Дисертації з теми "Quality of castings"
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1
Dewhirst, Brian A. "Optimization of the heat treatment of semi solid processed A356 aluminum alloy." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-111705-111503/.
Повний текст джерелаАнотація:
Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: microstructure; casting; Fluid Bed; Quality Index; Aluminum; A356; heat treatment; SSM; Semi Solid Metal Includes bibliographical references. (p.105-106)
2
Khaled, Iman. "A study of some of the foundry processing factors influencing the quality of titanium alloy investment castings." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5989/.
Повний текст джерелаАнотація:
Titanium aluminide alloys are prone to extensive shrinkage porosity, particularly interdendritic layer porosity. This research aims to develop a better understanding of shrinkage porosity in Ti-46Al-8Nb alloy and how to minimize it. Practical measurements in conjunction with computer simulations were carried out in order to study the effects of cooling rate and temperature gradient on shrinkage porosity in Ti-46Al-8Nb investment castings, through investigating the influence of casting geometry, specifically mould taper on cylindrical bars, and preheating mould temperature on the macrostructure and the formation of shrinkage porosity. The interface heat-transfer coefficient of the ceramic shell/surroundings was determined using measured cooling curves obtained in 200 mbar of Argon and in vacuum. Furthermore, the alloy/mould interfacial heat transfer coefficient was estimated and was verified by comparing measured and predicted cooling curves of Ti-46Al-8Nb. The Niyama criterion function was validated to predict shrinkage-related porosity in Ti-46Al-8Nb castings, through either thermal or tilt-filling ProCastTM simulation models. Positions in a casting with Niyama values above 4 (°C. min)0.5cm-1; (3 (K. s)0.5mm-1); could be considered completely sound. The critical value of the Niyama function was 2 (°C. min)0.5cm-1; (1.5 (K. s)0.5mm-1); below which the position tested was susceptible to macroshrinkage porosity.
3
Polyakova, Irina. "Untersuchung der kognitiven Modellierung zur Gussstückqualitätsverbesserung." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-130996.
Повний текст джерелаАнотація:
Als Ergebnis der vorliegenden Arbeit wurde ein nützliches Hilfsmittel auf der Basis der kognitiven Herangehensweise zur Verbesserung der Effizienz der Managemententscheidungen für die Gussausschussverringerung und Qualitätsverbesserung in den Gießereien entwickelt. Das Werkzeug hilft dem Technologen, den Mechanismus des Gussfehlerentstehungsprozesses aufzudecken, die Logik der Gussfehlerentstehung zu verstehen und die präventiven Maßnahmen zu testen. Man kann das Werkzeug täglich im Betrieb benutzen, um die strategischen und operativen Entscheidungen rasch und ohne Durchführung der kostspieligen und komplizierten Versuche zu treffen. Auf diese Weise können Kosten und Zeit eingespart werden.
4
Дячок, Дарія Романівна. "Оптимізація технологічного процесу відтворення художніх виробів у металі". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/43657.
Повний текст джерелаАнотація:
Дипломна робота: 86 с., 20 рис., 30 табл., 16 посилань.
Мета роботи – оптимізація технологічних процесів відтворення у
металі копій двох художніх виробів за наявними неметалевими
оригіналами.
Методика дослідження – виготовлення силіконових та гіпсових
прес-форм із різними варіантами ливникової системи; виготовлення гіпсо кремнеземистих ливарних форм, їх прожарювання та заливання при різних
температурах; контроль параметрів якості виливків (шорсткість поверхонь
та наявність ливарних дефектів).
Результати та їх новизна – теоретично і практично установлено
придатність силіконових прес-форм для виготовлення якісних виливків із
легкоплавких (олов’яно-свинцевих) сплавів; досліджено параметри
технологічних процесів відтворення у металі копій художніх виробів;
виготовлено серію якісних художніх виливків із олов’яно-свинцевого і
мідного сплаву.
Основні показники – в результаті виконання роботи визначено
оптимальні параметри технологічних процесів виготовлення художніх
виробів. Відлито статуетку «Вікінг» масою 0,099 кг із олов’яно-свинцевого
сплаву та масою 0,073 к із латуні Л63, а також статуетку «Кельт» масою
0,468 кг із латуні Л63. Вироби не мають ливарних дефектів, шорсткість
поверхонь виливка «Кельт» не перевищує 12,5 мкм, а «Вікінг» - 6,3 мкм.
Область застосування – Художнє та ювелірне литво унікальних
виробів.
Економічна ефективність – 214 137,4 грн.
Прогнозні припущення щодо розвитку об’єкта дослідження – за
аналогією із дослідженими технологічними процесами, розроблення схем
виготовлення схожих за розмірами та складністю литих художніх виробів в
умовах дрібносерійного виробництва.Bachelor’s dissertation: 86 pages, 20 figures, 30 tables, 16 references. The purpose of the work – optimize the technological processes of reproduction in metal copies, two works of art, according to the available non metallic originals. Research methodology – production of silicone and plaster molds with different variants of the foundry system; production of plaster-silica molds, their calcination and pouring at different temperatures; control of quality parameters of castings (surface roughness and the presence of casting defects). Results of the work and their novelty – theoretically and practically established the suitability of silicone molds for the manufacture of high-quality castings from low-melting (tin-lead) alloys; the parameters of technological processes of reproduction in metal copies of art products are investigated; made a series of high-quality art castings from tin-lead and copper alloy. The main indicators – as a result of work the optimum parameters of technological processes of manufacturing of art products are defined. A 0.099 kg Viking figure made of tin-lead alloy and 0.073 kg L63 brass was cast, as well as a 0.468 kg Celt statue made of L63 brass. The products do not have casting defects, the surface roughness does not exceed 12,5 microns and 6,3 microns, Areas of application – art and jewelry casting of unique products. Economic efficiency – UAH 214,137.4. Predictive assumptions about the development of the object of study – by analogy with the studied technological processes, the development of plans for the manufacture of similar size and complexity of cast art products in small scale production.
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Krejčí, Martin. "Nedestruktivní zkoušení odlitků ozubených kol." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228720.
Повний текст джерелаАнотація:
This diploma thesis resolves aplication of particular non-destructive testing methods while producing castings of steel wheels and quality control of this process. There are described fundamentals of flaw detection, determination of flaw-generation cause and suggestions for optimalization of casting process and increasing of its quality.
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Mahapatra, Rama Ballav. "Mould behaviour and product quality in continuous casting of slabs." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/29214.
Повний текст джерелаАнотація:
An extensive study has been conducted to elucidate mould behaviour and to examine its influence on product quality during continuous casting of slabs. The study essentially comprised of industrial measurements, mathematical modelling and metallographic examination. The industrial measurements consisted of mould temperature measurements; an operating slab mould was instrumented with 114 thermocouples and the temperature of the mould at different locations was successfully measured for a wide range of casting conditions. A three-dimensional heat flow model of the mould was developed to quantitatively characterize the heat fluxes in the mould from a knowledge of the mould temperature data. Futhermore, a one-dimensional solidification model was developed to simulate solidification of steel and also, a heat flow model was developed to examine the mould flux behaviour by characterizing the slag rim thickness at the meniscus. Slab samples collected during the industrial trial campaign were metallographically examined to study the different aspects of solidification in the mould, sub-surface structure, solidification bands, cracks and oscillation marks.
