vid vakuumassisterad kallkammarpressgjutning av Al-Si : En fallstudie enligt DMAIC på Husqvarna Group." Thesis, Luleå tekniska universitet, Institutionen för ekonomi, teknik, konst och samhälle, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85097.
Full textAbstract:
Pressgjutna Al-Si komponenter förekommer mer och mer i förbränningsmotorer med syfte att reducera vikt och förbättra hållbarhet. Ett problem vid pressgjutning, en process kännetecknad av kostnadseffektivitet vid massproduktion, är porositetsbildning vilket kan resultera i läckage, strukturell svaghet och försämrad hållbarhet och livslängd för tillverkade komponenter. Då porer oftast bildas internt försvåras dessutom identifiering av potentiellt trasiga komponenter. Det är därför av vikt att finna parameterinställningar i pressgjutningsprocessen vilka konsekvent minimerar porositetsbildning. Ett företag som drabbas av återkommande porositets-relaterade defekter är Husqvarna Group. De använder vakuumassisterad pressgjutning för att, bland annat, producera motorcylindrar av Al-Si. Kassationsgraden, specifikt hänförbar till porositet, för en cylindermodell har under de senaste tre åren fördubblats vilket har resulterat i slöseri av produktionstid och kvalitetsbristkostnader. Vakuumassisterad pressgjutning kan beskrivas stegvis: (1) smält metall hälls i en cylindrisk fyllkammare, (2) en skottkolv trycker smältan mot ett mindre inlopp i låg hastighet för att undvika turbulens, samtidigt som vakuum ansätts i fyllkammare och gjutverktyg, (3) skottkolvshastigheten ökar markant vid en förinställd omslagspunkt, vilket spray-fyller gjutverktyget, och (4) högt tryck ansätts för att eftermata smälta till gjutverktyget när solidifiering sker. Syftet med detta examensarbete har varit att undersöka om och hur diverse parametrar, hänförbara till de nämnda processtegen, påverkar porositetsbildning i en industriell produkt. Därefter applicerades den erhållna processförståelsen för att identifera parametrar kritiska för porositetsbildning och slutligen rekommendera parameterinställningar som konsekvent minimerar porositetsgraden. Det experimentella upplägget bestod av två steg varav det första ämnade undersöka, via simulering, vilka av 6 parametrar som påverkade porositetsgraden utifrån en reducerad tvånivåers försöksdesign. Det andra steget var ett verkligt experiment i produktionsmiljö där de tre identiferade parametrarna från screening-experimentet varierades enligt en central-composite design. Analysen av experimenten resulterade i parameterinställningar som förväntas reducera porositetsgraden med över 70%. En lägre porositetsgrad kommer troligen reducera kassationsgraden av den undersökta cylindermodellen, vilket hade resulterat i finansiell besparing och effektivare produktion. I ett industriellt kontext bidrar detta exjobb huvudsakligen med en systematisk kvalitetsförbättrande metod för pressgjutna komponenter baserad i såväl simulerad som verklig miljö.Pressure die casted Al-Si components are increasingly found inside internal combustion engines, resulting in weight reduction and increased durability. Characteristic to die casting, commonly associated with cost-effective mass production, is the formation of pores which, if unnoticed, can cause leakage, structural deficiencies, and thus reduced durability and life-length of components. Pores commonly appear internally, making identification of faulty components difficult. Therefore, finding parameter settings in the die casting process that consistently minimizes the formation of pores is of importance. A company struggling with porosity-related defects is Husqvarna Group, currently using vacuum-assisted die casting to produce engine cylinders of Al-Si. Scrap-rate, specifically related to porosity, of a particular cylinder model has doubled in the last three years, causing waste of both precious production time and higher quality deficiency costs. A vacuum-assisted die casting process consists of several steps: (1) liquid Al-Si is poured into a cylindrical shot sleeve, (2) a plunger is moved towards a small gate, leading to the die cavity, at low velocity as to not cause turbulence, whilst vacuum is applied throughout the cavity and shot sleeve, (3) plunger velocity is increased substantially at a predetermined switch point, resulting in a spray-filling of the die cavity, and (4) high pressure is applied to continue the feed of molten metal into the cavity as solidification occurs. The purpose of the thesis has been to investigate if and how various parameters, related to the aforementioned four steps of the die casting process, impact the porosity amount in an industrial product. The acquired process knowledge was then applied to identify parameters affecting porosity and recommend settings that consistently minimize the porosity amount. The experimental procedure consisted of two steps: firstly, a screening experiment of six process parameters was made by simulating the die casting process according to a fractional factorial design. Secondly, a real-world experiment was conducted following a central-composite design by varying the three most impactful parameters from the screening experiment. Analysis of the experiments resulted in a selection of parameter settings, anticipated to reduce porosity by over 70%. A lower porosity amount will most likely reduce the scrap rate of the cylinder model, resulting in substantial savings and higher production efficiency. For practitioners, the main contribution of this thesis is a method of systematic quality-improvement to die-casted components by a combination of simulation experiments and real-world tests.
35
Timelli, Giulio. "Correlation between processing and quality of aluminium alloy castings (Correlazione tra parametri di processo di fonderia e qualità dei prodotti)." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425051.