The thermocouple measurements revealed the occurrence of metal level fluctuation in the mould, the magnitude of which was appreciable. Thus, implementation of a metal level control system has been recommended. The time-averaged mould temperature data was converted into heat fluxes and it has been well demonstrated that a three-dimensional model of the mould wall was essential for accurate computation of heat fluxes in the mould. The measurements have clearly established the strong dependence of heat transfer in the mould on the mould flux employed during casting. A reduction in the viscosity and melting temperature of the mould flux will lead to enhancement of heat transfer in the mould. It was also found that the heat transfer in the mould can be influenced by changes in casting speed, submergence depth, steel carbon content; the effect of these variables on heat transfer has been explained mostly on the basis of their influence on the mould flux behaviour at the meniscus. Furthermore, heat extraction characteristics on the two broad faces were different which was a consequence of differences in mould flux behaviour resulting from differences in mould wall thickness between the two broad faces.
The heat-flux profiles were employed as a boundary condition in the solidification model to compute the shell thickness in the mould for a wide range of casting conditions. The casting speed has a significant influence on the shell profile in the mould; an increase in the casting speed led to a reduction in the shell thickness. The non-uniformity of the shrinkage of the solid shell in the mould was evident from the slab surface-temperature profile which clearly revealed the advantages of a non-linear taper of the narrow face compared to the conventional single taper. From a knowledge of heat-flux profile and metallographic analysis, a mechanism towards formation of longitudinal cracks/depression was formulated. Mathematical analysis performed on the mould flux at the meniscus revealed the presence of a slag rim adjacent to the mould wall; the dimensions of the slag rim thickness were computed at different casting speed and mould wall thickness. It was shown that oscillation marks are formed by the interaction of the slag rim with the partially solidified meniscus; the depth of the oscillation marks is strongly governed by the thickness of the slag rim at the meniscus.
This study has unambiguously shown that the dimension of the slag rim at the meniscus is quite critical from the standpoint of heat transfer and product quality of slabs. Based on the findings of the present study, for the first time, links have been established between the mould wall thickness and heat transfer in the mould. The slag rim thickness at the meniscus can be reduced by increasing the mould wall thickness. It is anticipated that an increase in the casting speed and thus, a corresponding increase in production rate can be accomplished by changing the design of the mould.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Cao, Xinjin. "Heat treatment of liquid metal : precipitation and sedimentation processing of liquid Al-11.5Si-0.4Mg alloy." Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369168.
Повний текст джерела
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Bommaraju, Ramaprasad V. "Mold behavior, heat transfer and quality of billets cast with in-mold electromagnetic stirring." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28628.
Повний текст джерелаАнотація:
Mold behavior, mold-related quality and the columnar-to-equiaxed transition influenced by in-mold EMS were examined by performing trials at two steel companies, metallurgical examination of the billet samples and mathematical modelling. The thermal fields in the walls of billet molds (102 X 102mm and 127 X 178mm) and in the cooling water were monitored by a system of thermocouples as the EMS was switched on and off during the continuous casting of several heats. The effect of electro-magnetic stirring on mold heat extraction was found to be negligible. The mold temperatures and cooling water temperatures are strongly dependent on the mold/billet gap which is affected by dynamic distortion of the mold tube. In the case of the square mold, the time-dependent mold distortion resulted from boiling adjacent to the cold face due to low water velocity and poor water quality. In the rectangular mold, differential expansion of the wide and narrow faces of the mold led to periodic wall movement at the midface causing cycling in the mold and water temperature. Both effects completely dominated any potential influence of EMS on mold heat extraction.
Cooling water velocities measured in separate experiments and the mold temperature profiles were input to a two-dimensional heat-flow model to establish mold heat-flux profiles. A steep taper of 2.6 %/m in the upper regions of the mold increased heat extraction compared to previously published heat-flux data in 0.8 %/m tapered-molds. However, due to the periodic wall movement in the rectangular mold, the heat flux declines to lower values periodically. The calculated heat flux profiles were employed in a one-dimensional transient heat flow model to predict superheat removal from the liquid pool under a variety of assumed fluid flow conditions. The major heat flow effect of EMS was inferred to be one of increasing the convective heat flow at the solidification front leading to earlier superheat extraction from the liquid steel.
Solidification structures in billet samples collected during the trials were examined. The columnar-to-equiaxed transition in continuous casting takes place provided all the superheat is removed from the melt and there is a sufficient density of nuclei present in the pool. At superheats of <20° C in the tundish, high heat extraction in the mold and remelting of the mold generated nuclei facilitate the removal of the superheat well within the mold and the columnar-equiaxed transition is triggered after 10-15 mm of shell growth on both the inside and outside radius faces. At higher superheat in the tundish, the liquid pool leaves the mold with residual superheat which takes longer to remove because of the declining fluid flow. Even though all the superheat is removed lower in the machine, the columnar-equiaxed transition occurs only if dendrite debris generated in the vicinity of the mold has survived in their descent through the superheated liquid. The effect of carbon on the columnar-to-equiaxed transition appears to stem from its influence on facilitating dendrite arm remelting and the survival of the dendrite fragments till the pool reaches sub-liquidus temperature. EMS extracts more superheat by maintaining a steep temperature gradient in the thermal boundary ahead of the solidification front and achieves an earlier columnar-equiaxed transition.
Electro-magnetic stirring appears not to affect either the average depth or the variation of depth of oscillation marks across a given face. However, the electro-magnetically driven flow dominates the turbulance at the meniscus due to the input stream and stabilizes a meniscus shape with the result that the oscillation marks are also of a well-defined shape unlike the unstirred billets.
No influence of EMS was found on the formation of "hooks" or the fine equiaxed crystal zone near the surface. The influence of EMS on inclining the growing dendrites appears to not come into effect until about 1 mm of shell has formed. It appears that the existence of the momentum boundary layer where the velocity of the rotating steel falls to zero at the surface is the reason for the absence of the influence of EMS on the subsurface solidification.
Rhomboidity and off-corner crack formation were found to depend, as reported by previous researchers, on mold distortion and its dynamic nature. The absence of any effect of EMS on these defects is due to its lack of effect on mold heat transfer and thus mold distortion.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Slagter, Alejandra. "Advanced Inspection of Surface Quality in Continuously Cast Products by Online Monitoring." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70634.
Повний текст джерела
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Bouhouche, Salah. "Contribution to quality and process optimisation in continuous casting using mathematical modelling." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:swb:105-6900128.