Full textAbstract:
The influence of processing and process parameters plays a key role for the Aluminium foundry and transport industries as it affects the quality and soundness of the cast products. Particularly, the choice of a process chain in Aluminium foundry, otherwise of process parameters, influences the reject rates, hence casting costs, the process yield and the production rate. The process chain in Aluminium foundry is a complex sequence of processes and the final casting quality depends on many parameters. Several aspects of this subject are still not fully understood. The motivation of the research presented in this doctoral thesis work was, therefore, to fill this gap in knowledge. The study has aimed at understanding the influence of various process and process parameters of foundry on the quality of aluminium alloy castings and, in particular, Al-Si based castings.
A literature review and a sufficient background of previously reported results on the influence of processing and process parameters on the quality of aluminium alloy castings, physical fundamentals as well as industrial challenges, motivation and goals were carried out.
Special attention in Aluminium process chain has been given to:
The modification of aluminium-silicon cast alloys: before casting aluminium alloys, the molten metal can be treated in order to improve the microstructure and properties of alloys by addition of small quantities of certain "modifying" elements.
The pouring of molten metal into the mould: this is one of the critical steps in foundry technology, since the behaviour of the liquid and its subsequent solidification and cooling determine whether the cast shape will be properly formed, internally sound and free from defects.
The chill casting processes, such as gravity, low-pressure and high-pressure die casting processes: the essential feature of chill casting is the use of permanent metal moulds, into which the molten alloy is either poured directly or injected under pressure, giving rise to the separate processes of gravity and low/high pressure die casting. Permanent moulds offer obvious advantages in terms of simplicity of production for large quantities of parts, but are subject to limitations yet to be discussed.
The heat treating process applied to high-pressure die castings: conventional die castings are utilised to produce many products but unfortunately the presence of porosity limits the application. In addition to porosity, the microstructure inherent with conventional die casting could not meet the mechanical requirements needed for many applications. Subsequent heat treating, which can positively alter the microstructure, is rarely possible due to defects that emerge during thermal processing, such as blistering.
36
Tavakoli, Shahab. "Modélisation du cycle thermique des moules de fonderie sous pression." Thesis, Paris 10, 2014. http://www.theses.fr/2014PA100095.
Full textAbstract:
La réduction de la masse des véhicules, notamment des Groupes Motopropulseurs contribue à la réduction des émissions polluantes. Aujourd’hui afin d’aboutir à cet objectif, la conception de pièces automobiles (Carter Mécanisme, Carter Cylindre) en matériau allégé tel que l’aluminium et ses alliages est en plein essor. Pour la production de grande série, ces alliages sont mis en œuvre par le procédé de fonderie ‘’Aluminium sous pression’’.Ce procédé utilise des moules métalliques. La maîtrise du comportement thermique du moule : chauffage, refroidissement interne (par circuit) et externe, est un point clef pour la qualité et la cadence de production.Dans ce mémoire, le processus industriel est détaillé depuis la fermeture du moule et l’injection du métal liquide jusqu’à l’ouverture du moule et l’extraction de la pièce (carter mécanisme RENAULT). Ensuite, le design détaillé du moule, les différentes générations de circuit de refroidissement et les paramètres de chaque étape de la fabrication utilisés compte tenu du système de refroidissement actuel sont présentés. Le circuit de refroidissement du moule est aujourd’hui positionné dans le moule de façon empirique. Le but ultime de cette thèse est de donner les éléments clés de la conception du circuit de refroidissement d’un point vue thermique. Pour cela, une modélisation complète du phénomène a été réalisée et validée par 8 thermocouples et la position du system de refroidissement a été définie a partir des équations thermiques. Le cycle thermique du moule a été donc optimisé et nous a permis d’abaisser et d’homogénéiser les champs de température à la surface du moule pendant la production en vue d’une augmentation de la productivité, la santé des pièces et la durée de vie du mouleReducing the weight of vehicles, specially the powertrain Group, contributes to the reduction of the emissions. Today, in order to achieve this objective, the automobile parts conception (Housing gear box, Cylinder block) in lightweight materials such as aluminum and its alloys is increasing. For the mass production, aluminum alloys are formed by a foundry process called ‘’High Pressure Die Casting’’.This process uses the metal molds. Control the thermal behavior of the mold : Heating, intern cooling (by circuit) and extern cooling, is a key point to ensure castings quality and rate of production.In this thesis, the industrial process has been detailed since the mold closing and aluminum melting injection in the die, to the mold opening time and the part (Gearbox RENAULT) ejection. Then, the mold design details, different generation of the cooling systems and the parameters of each step of the manufacturing process taking into account the actual cooling system are presented. The actual cooling systems in the dies are positioned today in empirical way. The ultimate goal of this thesis is to provide the key elements for the cooling system conception from the thermal behavior point of view. For this one, a complete modeling of the phenomena has been realized and validated by 8 thermocouples and the cooling system position has been defined from the thermal equations. The thermal cycle of the die has been optimized and allowed us to reduce and homogenize the temperature fields on the die surface during the production. The rate of production, the castings quality and the lifetime of the die have been consequently increased
37
Milhem, Luc. "Fonderie sous pression du cuivre : étude du procédé et caractérisation du matériau." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMIR14.
Full textAbstract:
Ces travaux de recherche portent sur l’étude de l’injection du cuivre. Dans une optique d’amélioration des propriétés du cuivre injecté sous pression, deux grands thèmes de réflexion ont été abordés. La première voie de réflexion porte sur l’influence des paramètres de fusion et d’éléments d’alliages ajoutés en faible quantité sur les caractéristiques des démonstrateurs technologiques produits. La seconde partie discute de l’influence du procédé de fonderie en lui-même, notamment au travers de l’étude de deux paramètres : l’influence du régime d’écoulement du métal en fusion dans l’empreinte, et l’influence de l’emprisonnement de l’air sur les propriétés des pièces injectéesThis research focuses on the study of high pressure die casting (HPDC) of copper. In order to improve the properties of die-cast copper, two main issues were investigated. In the first part, attention is paid to the influence of melting parameters and of addition of alloying elements in small amounts on the characteristics of the specimen produced. The second part discusses the influence of the foundry process itself on properties of die cast part, in particular by studying two parameters : the metal flow type during cavity filling, and the air entrapment
38
Koplík, Jiří. "Snížení nákladů na výrobu odlitku litého tlakovým litím pomocí aplikace vysokoteplotního separátoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318779.
Full textAbstract:
The diploma thesis is focuses on new technology in of high pressure die casting industry. Attention is paid in particular to heating, cooling and the influence of the die lubricants on the quality of castings. theoretical knowledge was applied in practise. The optimization of the production cycle was carried out using a high temperature die lubricant and subsequent evaluation on particular casts in foundry KOVOLIT Modřice a.s.
39
Hamasaiid, Anwar. "Transferts thermiques interfaciaux en fonderie en moules métalliques d'alliages légers." Toulouse 3, 2007. http://www.theses.fr/2007TOU30249.
Full textAbstract:
L'objectif de ce projet est d'étudier les transferts thermiques interfaciaux pendant la solidification des alliages légers dans les procédés de fonderie par gravité et sous pression. Pour cela, nous avons développé des méthodes expérimentales et des capteurs appropriés permettant d'effectuer les mesures de température dans le moule et en surface de la pièce pendant le remplissage et la solidification. Nous avons également enregistré les paramètres procédés sur une installation de fonderie sous pression particulièrement bien instrumentée. Pour la mesure de température de surface de la pièce coulée, nous avons adapté une technique pyrométrique utilisant un pyromètre et une fibre optique auxquels nous avons ajouté un crystal de saphir transparent dans la gamme de longueur d'onde du pyromètre. Ainsi, nous avons effectué plusieurs centaines de cycles pendant lesquels trois alliages ASG03, AS9U3 et AZ91D ont été coulés par ces deux procédés. Les mesures de température ont été exploitées par une méthode inverse pour évaluer le coefficient d'échange thermique et la densité de flux de chaleur à l'interface pièce/moule pour chaque cycle effectué. Les résultats obtenus ont été comparés entre les diverses conditions de coulée et avec les microstructures des pièces produites. Nous avons proposé deux modèles analytiques pour la Résistance Thermique de Contact (RTC) à l'interface liquide/solide pour les deux conditions de contact rencontrées dans les deux procédés étudiés. .The present investigation is about the interfacial heat transfer during the solidification of light alloys in Gravity (GDC) and High Pressure (HPDC) Die Casting processes. The study consists of three principle fields, experimental, analytical and modelling. The Experimental activity involves measuring the temperature around the casting-die interface, in the mould and at the surface of the castings and other process parameters during die filling and solidification. For this purpose, suitable experimental methods and sensors have been developed. Particularly a pyrometric measurement method has been adapted to measure the casting surface temperature during its solidification. Hundredths of trials were performed using Al-7Si-0. 3Mg, A-9Si-3Cu and AZ91 D alloys during the two investigated processes. From the temperature measurements, interfacial heat transfer coefficient and heat flux density have been evaluated using an inverse method. The obtained results have been analysed with regards to the various process parameters and to the microstructure of the castings. .
40
Ferraro, Stefano. "Influence of trace elements on secondary die-cast aluminium alloys." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423822.
Full textAbstract:
Recycling play a key role on saving of natural resources and on reducing pollution. The recycling of aluminium alloys is also cost-effective, since it reduce the material cost and creates a considerable energy-saving. The use of recycled Al alloys (usually called secondary) has improved in recent years also because of their comparable mechanical properties with primary aluminium alloys.
During the production of secondary aluminium alloys, the scrap are mixed regardless of their specific chemical composition, and then master alloys or pure elements are added to the molten metal. Furthermore, certain impurity elements are either difficult or expensive to remove, and their role in mechanical properties can be important. Due to the presence of these additional trace elements, a number of complex intermetallic phases can therefore form in multi-component Al-Si alloys. Mechanical and physical properties of alloys and castings are strongly related to sizes, morphologies and distribution of these intermetallic phases, which are in turn a function of alloy composition and cooling rate.
The Al–Si based alloys are transversally used in different foundry processes. Among all the technologies, high-pressure die-casting (HPDC) represents the most common process to produce automotive components by secondary Al–Si alloys because it allows one to increase the production by lowering the cycle time and to obtain economically components with complex geometries and high quality surface.