Повний текст джерелаАнотація:
Mathematical modelling using advanced approach based on the neural networks has been applied to the control and the quality optimisation in the main processes of steelwork such as the ladle metallurgical treatment and continuous casting. Particular importance has been given to the improvement of breakout prediction system and the reduction in the rate of false alarm generated by the conventional breakout detection system. Prediction of the chemical composition and temperature of liquid steel in the ladle has been achieved by neural networks and linear model. This prediction can be considered as a soft sensor. Slab surface temperature stabilisation on the basis of the casting events has been controlled by a neural networks algorithm, that gives an improvement in the surface temperature fluctuation in comparison to the conventional control system which is based on the PID controller. Quality monitoring and classification is also achieved by a neural network which is related to the breakout detection system. This technique achieves a classification of different defects based on the different alarm signal given by the breakout prediction system. Fault detection and process monitoring is developed using neural networks modelling. All models are developed on basis of practical operating database obtained from the iron and steel industry.
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Bouhouche, Salah. "Contribution to quality and process optimisation in continuous casting using mathematical modelling." Doctoral thesis, [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=966041208.
Повний текст джерела
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Saleem, Saud. "On the surface quality of continuously cast steels and phosphor bronzes." Doctoral thesis, KTH, Metallernas gjutning, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187718.
Повний текст джерелаАнотація:
This thesis work concerns about the importance of the cast surfaces, surface phenomenon such as the formation of the oscillation marks and exudation and related defects including cracks and segregation that happened during the continuous casting. All of the investigated materials were collected during the plant trials while an in-depth analysis on these materials was performed at the laboratory scale with certain explanations supported by the schematic and theoretical models. The work consists on different material classes such as steels and phosphor bronzes with a focus on the surface defects and their improvements. In order to facilitate the theoretical analysis which could be capable of explaining the suggested phenomenon in the thesis, a reduced model is developed which required lesser computational resources with lesser convergence problems.QC 20160527
Oscilation mark formation during continous casting of steel
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Bakir, Berna. "Defect Cause Modeling With Decision Tree And Regression Analysis: A Case Study In Casting Industry." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608427/index.pdf.
Повний текст джерелаАнотація:
In this thesis, we study improvement of product quality in manufacturing industry by identifying and optimizing influential process variables that cause defects on the items produced. Real data provided by a manufacturing company from the metal casting industry were studied. Two well-known approaches, logistic regression and decision trees, were used to model the relationship between process variables and defect types. The approaches used were compared.
14
Pelayo, Chagoya Graciela. "Development of a knowledge based system for the control of 319-Al melt quality and prediction of casting characteristics." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ62264.pdf.
Повний текст джерела
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Pinheiro, Carlos A. M. "Mould thermal response, billet surface quality and mould-flux behaviour in the continuous casting of steel billets with powder lubrification." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq27226.pdf.
Повний текст джерела
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Динник, Оксана Дмитрівна, Оксана Дмитриевна Дынник, Oksana Dmytrivna Dynnyk та А. Морщ. "Розробка методики оцінювання якості продукції ливарного виробництва". Thesis, Видавницто СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/20981.
Повний текст джерела
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Динник, Оксана Дмитрівна, Оксана Дмитриевна Дынник, Oksana Dmytrivna Dynnyk та І. Максименко. "Конструктивні і технологічні чинники формування якості продукції ливарного виробництва". Thesis, Видавницто СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/20948.
Повний текст джерела
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Bjurenstedt, Anton. "On the influence of imperfections on microstructure and properties of recycled Al-Si casting alloys." Doctoral thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH. Forskningsmiljö Material och tillverkning – Gjutning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-36963.
Повний текст джерелаАнотація:
There are great energy savings to be made by recycling aluminium; as little as 5% of the energy needed for primary aluminium production may be required. Striving to produce high quality aluminium castings requires knowledge of microstructural imperfections, which is extra important when casting recycled aluminium that generally contains higher levels of imperfections compared to primary aluminium. Imperfections include amongst others Si, Fe, and Mn as well as oxides. Si is needed for castability, but it may also initiate fracture. There are different types of Fe-rich intermetallics influencing properties of castings, generally in a negative direction. Oxides constitute cracks and they are elusive because they are difficult to quantify. This thesis aims to increase knowledge about imperfections in recycled aluminium castings originating from alloying elements and the melt. Experiments were performed in advanced laboratory equipment, including X-radiographic imaging during solidification and in-situ tensile testing in a scanning electron microscope. Experiments were also performed at industrial foundry facilities. The experiments showed that the nucleation temperature of primary α-Fe intermetallics increased with higher Fe, Mn, and Cr contents. Primary α-Fe are strongly suggested to nucleate on oxides and to grow in four basic morphologies. Lower nucleation frequency of α-Fe promoted faster growth and hopper crystals while higher nucleation frequency promoted slower growth rates and massive crystals. Results also showed that a decrease in the size of the eutectic Si and plate-like β-Fe intermetallics improved tensile properties, foremost the elongation to fracture. In β-Fe containing alloys the transversely oriented intermetallics initiated macrocracks that are potential fracture initiation sites. In alloys with primary α-Fe foremost clusters of intermetallics promoted macrocracks. In fatigue testing, a transition from β-Fe to α-Fe shifted the initiation sites from oxides and pores to the α-Fe, resulting in a decrease of fatigue strength. Oxides in Al-Si alloys continue to be elusive; no correlations between efforts to quantify the oxides and tensile properties could be observed.Genom att återvinna aluminium kan stora energibesparingar göras eftersom återvinning kan förbruka så lite som 5% av den energi som behövs för produktion av primär aluminium. Vid gjutning av högkvalitativa aluminiumprodukter krävs förståelse för defekter i mikrostrukturen och denna kunskap är extra viktig vid användning av återvunnen aluminium, som i regel innehåller mer defekter än primär aluminium. Defekterna består bland annat av Si, Fe och Mn samt oxider. Si behövs för gjutbarhet men kan också initiera brott. Järnrika intermetaller kan ha olika morfologier som generellt påverkar gjutna komponenter negativt. Oxider, som kan utgöra sprickor, är gäckande då de är svåra att kvantifiera. Denna avhandlings syfte är att öka kunskapen om defekter i gjutna komponenter av återvunnen aluminium. Experiment utfördes med avancerad laborationsutrustning så som röntgenfotografering av prover under stelning och dragprovning i svepelektronmikroskop. Experiment utfördes också i industrimiljö. Experimenten visade att kärnbildningstemperaturen steg för primära α-Fe intermetaller med ökade andelar av Fe, Mn och Cr. Resultaten tyder starkt på att primär α-Fe kärnbildas på oxider och att de växer i fyra olika morfologier. Lägre kärnbildningstäthet av α-Fe främjade snabbare tillväxt av kristaller med håligheter men högre kärnbildningstäthet främjade långsammare tillväxt av massiva kristaller. Resultaten visade också att minskad storlek av eutektiskt Si och β-Fe intermetaller ledde till förbättring av dragprovsresultaten, främst brottförlängningen. I legeringar med β-Fe ledde transversellt orienterade intermetaller till makrosprickor vilka kan initiera brott. I legeringar med primär α-Fe var det främst kluster av intermetaller som orsakade makrosprickor. I utmattningsprovning orsakade modifiering av β-Fe till α-Fe förflyttning av sprickinitieringen från oxider och porer till α-Fe, vilket resulterade i en reducerad utmattningshållfasthet. Oxiderna i Al-Si-legeringar fortsätter att gäcka; ingen korrelation mellan försök att kvantifiera oxiderna och draghållfasthet kunde påvisas.