The effects of trace elements and intermetallics phases on features of aluminium castings are still not fully understood, especially when components are made by means of HPDC process. The motivation of the research presented in this doctoral thesis was, therefore, to fill this gap in knowledge. The study has aimed at understanding the influence of various trace elements on the microstructure and mechanical properties of secondary die-cast aluminium alloys and, in particular, on secondary AlSi9Cu3(Fe) die-cast alloys.
A literature review and a sufficient background of previously reported results on the influence of trace elements on the features of aluminium alloys as well as the formation of intermetallic phases were carried out. It was found that the mechanical and microstructural analysis generally referred to primary cast Al alloys with low concentration of trace elements outside of those studied. Furthermore the samples were usually produced on gravity die-cast, while some intermetallics phases were frequently observed in high-pressure die-casting, where higher cooling rates and different feeding conditions exist.
Special attention has been given to:
The effects of Bismuth addition on secondary die-cast aluminium alloys: Bismuth substitute the lead in free-cutting wrought Al alloys, and this is leading to a steady increase of Bi content in secondary Al alloys due to the recycling process.
The nucleation temperature of primary Fe-rich intermetallic compounds, as function of Fe, Mn and Cr content and cooling rate: Fe-rich phases have a high specific gravity and tend to segregate to the bottom of aluminium melts and holding furnaces. These phases form primary solid particles, generally called sludge, thus reduce the effective capacity of the furnace.
The influence of Fe, Mn and Cr addition, separately or in combination, on the microstructural and mechanical characteristics of secondary die-cast aluminium alloys: sludge crystals are hard and brittle compact inclusions which can compromise the machining operations, with a considerable effects on the cutting tool life, and even more degrade the mechanical and physical properties of the component. As recycling of aluminium alloys becomes more common, sludge will be a problem of increasing importance due to the concentration of Fe, Mn and Cr in the scrap cycle.Il riciclaggio gioca un ruolo chiave sul risparmio delle risorse naturali e sulla riduzione dell'inquinamento. Il riciclo dell'alluminio è oltretutto economicamente conveniente, in quanto riduce il costo del materiale a fronte di un considerevole risparmio energetico. L'utilizzo di leghe di alluminio riciclate (comunemente chiamate leghe secondarie) è aumentato negli ultimi anni anche grazie alle loro proprietà meccaniche, le quali sono in alcuni casi comparabili con le leghe di alluminio primarie. Durante il processo di produzione dell'alluminio secondario i rottami vengono mescolati assieme indipendentemente dalla loro composizione chimica specifica. Al termine del processo fusorio la composizione viene regolata tramite l'aggiunta di leghe madri o di metalli puri. Tuttavia alcune impurezze presenti nel rottame rimangono all'interno della lega in quanto il loro processo di rimozione è complicato o non economicamente conveniente. A causa della presenza di questi elementi in traccia, un certo numero di fasi intermetalliche complesse si può formare nei getti. Di conseguenza le proprietà meccaniche e fisiche dei componenti in lega di alluminio sono fortemente correlate alla dimensione, alla morfologia e alla distribuzione di tali fasi intermetalliche, le quali sono a loro volta funzione della composizione della lega e della velocità di raffreddamento del metallo. Grazie alle loro elevata colabilità, le leghe Al-Si sono molto utilizzate in tutti i processi di fonderia. Tra le diverse tecnologie, la pressocolata (HPDC - high-pressure die-casting) rappresenta il processo più comune per la produzione di getti di alluminio nel settore automotive. Questa tecnologia permette di ottenere componenti con geometrie complesse e un'ottima finitura superficiale con una riduzione dei costi grazie alla elevata produttività e al basso tempo ciclo. Gli effetti degli elementi in traccia e delle fasi intermetalliche sulle proprietà dei getti in alluminio non sono ancora del tutto noti, soprattutto quando i componenti sono prodotti tramite pressocolata. Obiettivo di questo lavoro di dottorato di ricerca era perciò quello di supplire a queste lacune. Lo scopo del presente lavoro è studiare l'influenza di diversi elementi in traccia sulla microstruttura e sulle proprietà meccaniche di getti in lega secondaria di alluminio prodotti mediante pressocolata, ed in particolare nella lega AlSi9Cu3(Fe). In prima analisi, è stata condotta una recensione della letteratura sull'influenza degli elementi in traccia sulle proprietà delle leghe di alluminio e sulla formazione delle fasi intermetalliche. Questo ha permesso di constatare che le caratteristiche meccaniche e microstrutturali legate alla presenza di fasi indesiderate sono normalmente valutate in getti prodotti con leghe primarie di alluminio, in cui è presente una bassa concentrazione di impurezze al di fuori di quelle studiate. Inoltre i campioni studiati sono generalmente prodotti mediante colata in gravità, mentre alcune fasi intermetalliche sono tipiche della pressocolata, in cui la velocità di raffreddamento è molto più elevata e sono presenti diverse condizioni di alimentazione e di riempimento dello stampo. Nel presente lavoro è stata posta particolare attenzione a: Gli effetti dell'aggiunta di Bismuto nelle leghe di alluminio secondarie pressocolate: il Bismuto ha sostituito il Piombo nelle leghe di alluminio da deformazione plastica ad alta lavorabilità alle macchine utensile. Questo ha comportato un aumento del contenuto di Bismuto nelle leghe secondarie di alluminio a causa del processo di riciclaggio degli sfridi di lavorazione. La temperatura di nucleazione dei precipitati intermetallici ricchi in Ferro in funzione della velocità di raffreddamento e della concentrazione in lega di Ferro, Cromo e Manganese: le fasi ricche in ferro hanno un elevata densità e tendono a segregare sul fondo del fondo del forno di mantenimento. L'insieme di queste fasi primarie forma una fanghiglia, chiamata sludge, che riduce l'effettiva capacità del forno. L'effetto dell'aggiunta di Ferro, Cromo e Manganese, singolarmente o in combinazione tra di loro, sulle caratteristiche microstrutturali e meccaniche delle leghe di alluminio secondarie pressocolate: le particelle di sludge sono inclusioni compatte dure e fragili, le quali possono compromettere le operazioni di lavorazione meccanica, con una conseguente riduzione della durata degli utensili, ed una marcata riduzione delle proprietà meccaniche e fisiche del componente. Il problema delle particelle di sludge nelle leghe secondarie di alluminio assume un'importanza sempre maggiore a causa dell'aumento del riciclo dell'alluminio e della presenza di Fe, Mn e Cr nel ciclo del rottame.
41
Maurer, Simon Alexander. "Multidisziplinäre Formoptimierung modularer Grundgeometrien für Druckgussbauteile mit strömungs- und strukturmechanischen Zielfunktionen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-197331.
Full textAbstract:
Am Anfang des Entwicklungsprozesses eines Gussbauteils für die Automobilbranche steht klassischerweise die konstruktive Ausarbeitung und die Auslegung auf Zielgrößen, wie Festigkeit, Steifigkeit bzw. die Erfüllung der Crashlasten. Im nächsten Entwicklungsschritt wird, oftmals in Zusammenarbeit mit externen Lieferanten, das Werkzeugkonzept entwickelt und die Herstellbarkeit mit Hilfe von Gießsimulationen abgesichert. Bei der Fertigung verursachen streuende Prozessgrößen, wie etwa Geschwindigkeits- oder Temperaturniveaus, Schwankungen in der Leistungsfähigkeit des Endprodukts (z. B. lokale Bruchdehnung oder Zugfestigkeit). Maßnahmen zur Erhöhung der Prozessstabilität und zur Reduktion des Verschleißes konzentrieren sich oftmals auf die erfahrungsbasierte Verbesserung des Fertigungsprozesses und Anpassungen des Anguss- und Überlaufsystems. Größere Änderungen der Bauteilgeometrie sind häufig aus zeitlichen Gründen nicht mehr möglich. Das Ziel dieser Arbeit ist es daher, optimierte modularisierte Grundgeometrien, wie Rippen oder Umlenkungen, mit Hilfe von numerischen Formoptimierungen zu entwickeln, um diese schon von Anfang an in der Bauteilentwicklung zu berücksichtigen. Als Zielfunktionen dienen strömungs- und strukturmechanische Kenngrößen, um einerseits verschleißfördernde Mechanismen und füllungsbedingte Defekte zu reduzieren und andererseits die Beanspruchbarkeit zu erhöhen. Bei den Untersuchungen wird zusätzlich die Robustheit des Ergebnisses analysiert, um Verbesserungspotenziale auch bei streuenden Randbedingungen realisieren zu könnenThe virtual development process of an automotive casting part usually begins with classical design tasks and analyses of material strength, stiffness and crash load cases. In the next step, often in cooperation with external suppliers, the tooling concept is developed and casting simulations are used to ensure manufacturability. During manufacturing there is a scatter in process parameters, such as flow velocity or temperature levels, which in turn cause a scatter in the performance of the final product (e.g. local elongation at fracture or ultimate tensile strength). Means to increase process stability and yield are often limited to knowledge-based improvements of the manufacturing process parameters and adaptations of the gating and overflow system. Major changes to the part geometry are usually no longer possible due to project time constraints. Therefore it is the goal of this thesis to optimize modularized basic geometries, like ribs or bends, by using numerical shape optimizations and employ them right from the beginning of the part development process. For the objective functions of the optimizations the disciplines of fluid dynamic filling and the resulting structural behaviour are considered. In addition, the resulting shape is analyzed with regards to robustness towards scatter in manufacturing operating conditions. By using these new modularized geometries the overall robustness of the final product is expected to be increased
42
Lui, Ying Bik. "The fluid dynamics of pressure die casting processes." Thesis, Brunel University, 1997. http://bura.brunel.ac.uk/handle/2438/5224.