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Abdalrahman, Khalid Haroun Mohamed [Verfasser], and Eckehard [Akademischer Betreuer] Specht. "Influence of water quality and kind of metal in the secondary cooling zone of casting process / Khalid Haroun Mohamed Abdalrahman. Betreuer: Eckehard Specht." Magdeburg : Universitätsbibliothek, 2012. http://d-nb.info/1053914369/34.
Повний текст джерела
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Abdalrahman, Khalid Haroun Mohamed Verfasser], and Eckehard [Akademischer Betreuer] [Specht. "Influence of water quality and kind of metal in the secondary cooling zone of casting process / Khalid Haroun Mohamed Abdalrahman. Betreuer: Eckehard Specht." Magdeburg : Universitätsbibliothek, 2012. http://nbn-resolving.de/urn:nbn:de:gbv:ma9:1-2685.
Повний текст джерела
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Ren, Qizheng. "The Application of Gage R&R Analysis in s Six Sigma Case of Improving and Optimizing an Automotive Die Casting Product’s Measurement System." TopSCHOLAR®, 2015. http://digitalcommons.wku.edu/theses/1536.
Повний текст джерелаАнотація:
With the rapid development of automation technology in automotive manufacturing processes, massive and efficient production is a current trend. Therefore, measurement systems with accurate and automated measuring instruments are sought by automotive companies and suppliers. However, the problematic measuring instruments with unreliable accuracy and stability lead to erroneous measurements and wrong quality decisions that cause manufacturers huge profit losses. An effective method called “measurement system analysis” can be applied to define and eliminate erroneous measurements to ensure adequate reliability. An automotive transmission die casting parts supplier called company T was suffering a serious profit loss due to the erroneous measurements from one type of their product’s measurement system. These erroneous measurements caused the company to deliver nonconforming products to their customers. The researcher conducted a study applying Six Sigma methodology to find out the root cause of the erroneous measurements and eliminate the erroneous measurements to retain adequate reliability. The researcher used DMAIC (Define, Measure, Analysis, Improve, and Control) process as framework to conduct the study and the measurement system analysis, Gage R&R method, to process several experiments for data collection and analysis. Through processing the experiments and analyzing the results, the researcher was able to detect the source of variation and find the root cause that caused the erroneous measurements. Based on the findings, the researcher then corrected the erroneous measurements and improved the problematic measurement system’s performance.
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Rozman, Jiří. "Nástroje jakosti pro hodnocení tlakově litých odlitků z Al slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230926.
Повний текст джерелаАнотація:
The goal of this diploma thesis is to on a practical example, with use of the quality system, describe the current state of input casting inspection in Tribotec Ltd. and output casting inspection of casting suppliers in this company and to suggest a new way of output casting inspection on Tribotec Ltd. with higher quality of spoilage rate survey of supplying casting already at the input inspection stage.
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Jaradeh, Majed. "The Effect of Processing Parameters and Alloy Composition on the Microstructure Formation and Quality of DC Cast Aluminium Alloys." Doctoral thesis, KTH, Materialvetenskap, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4205.
Повний текст джерелаАнотація:
The objective of this research is to increase the understanding of the solidification behaviour of some industrially important wrought aluminium alloys. The investigation methods range from direct investigations of as-cast ingots to laboratory-scale techniques in which ingot casting is simulated. The methods span from directional solidification at different cooling rates to more fundamental and controlled techniques such as DTA and DSC. The microstructure characteristics of the castings have been investigated by optical and Scanning Electron microscopy. Hardness tests were used to evaluate the mechanical properties. The effects of adding alloying elements to 3XXX and 6XXX aluminium alloys have been studied with special focus on the effects of Zn, Cu, Si and Ti. These elements influence the strength and corrosion properties, which are important for the performance of final components of these alloys. Solidification studies of 0-5wt% Zn additions to 3003 alloys showed that the most important effect on the microstructure was noticed at 2.5 wt% Zn, where the structure was fine, and the hardness had a maximum. Si addition to a level of about 2% gave a finer structure, having a relatively large fraction of eutectic structure, however, it also gave a long solidification interval. The addition of small amounts of Cu, 0.35 and 1.0 wt%, showed a beneficial effect on the hardness. Differences have been observed in the ingot surface microstructures of 6xxx billets with different Mg and Si ratios. Excess Si compositions showed a coarser grain structure and more precipitations with possible negative implications for surface defect formation during DC casting. The comparison of alloys of different Ti content showed that the addition of titanium to a level of about 0.15 wt% gave a coarser grain structure than alloys with a normal Ti content for grain refinement, i.e. < 0.02 wt%, although a better corrosion resistance can be obtained at higher Ti contents. The larger grain size results in crack sensitivity during DC casting. A macroscopic etching technique was developed, based on a NaOH solution, and used in inclusion assessment along DC cast billets. Good quantitative data with respect to the size and spatial distribution of inclusions were obtained. The results from studied billets reveal a decreasing number of inclusions going from bottom to top, and the presence of a ring-shaped distribution of a large number of small defects in the beginning of the casting. The present study shows how composition modifications, i.e. additions of certain amounts of alloying elements to the 3xxx and 6xxx Al alloys, significantly change the microstructures of the materials, its castability, and consequently its mechanical propertiesQC 20100901
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Abdullah, Eva. "Untersuchungen zwischen Belastungen und Belastbarkeiten beim Herstellen tongebundener Formen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-151086.
Повний текст джерелаАнотація:
Im Rahmen der vorliegenden Arbeit wurde versucht, Gesetzmäßigkeiten zwischen Kenngrößen aus dem Formstofflabor und einer praxisnahen kleintechnischen Formanlage abzuleiten. Der Zweck besteht darin, einen Fehler bei der Formherstellung (insbesondere Ballenabrisse) zu vermeiden. Dazu wurden zahlreiche Untersuchungen sowohl im Formstofflabor als auch an der Versuchsanlage vorgenommen. Dies gleicht in ihrer Funktionsweise betrieblichen Formanlagen mit unterschiedlichen Verdichtungsmöglichkeiten. Bei den Untersuchungen wurden Formstoffzusammensetzungen variiert, konstruktive Änderungen an der Formmaschine vorgenommen und die Formballen mit unterschiedlichen Formschrägen versehen. Zur Beurteilung der Gebrauchstauglichkeit einer Grünsandform müssen die Beanspruchbarkeiten größer als die entstehenden Beanspruchungen oder zumindest gleich sein. Dazu wurde eine neue Methode zur Bestimmung der Ballenabrissneigung unter Einsatz eines variablen Gießereimodells entwickelt. Durch eine zielgerichtete Kombination der an der Formherstellung beteiligten Komponenten: Formstoff, Formmaschine und Formprozess ließen sich qualitätsgerechte Formen herstellen und die Ergebnisse erfolgreich auf die betriebliche Praxis übertragen.
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Mercklé, Jean. "Stratégies de détection de rupture de modèle appliquées à la recherche et à la localisation des défauts sur des produits sidérurgiques." Nancy 1, 1988. http://www.theses.fr/1988NAN10047.