Full textAbstract:
The main text of the thesis consists of seven chapters. Following the literature survey, the work in Chapter 2 focuses on the study of the whole process of pressure die casting. The necessity of reclassification against the traditional 'three-stage' description is introduced in order to build a new basic tenet in constructing theoretical and practical investigations, which leads to the creation of fluid dynamic mathematical models of the process. On the basis of Chapter 2, Chapter 3 concentrates on dealing with the computer simulation of filling flow patterns occurring in the third stage that play the most important role in the process. The Simplified Marker And Cell (SMAC) method is used to obtain the computational results of the filling patterns of pressure die casting processes. On the basis of the computational analysis of typical examples, the viscosity, gravitational force and velocity effects on the overall filling pattern are examined, that lead to a validation of the important hypothesis that an ideal liquid can be used in numerical simulation of filling patterns and this enables one to achieve a more effective computer program for a complex cavity by quasi-3D or 3D models. Chapter 4 treats a specific problem of the residual flow that exists in the final (fifth) stage of the process. Mathematical models of residual flow are derived. Chapter 5 mainly consists of two parts. The first part deals with the application of similitude laws for simulating flows in pressure die casting processes. Detailed analyses and criteria on different relationships between model and prototype are given in order to correct previously offered formulae by Eckert (1989). The results of numerical simulation presented in Chapter 3 are also extended to validate the similitude criteria. The second part of Chapter 5 presents the use of a charge coupled device(CCD) for studying the diversity of fluid motion including the filling pattern, residual flow, thermals and air entrapment during cavity-fill and post cavity-fill within a one single shot cavity filling in water analogue experiments. A discussion, conclusions and suggestions for further study of the subject concerned are presented in Chapters 6 and Chapter 7.
43
Shi, XinMei. "Defect minimizing control of low pressure die casting." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42720.
Full textAbstract:
Controlling and eliminating defects, such as macro-porosity, in die casting processes is an on-going challenge for manufacturers. Current strategies for eliminating macro-porosity focus on the execution of pre-set casting cycles, die structure design or the combination of both. To respond to process variability and mitigate its negative effects, advanced process control methodology has been developed to dynamically drive the process towards optimal dynamic or static operational conditions, hence minimizing macro-porosity in the casting.
In this thesis, a Finite Element heat transfer model has been developed to predict the evolution of temperatures and the volume of encapsulated liquid in a casting with a high propensity to form macro-porosity. The model was validated by comparison to plant trial data. A virtual process has then been developed based on the model to simulate the continuous operation of a real process, for use as a platform to evaluate a controller’s performance.
Since macro-porosity cannot be measured during casting, die temperature has been used as an indirect indicator of this defect. A model-based methodology has been developed to analyze the correlation between die temperature and encapsulated liquid volume, a precursor to the formation of macro-porosity. This methodology is employed to assess the suitability of different in-cycle die temperatures for use as indicators of macro-porosity formation. The optimal locations have then been determined to monitor die temperatures for the purpose of minimizing macro-porosity.
A nonlinear state-space model, based on data from the virtual process, has been developed to provide a reliable representation of this virtual process. The control variable-driven portion exhibits linear dynamic behavior with nonlinear static gain. The resulting MIMO state-space model facilitated the design of a controller for this process.
Finally, the performance of the nonlinear model-based predictive controller was evaluated using the virtual process. Independent of the initial state of the process - i.e. steady state or startup, the controller exhibited the capability to automatically adjust the process toward the dynamic or static optimal operational condition during disturbances examined. The advanced control methodology developed for LPDC provides a novel solution to improve the operational conditions in die casting process.
44
Vicario, Gomez Iban. "Influence des nano-particules d’alumine (Al2O3) et de di-borure de titane (TiB2) sur la microstructure et les propriétés de l’alliage Al-Si9-Cu3-Fe1 pour des applications de fonderie à haute pression." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14420/document.
Full textAbstract:
Ce travail est dédié á l´étude de l´influence de nano-particules de alumina (Al2O3) et de di-borure de titane (TiB2) sur la solidification, la microstructure et les propriétés thermiques et mécaniques de l´alliage d´aluminium renforcés, Al-Si9Cu3Fe1. Les matériaux ont été obtenus par un procédé de fonderie à haute pression en coulant les alliages dans les mêmes conditions que les alliages non renforcés correspondants.On a constaté que les particules de Al2O3 et de TiB2 ont une influence directe sur les caractéristiques de l´alliage telles que la microstructure, la précipitation des phases pendant la solidification et les propriétés mécaniques et électriques. On a ainsi montré que les particules de Al2O3 et de TiB2 peuvent être utilisées pour ajuster les caractéristiques des alliages et obtenir des propriétés spécifiques pour des applications dans les secteurs de matériaux légersThe work has been focused on the study of the influence of TiB2 and Al2O3 nano-particles (up to 1 wt. %) on the properties and physical features of an aluminium casting alloy, Al-Si9Cu3Fe1.Samples have been obtained through the High Pressure Die Casting (HPDC) process and compared with unreinforced samples obtained at the same conditions. It has been observed that the Al2O3 and TiB2 particles have a direct influence on several features of the alloy such as the microstructure and precipitating phases as well as in the improvement of the soundness and mechanical and electrical properties. Al2O3 and TiB2 particles can be used to tailor the properties of the alloy and to match the specifications of light weight applications
45
Jain, Rajesh (Rajesh Baboola) Carleton University Dissertation Engineering Mechanical and Aerospace. "A 2D transient thermal analysis of pressure die casting." Ottawa, 1994.
Find full text
46
Dini, Hoda. "As-cast AZ91D magnesium alloy properties : Effects of microstructure and temperature." Doctoral thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Material och tillverkning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-38148.