Повний текст джерелаАнотація:
Élaboration de deux stratégies de "détection-localisation" de défauts dans les signaux issus du contrôle par courants de Foulcault des produits sidérurgiques. Validation de ces stratégies dans le contrôle qualité de trois procédés : élaboration de brames de coulée continue, élaboration de blooms de coulée continue et de tubes
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Lin, Chih-Chiang, and 林志強. "The effect of recasting on the quality of pure titanium castings." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/67922730275809799574.
Повний текст джерелаАнотація:
碩士高雄醫學大學
牙醫學研究所碩士班
95
Objective: Molten titanium is highly reactive with common mold materials at elevated temperatures. There has been no paper published related to the recasting of pure titanium. It is probably due to the techniques for precise casting of pure titanium having yet to be developed perfectly. The aims of this investigation were to evaluate the possibility of casting the reused pure titanium by adding unreactive zirconia into the commercial magnesia-based investment material, and further more, to discuss the effects of recasting on the quality of pure titanium castings. Materials & Methods: According to the results of our previous study, an automatic argon-casting machine (Castmatic-S, Iwatani Co.), the trial investment: commercial magnesia-based investment (Selevest CB, Selec Co.) with 5% zirconia powder added, and the pure titanium ingots (CPT Dental titanium, Ohara Co.) were used to cast titanium castings. The initial casting used totally new pure titanium ingots. After casting, the surplus metal (sprue and button) removed from previous castings was carefully cleaned, weighed and combined with an appropriate amount of new ingots to maintain an approximate 50/50 ratio for the next use to produce the second castings. In this investigation, totally two groups were set and each group contained 5 casting MOD-inlay samples and 3 tensile bars. The success rate of complete casting was compared between two groups. The existence of internal porosity in these samples was evaluated with traditional dental x-ray machine. The average marginal discrepancy on a metal die was measured by 3D coordinate measuring machine. We also measured the average surface roughness of castings by surface roughness tester and the change of hardness from the surface to the center of the castings by microhardness tester. An x-ray diffractometer was used to evaluate the interfacial reactivity between the molten titanium and investment. The composition of castings was analyzed by EPMA and the tensile strength was tested by Instron. The data collected was analyzed with two sample t-test (p＜0.05); one-way ANOVA/ Tukey-Kramer HSD test (p＜0.05) and Pairwise correlations (p＜0.05). Result: The success rate of complete casting reached 100% in all groups. Little small internal porosity was found in both groups. The average marginal discrepancy and surface roughness showed no significant difference between two groups (p＞0.05). In hardness aspect, the VHN of initial casting samples and recasting ones all tended to decrease from the outer layer to the deeper part. And in both groups, an almost constant VHN, without significant difference, starting from the depth of 220μm down to the center was found. The results of XRD and EPMA analysis bothshowed the dominant component of recasting samples was still α-Ti. And the tensile strength of recasting samples was founded significantly higher than that of the initial ones (p＜0.05). Conclusion: Recasting of the pure titanium seems possible and workable. According to the result, we suggest grinding away at least 220μm thickness from the surface of the surplus metal used for repeated casting is necessary. It’s helpful in removing most of the reaction layer covering the samples. In this study, we recast the pure titanium just for one generation and chose the previous trial investment performing best to reduce the level of chemical reactivity. For understanding weather recasting through more than one generation and choosing different commercial investment materials and casting machines will lead to similar results to our study or not, more further investigations are required.
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Chen, J. S., and 陳建興. "On the Process Evaluation and Quality Control of the Production of A356 Wheel Castings." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/55179280884423431273.
Повний текст джерелаАнотація:
碩士國立臺灣大學
機械工程學系
85
abstract The production processes of A356 Al-wheels in a specific foundry was evaluated in this study. The process standardization was proposed for that specific foundry based upon the evaluation results. A rotary impeller degasser is currently used for the degassing treatment in the foundry. The degassed melt contained commercially accepted low gas level. However, the gas content of the melt increased gradually with increasing holding time, and the gas content reached an unacceptable level after holding for over 90 minutes. The microstructures of the Al-wheels currently produced in the foundry were thoroughly analyzed with the results indicating that substantial shrinkage porosity was present in the central portion of the rim section of the Al-wheels. Failing to maintain a directional solidification pattern and/or high enough temperature gradients were found to be responsible for the formation of the porosity defect. Modifying the ingate design and employing forced cooling at the central rim section were suggested for the elimination of this porosity defect. Furthermore, the feasibility of reducing the section thickness of the as-cast Al-wheels was evaluated in this study by using tensile and impact properties as the criteria. The results show that the original thickness of rim section of 10- 15㎜ can be reduced to around 9㎜. Also, accompanying with the reduction of section thickness, the T6 solution time at 540℃ can be shortened to 2-4hr from original 6hr and still obtains improved properties.
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Chen, Xiang-Yong, and 陳向詠. "The Application of CAE to the Riser Design of High Quality Furan Resin Mold Gray Cast Iron Castings." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/14780256317620260527.
Повний текст джерелаАнотація:
碩士逢甲大學
機械工程學所
91
The objective of this study is focus on the manufacturing of sound furan resin mold castings, by utilizing the foundry-use Computer Aided Engineering (CAE) technology to investigate the influence of riser design on furan resin mold casting. Both simulation and analysis will first be conducted, and then experimental results will also be adopted for comparison and validation. Besides, the hardness distribution of the castings will be tested, so we can know the influences of different riser designs on hardness distribution. The casting shapes are rectangular and circular and with dimensions of 300L×150W×50H mm and 240ψ×50H mm respectively. The pouring material is FC350 and uses the pressurized gating system. First, utilizing Chvorinov’s rule to design the initially riser. The parameter of design including the size and location of the riser. Then building the 3D model and run simulation on foundry-use CAE. At last, pouring all the different riser design castings and compare with the results of CAE simulation in order to investigate the feeding performance and yield of castings. So the technology on optimize the riser design of furan resin mold castings by using CAE simulation will be established. Besides, we choose the risers which are Modulusriser/Moduluscast=1 to do hardness distribution test on top plane and three different sections of the castings and then to investigate the influence of different riser designs on the hardness distribution of castings. The results of this study indicate that：(1)When we use top riser on furan resin mold castings and Modulusriser / Moduluscast>1, we can get sound castings. Using foundry-use CAE could raise the yield of the rectangular castings from 54.9% to 63.7% and the circular castings from 51% to 61%. (2) When we use side riser on furan resin mold castings and Modulusriser / Moduluscast>0.86, we can get sound castings. Using foundry-use CAE could raise the yield of the rectangular castings from 54.9% to 69.3% and the circular castings from 51% to 67.6%. (3)For rectangular castings, the yield of side riser design is 5.6% higher than top riser design. For circular castings, the yield of side riser design is 6.6% higher than top riser design. It means that side riser has better feeding performance and yield than top riser. (4)The regions of the castings that are far away from the riser have higher hardness and the regions that are close to the riser have lower hardness. (5)Top riser design castings have larger hardness variation than side riser design castings. (6)The regions that close to the gate have higher hardness because of higher cooling rate. Besides, set the side riser on the longer side(300 mm length side) of the rectangular castings will have better hardness distribution.
29
Polyakova, Irina. "Untersuchung der kognitiven Modellierung zur Gussstückqualitätsverbesserung." Doctoral thesis, 2012. https://tubaf.qucosa.de/id/qucosa%3A22898.
Повний текст джерелаАнотація:
Als Ergebnis der vorliegenden Arbeit wurde ein nützliches Hilfsmittel auf der Basis der kognitiven Herangehensweise zur Verbesserung der Effizienz der Managemententscheidungen für die Gussausschussverringerung und Qualitätsverbesserung in den Gießereien entwickelt. Das Werkzeug hilft dem Technologen, den Mechanismus des Gussfehlerentstehungsprozesses aufzudecken, die Logik der Gussfehlerentstehung zu verstehen und die präventiven Maßnahmen zu testen. Man kann das Werkzeug täglich im Betrieb benutzen, um die strategischen und operativen Entscheidungen rasch und ohne Durchführung der kostspieligen und komplizierten Versuche zu treffen. Auf diese Weise können Kosten und Zeit eingespart werden.
30
Lim, Tiong-wei, and 林長偉. "Quality evaluation of AZ91D recycling magnesium alloy in die-casting process." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/86721732930185342635.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
機械工程系
95
In general die casting factory, large volume of recycling AZ91D magnesium alloy materials were used. Although the recycled manufacturing supplier’s materials meet the standard norm, due to the difference of recycled material used the quality of the die casting parts was influenced widely and the understanding of the causes are limitedly. The main purpose of this research is to understand the influences of recycling AZ91D magnesium alloy to the mechanical property and corrosion resistance of the die casting parts. By choosing three existing reputed brand AZ91D material, to compare with own manufacturing magnesium alloy by using 100% pure magnesium, mixture of 30% pure magnesium with 70% recycling magnesium, mixture of 70% pure magnesium with 30% recycling magnesium, and 100% recycling magnesium. Different testing specimens are made by ingot without fabrication and by die-casting process. Through the analysis of chemical compositions, metallography, tensile strength test, impact test, hardness test and corrosion resistance testing, we try to clarify the characteristic of different combination of magnesium. From the analysis of a large number of test data, we realign that the main compositions like Al, Mn, Zn, Si, Fe, Ni, Cu, etc. which can influence the properties of the die-casting parts. Besides, the pollution of casting oxides, plunger lubrication oil and die release agents during die-casting process and the impurities of flux and residue during smelting are also influence the properties of the parts. To widen the use of all recycling AZ91D magnesium alloy can significantly reduce the manufacturing cost. The results detained in this study can be offered to the recycled material manufacturer and die casting factory for reference.
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Shen, Po-Chien, and 沈伯鍵. "An Investigation on Process Quality Improvement for Melt-Casting of Explosive." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/f4pt39.
Повний текст джерелаАнотація:
碩士義守大學
機械與自動化工程學系
107
At present, the production of large-calibre ammunition in military Arsenals is mainly based on the method of melt casting and pressing the explosives. The melt-casting shells must eliminate bubbles and porosity by probing process, and then it is solidified by the cooling process. The purpose of this study is to explore the best filling methods and equipments, and to improve the safety of production processes and equipment, so we can produce smoothly ammunition and reduce ammunition defects and critical factors in the production process. The Old equipment adopts single machine mode and manual operation. All operations that include equipment temperature changes and operating parameters are monitored by operators, which cause unstable process quality. Therefore, this study greatly reduce interference of the human factors and misjudgment and stabilize production quality by replacing the old production process and equipment upgrade, and monitor and set the operating parameters and temperature of the whole line by computer graphics control. At the same time, the equipment adopts the latest international explosion-proof standard IECEx（International Engineering Consortium for Explosive Atmospheres）Certification to improve the operators safety and reduce the risk of any accidents by explosives. This key point of study focuses on the probing depth. The study plans to use Composition B (RDX/TNT 60/40) as the melt-casting explosive and 105mm High Explosive Anti-Tank-Tracer (105mm HEAT-T) as a sample. First, we fix theequipment operating temperature and probing time data in the process of melting and filling. Second, we will study and test on the influence of the depth of the probing for the bubbles and the porosity on the inside of the projectile, and use X-ray to inspect the internal filling defects of the projectile. The result of the best probing depth setting is 75 mm.
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LEE, SANG-HUNG, and 李尚紘. "Combining Taguchi and DMAIC approaches to improve aluminum die-casting quality." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/87452695735679575096.
Повний текст джерелаАнотація:
碩士國立勤益科技大學
工業工程與管理系
101
The research will combine Taguchi and DMAIC approach, applies to Aluminum Casting so as to establish best parameters module, process improvement and reduce defects. First of all, Casting is the key target as set in order to increase profit and capability for competition as the company is looking for; secondly, we will apply Taguchi Method and combine 5 steps DMAIC of 6Sigma to improve casting process for product of Power Tools Industry than old fashion Try and Error so as to generate cost reduction, improve quality of product and capability for competition in the end. The result of experiment comes up Cpk value dramatically up to 1.89 was 0.11; porosity defect down to 4% was 34%; in terms of cost improvement, the cost saving from quality aspect, the cost saving was $231,000 before implementing the process ，and the cost saving was $1,155,000 after implementing the process. In other words, the best parameters identified through this study do improve the quality of aluminum die casting product.
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Wu, Chin-Chang, and 吳錦昌. "A Study of Centrifugal Casting Process Quality Improvement through Six Sigma Approach." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/37277196572016780928.
Повний текст джерелаАнотація:
碩士國立雲林科技大學
工業工程與管理研究所碩士班
100
Casting is the basic of traditional industries, the products widely applies in defense, medicine, steel, cement, petrochemical, electric power, shipbuilding, electronic, machinery, construction and so on. With the globalization of the competitive market, the casting already has been in the open international environment, with the newly-emerging nation develops fast, like the China and Southeast Asia where by the extremely low labor cost superiority caused the greatest impact on the domestic casting industry. The current important topic is how to promote the quality to reduce the cost in face the globalization of the competitive market. The casting divide into both normal and special that the centrifugal casting is one of special methods and can be saving-material, cost-effective. The research applies Six Sigma DMAIC methodology to improve the centrifugal casting process quality. First of all, we identified the critical quality characteristics and evaluate the measurement system, as well as find out the key factors which affect the process and will be optimize by the design of experiment. The result shows the defect rate was reduced 9.4%, effectively improve the process quality, and save production costs.
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Kao, Kai-Wei, and 高楷為. "Applying Quality Engineering Methods to Reduce Sand Inclusions in Investment Casting Industry." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/4q54p6.
Повний текст джерела
35
Yang, He-Kai, and 楊賀凱. "Supporting Quality of Service and Mobility Management of Media Casting over Wireless Networks." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/22416354018316039251.