Full textAbstract:
Today, there is an essential need for lightweight, energy-efficient, environmentally benign engineering systems, and this is the driving force behind the development of a wide range of structural and functional materials for energy generation, energy storage, propulsion, and transportation. These challenges have motivated the use of magnesium alloys for lightweight structural systems. Magnesium has a density of 1.74 g/cm3, which is almost 30% less than that of aluminium, one quarter of steel, and almost identicalto polymers. The ease of recycling magnesium alloys as compared to polymers makes them environmentally attractive, but their poor mechanical performance is the primary reason for the limited adoption of these alloys for structural applications. The Mg-Al-Zn alloy AZ91D exhibits an excellent combination of strength, die-castability, and corrosion resistance. However, its mechanical performance with regard to creep strength, for example, at evaluated temperatures is poor. Moreover, very little is known about the correlation between its mechanical properties and microstructural features. This thesis aims to provide new knowledge regarding the role played by microstructure in the mechanical performance of the magnesium alloy. The properties/performance of the material in relation to process parameters became of great interest during the investigation. An exhaustive characterisation of the grain size, secondary dendrite arm spacing (SDAS) distribution, and fraction of Mg17Al12 was performed using optical and electron backscatter diffraction (EBSD). These microstructural parameters were correlated to the offset yield point (Rp0.2), fracture strength, and elongation to failure of the material. It was proposed that the intermetallic phase, Mg17Al12, plays an important role in determining the mechanical and physical properties of the alloy in a temperature range of room temperature to 190°C by forming a rigid network of intermetallic. The presence of this network was confirmed by studying the thermal expansion behaviour of samples of the alloy containing different amounts of Mg17Al12. A physically based constitutive model with a wide validity range was successfully adapted to describe the flow stress behaviour of AZ91D with various microstructures. The temperature-dependent variables of the model correlated quite well with the underlying physics of the material. The model was validated through comparison with dislocation densities obtained using EBSD. The influence of high-pressure die-cast parameters on the distortion and residual stress of the cast components was studied, as were distortion and residual stress in components after shot peening and painting. Interestingly, it was found that intensification pressure has a major effect on distortion and residual stresses, and that the temperature of the fixed half of the die had a slight influence on the component's distortion and residual stress.Numera finns det ett väsentligt behov av lätta, energieffektiva och miljövänliga tekniksystem. Detta behov är drivkraften för utveckling av ett brett utbud av material för energigenerering, energilagring, framdrivning och transport. Dessa utmaningar motiverade användningen av magnesiumlegeringar för lättviktskonstruktioner. Magnesium har en densitet på 1,74 g/cm3, vilket är ca 30% lägre än för aluminium, en fjärdedel av densiteten för stål och nästan i nivå med många polymerer. Då magnesiumlegeringar dessutom är lätta att återvinna, jämfört med polymerer, gör det dem miljömässigt attraktiva. Låga mekaniska egenskaper är den främsta orsaken till begränsad användning av dessa legeringar för lastbärande tillämpningar. Mg-Al-Zn-legeringen AZ91D uppvisar en utmärkt kombination av styrka, gjutbarhet och korrosionsbeständighet. Dess mekaniska egenskaper vid förhöjd temperatur, som tex kryphållfasthet, är låga. Dessutom är korrelationen mellan mikrostruktur och mekaniska egenskaper oklar. Denna avhandling syftade till att ge ny kunskap om mikrostrukturens roll för magnesiumlegeringars mekaniska egenskaper. Slutligen var materialets egenskaper i förhållande till processparametrar vid tillverkningen av stort intresse. En omfattande karaktärisering av kornstorleks-, sekundära dendritarmavstånds (SDAS)-fördelning och fraktion av Mg17Al12 utfördes med hjälp av optisk mikroskopering och diffraktion av bakåtspridda elektroner (EBSD). Mikrostrukturen korrelerades till sträckgränsen (Rp0.2), brottstyrkan och brottförlängningen. Det föreslogs att den intermetalliska fasen, Mg17Al12, spelar en viktig roll vid bestämning av legeringens mekaniska och fysikaliska egenskaper vid temperaturintervall från rumstemperatur upp till 190°C genom att bilda ett styvt nätverk av intermetaller. Uppkomsten av ett sådant nätverk stöddes genom en studie av den termiska expansionen av legeringen för olika fraktioner av Mg17Al12. En fysikalisk konstitutiv modell med ett brett giltighetsområde användes framgångsrikt för att beskriva det plastiska flytbeteendet hos AZ91D för olika mikrostrukturer. De temperaturberoende variablerna i modellen korrelerade ganska väl med materialets underliggande fysik. Modellen validerades genom att jämföra dislokationstätheten som predikterades av modellen och den med EBSD uppmätta dislokationstätheten. Påverkan av pressgjutningsparametrar på geometrisk tolerans och restspänning hos de gjutna komponenterna studerades. Vidare studerades geometrisk tolerans och restspänning av komponenter efter pening och målning. Intressant nog hade eftermatningsfasen en stor effekt på geometrisk tolerans och restspänningar. Dessutom hade temperaturen på den fasta formhalvan av verktyget även ett visst inflytande på komponentens geometriska tolerans och restspänning.
47
Moayedinia, Sara. "Quantification of cooling channel heat transfer in low pressure die casting." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/48509.