Повний текст джерелаАнотація:
碩士國立臺灣大學
資訊管理學研究所
94
With the widely deployed wireless networks, people have another choice to access the Internet. Therefore, many applications originally provided on wired networks will be used over wireless environment, and multimedia services may be the most popular one in the near future. Delivering multimedia content via multicast in our system saves unnecessary bandwidth wastage and uses limited wireless resource more efficiently. Besides, we compress video content through the adaptive mechanism─scalable video coding according to the video quality users need. However, nodes in wireless networks move anytime and multimedia services may disconnect during handoff, mobility management issues must be considered when providing seamless services. Moreover, real-time applications are sensitive to delay and jitter, Quality of Service (QoS) guarantee need to be provided. We propose “pre-download” scheme in order to pre-construct multicast tree, then MN will not suffer from delay and could always get basic quality content during handoff. Besides, our most important contribution is to design “preemption” scheme. Through the flexibility provided by scalable video coding, we let handoff MN preempt others’ high quality enhancement layer (EL) stream to continually download basic quality content when system resource insufficient. Therefore, we not only favor handoff MN than new arrival one to keep handoff dropping probability low but also utilize the channel. In the end, we propose concept of Full quality Utilization (FU) on admission control unit to manage the resource adaptively. We evaluate both our mobility management scheme and MAC mechanism used to provide QoS on AP (IEEE 802.11e MAC). In the simulation results, our scheme outperforms previous work favor handoff MN by bandwidth reservation on three important performance metrics : utilization、new blocking probability and handoff dropping probability.
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Farahani, Alavi Forouzandeh. "In-line Extrusion Monitoring and Product Quality." Thesis, 2010. http://hdl.handle.net/1807/29967.
Повний текст джерелаАнотація:
Defects in polyethylene film are often caused by contaminant particles in the polymer melt. In this research, particle properties obtainable from in-line melt monitoring, combined with processing information, are used to predict film defect properties.
“Model” particles (solid and hollow glass microspheres, aluminum powder, ceramic microspheres, glass fibers, wood particles, and cross-linked polyethylene) were injected into low-density polyethylene extruder feed. Defects resulted when the polyethylene containing particles was extruded through a film die and stretched by a take-up roller as it cooled to form films 57 to 241mm in thickness.
Two off-line analysis methods were further developed and applied to the defects: polarized light imaging and interferometric imaging. Polarized light showed residual stresses in the film caused by the particle as well as properties of the embedded particle. Interferometry enabled measures of the film distortion, notably defect volume. From the images, only three attributes were required for mathematical modeling: particle area, defect area, and defect volume. These attributes yielded two ”primary defect properties”: average defect height and magnification (of particle area). For all spherical particles, empirical correlations of these properties were obtained for each of the two major types of defects that emerged: high average height and low average height defects. Analysis of data for non-spherical particles was limited to showing how, in some cases, their data differed from the spherical particle correlations.
To help explain empirical correlations of the primary defect properties with film thickness, a simple model was proposed and found to be supported by the high average height defect data: the “constant defect volume per unit particle area” model. It assumes that the product of average defect height and magnification is a constant for all film thicknesses.
A numerical example illustrates how the methodology developed in this work can be used as a starting point for predicting film defect properties in industrial systems. A limitation is that each prediction yields two pairs of primary defect property values, one pair for each defect type. If it is necessary to identify the dominant type, then measurement of a length dimension of sufficient defects in the film is required.
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Kumar, Sunil. "An expert system to diagnose quality problems in the continuous casting of steel billets." Thesis, 1991. http://hdl.handle.net/2429/1671.
Повний текст джерелаАнотація:
Quality problems, such as cracks, rhomboidity and breakouts are often observed in continuously cast steel billets. Although information is available in the literature on the causes of, and solutions to, these problems, the transfer of this knowledge to operating personnel is not always an easy task. To address this issue, an expert system has been developed.
The important features of knowledge engineering an expert system to diagnose quality problems in the continuous casting of steel billets are described in this thesis. The process used to extract knowledge from the Experts, the experiments employed to represent knowledge indifferent ways, the strategies adopted to accumulate evidence and the methodologies to present coherent recommendations to both experienced and inexperienced operating personnel are discussed.
Expertise was derived from diverse sources. On the one hand fundamental knowledge about heat transfer, solidification and mechanical behaviour of steel was applied to identify the origin of a quality problem in the process; on the other, heuristic knowledge associated with billet characteristics, machine design and operating factors was required to focus on the problem causes. Integration of these two different types of knowledge was essential in developing a useful system.
From the Experts' viewpoint, this exercise provided them with a formal representation of their knowledge to solve quality problems and identified new areas for future research. Moreover, the Experts actually generated new ideas about the domain which previously were unrecognized. For the users, this system serves two important functions - as a diagnostic tool for analyzing quality problems and as a teaching tool for new operating personnel.
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Lungu, Chozi Vincent. "Sustainable production of quality bronze alloy bearings in under-resourced small scale casting facilities." Thesis, 2020. https://hdl.handle.net/10539/31286.
Повний текст джерелаАнотація:
A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy, 2020There are good reasons to keep the local economy of the Copper belt in Zambia growing. Mining consumables and spares that can be manufactured locally such as bronze sleeve bearings is one way of doing so and can benefit local people a great deal. Bronze sleeve bearings of a fit for purpose quality can to a large extent be cast in a small under-resourced foundry (SURF) sustainably. Sustainability implies survival requiring both consistency of output and cost effective selection and use of secondary materials and aiming for products suited to the market. There is therefore a combination of both technical and economic or business questions. The research examined challenges encountered in a typical SURF and sought to offer a solution for cost effectively producing near net size finished bronze sleeve bearings of a composition that achieves the required mechanical properties to replace directly machined varieties. It was aimed therefore to produce fit for purpose sleeve bearing that represented value for money and were cost effective. Within this thesis focus was on one selected candidate bronze foundry, Fox Foundry, situated in Kitwe on the Copper belt of Zambia. To establish the fit for purpose standard, the methodology employed sampling of used bronze bearings considered successful in service from producers and various users. These were tested for chemical, mechanical and metallurgical properties. Experimental castings were made using a permanent mould at Heroes Foundry and the University of Johannesburg. Factors examined for the experimental castings were; temperature, composition, feeding, pouring and mass. A matrix design approach was also employed to optimise on the number of experimental runs required as opposed to using conventional factorial method. The resulting microstructure from each experimental cast was the response variable determined. Test results of the bronze bearings considered successful in service (or OEM) showed irregular microstructure, inconsistent mechanical properties and unacceptable porosity levels. Chemical composition results indicated no control on levels of alloying elements and that had an impact on microstructure and properties dependent on it. Results from experimental castings on the other hand showed that a consistent and optimal microstructure was key in producing a successful bearing as it was the basis of all secondary properties. It can be concluded that a SURF such as Fox Foundry of Kitwe can successfully produce near net sleeve bearing requiring little or no machining providing basic elements of quality in materials and processes are adhered to during production. Whilst SURFs have a low fixed capital base the costs of energy use and metal procurement are an important contributor to competitiveness and should be monitored carefully.. A training programme developed for a typical SURF which when implemented can complement the important measures of material and process quality control and energy conservation to ensure a first time casting fit for purpose ivThe work undertaken in here is dedicated to enterprises and individuals serving in the foundry sector particularly in Zambia contributing tirelessly to improving local economic conditions where they are based.