Full textAbstract:
The focus of this project is to develop a methodology to quantitatively describe the heat transfer in the cooling channels of the low-pressure die casting process, which is the dominant commercial technology for the production of aluminum automotive wheels, and to successfully implement the methodology in a numerical model of the casting process. Towards this goal, an algorithm capable of calculating heat transfer coefficient (HTC) based on process parameters and surface temperature within the cooling channel is developed. The algorithm was implemented in the form of a user-defined subroutine in a 3-D thermal model of the Low Pressure Die Casting (LPDC) process developed in the commercial finite element analysis package in ABAQUS.
The cooling channel HTC’s are often input into thermal models as an average constant value derived based on trial-and-error. The trial-and-error process to obtain the HTCs in the cooling channel involves, prescribing a trial set of HTC values and comparing the results of the casting simulation with thermocouple measurements. The trial cooling channel HTCs are then adjusted until a reasonable fit to the temperature measurements are achieved. The trial-and-error process is generally time consuming and does not accurately describe the physical phenomenon occurring in the cooling channel during casting. The constant cooling channel HTCs obtained through the trial-and-error process are tuned to a given set of operating conditions, compromising the utility and generality of the model.
To provide data necessary for model validation, casting plant trials were performed at Canadian Autoparts Toyota Inc. in Delta, British Columbia. The trials included temperature measurements at pre-determined locations within the top, side and bottom dies. The validity of HTC calculations have been assessed by comparing the predicted temperature history of the subroutine-based model with the measured thermocouple data collected during the casting cycle and also comparing the model predictions with the base-case model with constant cooling channel HTC.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
48
Gibson, Catherine. "Synthesis and characterisation of porous PMMA for use in the pressure casting of ceramics." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/synthesis-and-characterisation-of-porous-pmma-for-use-in-the-pressure-casting-of-ceramics(33eb67ad-c8fd-44ee-9e2c-a3c04a2efe53).html.
Full textAbstract:
Gypsum has been used almost exclusively as the mould material for casting sanitary-ware due to its high versatility, strength and homogenous pore distribution. However gypsum moulds have a number of disadvantages including deterioration on contact with water, deformation, long set times and short mould lives such that a large number of moulds are required for a commercial manufacturing processes. These drawbacks have led to attempts to find a new synthetic material to create moulds with similar properties to gypsum with respect to fine homogeneous pores, but with increased durability. Porous PMMA was developed in 1971 for the purpose of moulding ceramics. The basic approach to making the materials has remained unchanged since its commercial introduction with few academic studies undertaken on the formulations. This thesis describes an investigation into porous PMMA from an academic perspective studying the mechanism of formation of the materials and the role of the components in polymerisation. In particular: the surfactant type and level, monomer type, water to monomer ratio and bead size have been probed to assess their effect on the porosity and mechanical strength. A particular importance has been placed on the commercial viability of formulations because gypsum is a relatively inexpensive material and, due to its versatility and ease of manufacture, is still used throughout the ceramics industry. To increase cost competitiveness through spreading the higher cost of the raw materials and capital investment, the mechanical strength of porous PMMA materials has to be significantly greater to increase the number of casting cycles from each mould. In addition, to achieve competitive advantage in the marketplace, a deep understanding of the formulation was undertaken. This should allow for tailoring of the mould properties allowing for specialised moulds for different applications. In addition, this focused approach facilitates cost-savings allowing for the minimum input of raw materials. The thesis is a comprehensive body of work which looks individually at the components assessing their effect on the properties of the final material. In addition, the formation mechanism of the materials has been explored by breaking down the polymerisation into key stages. Highlighted is the excessive use of surfactant in a commercial formulation and the influence of plasticisation of the ligaments by the surfactant and excess monomer. The theory behind the polymerisation process, which generates the ligaments and traps the polymer beads in an immobile matrix, is developed; forming a comprehensive understanding of the formation of porous PMMA materials and factors influencing their development and final properties.
49
Ogden, Sam. "High-Pressure Microfluidics." Doctoral thesis, Uppsala universitet, Mikrosystemteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208915.
Full textAbstract:
In this thesis, some fundamentals and possible applications of high-pressure microfluidics have been explored. Furthermore, handling fluids at high pressures has been addressed, specifically by creating and characterizing strong microvalves and pumps. A variety of microstructuring techniques was used to realize these microfluidic devices, e.g., etching, lithography, and bonding. To be able to handle high pressures, the valves and pumps need to be strong. This necessitates a strong actuator material. In this thesis, the material of choice is paraffin wax. A new way of latching paraffin-actuated microvalves into either closed or open position has been developed, using the low thermal conductivity of paraffin to create large thermal gradients within a microactuator. This allows for long open and closed times without power consumption. In addition, three types of paraffin-actuated pumps are presented: A peristaltic high-pressure pump with integrated temperature control, a microdispensing pump with high repeatability, and a pump system with two pumps working with an offset to reduce flow irregularities. Furthermore, the fundamental behavior of paraffin as a microactuator material has been explored by finite element modeling. One possibility that arises with high-pressure microfluidics, is the utilization of supercritical fluids for different applications. The unique combination of material properties found in supercritical fluids yields them interesting applications in, e.g., extraction and cleaning. In an attempt to understand the microfluidic behavior of supercritical carbon dioxide, the two-phase flow, with liquid water as the second phase, in a microchannel has been studied and mapped with respect to both flow regime and droplet behavior at a bi-furcating outlet.
50
Misner, Scottie. "High Blood Pressure." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2010. http://hdl.handle.net/10150/146443.
Full text