CK2021
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Weijia, Shi, and 施韋嘉. "A Study of Machining Dimension Stability and Casting Defects with Quality Control and Analysis." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/65194510524823018245.
Повний текст джерелаАнотація:
碩士中州科技大學
機械與自動化工程系
103
Abstract In recent years, fraction defective rate of machining company casting products can be broadly divided into three types, (1) castings (2) tool wear (3) poor processing, resulting in defective products. Tangible losses such as heavy industry, painting, renewal or even scrapped and intangible losses that must spend a higher cost with the company. Also delayed delivery will decrease the credibility of the company. In order to enhance and improve the company's casting and machining production quality and efficiency. Studied and analyzed the reasons of defective products by researcher’s machining company on quality control currently. Investigating the company's casting products by statistical analysis could observe improvement measures of the production of castings. The manufacturing process with a variety of test problems caused by bad itemized proposes possible improvement measures. The implementation of the pursuit of quality spirit expected the product is good quality enough, that enhance the company's external competitiveness. The main conclusions of this study are as follows: (1) Casting their possible causes are hard spots, sand holes, lack of materials and crack defects. (2) Tool wear and tear can be caused by fracture and wear. (3) Machining workpiece can be caused by over-cutting and impact. (4) Process capability of horizontal machine processing were higher than the capability of the vertical machine. (5) Process capability of night shift staffs is higher than the ability of process the day shift personnel. Keywords: Machining Dimension Stability, Casting Defects, Quality Control and Analysis
40
Chien, Chuan-kuo, and 錢傳國. "Building of a Quality System for the Casting Industry:the case of A Mechanical Company." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/65458148022136186362.
Повний текст джерелаАнотація:
碩士國立高雄大學
高階法律暨管理碩士在職專班(EMLBA)
100
Casting industry is called 3K industry in Taiwan because its work circumstance with the potential danger : kitsui、kitanai and kiken (in Japaness) etc. What is the direct way to improve the work circumstance and uncertain quality is that building up a set of good system for improvement and standard flow. Making use of standard flow prevents and improves the potential danger of work circumstance to standardize the process and increase the product quality. Taiwan manufacturing level obtains a good evaluation from the international, specially mechanical equipment. In order to satisfy the customer requirement and maintain the competitiveness, constant improvement is essential for Work hour Reduction, Standard production system and Quality stability advance. This research, consists Quality Program of Machinery Enterprise Company Building of Tainan Taiwan, Fusion MIL-Q-9858A(U.S.A MILITARY SPECTFICATION) Quality Program, MIL-STD-45662 Quality Program, ISO 9001:2008 Quality Program, provides standard flow to Organization operation, Standard for production flow, competitiveness to production quality, and provides the requirement for Domestic and foreign nation armament, Ships component and mechanical equipment process. It takes the huge expense on Building Quality system for Casting industrial. This research takes the case of Building Quality system of A machine corporation(casting), to share with same area of company(casting) and the others for reference to achieve the effect of “To yield twice the result with half the effort” and system building economization.
41
Chiao, Tsai-Meng, and 蔡孟樵. "The Effect of Dispersion and Defoaming-use Surfactant on the Various Properties of Coating and Casting Surface Quality for the Evaporative Pattern Casting Process." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/62245164386069421779.
Повний текст джерелаАнотація:
碩士逢甲大學
機械工程學所
99
Evaporative Pattern Casting process is a special method of casting. In this process, the coating properties (permeability, adhensive property, crack resistance, erosion resistance, foaming property, and settlement property), have a significant affect on casting surface quality. The objective of this research is to investigate the effect on the coating properties and casting surface quality of adding dispersion-use and deforming-use surfactant to the coating. Firstly, to adopt the coating without surfactant addition (Type1) to investigate the various properties (permeability, adhensive property, crack resistance, erosion resistance, foaming property, and settlement property), and regarded as the comparsion basis for experiment follows. Secondly, by adding different proportions dispersion-use surfactant (0.5%, 1%, 2%, 3%, 4%, 5%), (Type 2 ~ Type 7)to the coating, and to investigate the effect on the coating properties. Thirdly, to use a fixed percentage of dispersion-use surfactants (1%) then they were added with different proportions of deforming-use surfactants (0.01%, 0.02%, 0.03%), (Type 8 ~ Type10), and also to investigate the effect on the coating properties. Finally, by using the previous three type coatings to the actual pouring, and to find the effect of coating types on the surface quality of aluminum alloy casting. The experiment results show that coatings with dispersion-use surfactant have better settlement property and permeability compared to the coatings without surfactant, but have the same crack resistance、erosion resistance、adhensive property ,foaming property. It is regarded as the result of bubble forming effect by the dispersion-use surfactant. Coatings with fixed (1%) dispersion-use surfactant but with different defoaming-use surfactant are compared with coating without surfactant (Type1). When the defoaming-use surfactant increased, the permeability、erosion resistance、settlement property、surface quality became better. Moreover when compared with coatings only with dispersion-use surfactant(Type2~Type7), the erosion resistance、adhensive property、foaming property、surface quality were better. Therefore, the above experiment results show that, coating (Type10) with defoaming-use surfactant (0.03%) and dispersion-use surfactant (1%) is the best coating one .
42
Huang, Jong-Yu, and 黃炯瑜. "The Effects of Casting Condition on the Dimensional Accuracy and Surface Quality of EPC Process." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/20318581515401146877.
Повний текст джерелаАнотація:
碩士逢甲大學
機械工程研究所
85
ABSTRACT The shape design, making condition , and casting condition etc., of the pattern used in the EPC process, will affect the quality and dimensional accuracy of the casting after poured. So that how to control and how to make the pattern to have the various good characteristics, and how to control the casting condition, in order that the castings have good quality and dimension accuracy after poured, is a very important thing. This study is to probe into the relationships among the shape design and making condition of pattern, the casting condition, and the surface quality and dimensional accuracy of casting. By using the self-designed and manufactured metal dies to produce patterns. And the casting ccoating, vibration time, vacuum degree, pouring temperature, etc. Finally, the onditions include thickness of dimensional accuracy of castings such as surface roughness, surface quality, dimensional accuracy, is concerned. Then we can establish the data base of the optizimed pattern shape design and condition of pattern making, and the casting condition of the castings with good quality. According to the experiment, it is concluded that when the pattern bead is B type, vibration time is longer, vacuum degree is medium, pouring temperature is lower, the casting after poured have better surface quality. When the pattern bead is B type, coating thickness is thicker, vibration time, vacuum degree, pouring temperature are lower, the casting after poured have better dimensional accuracy. When the pattern bead is B type, coating thickness is medium, vacuum degree is higher, vibration time, pouring temperature are lower, the casting after poured have better surface roughness. Keywords: EPC process, Shape design, Pattern making condition, Casting condition, Surface quality, Dimensional accuracy, Surface roughness
43
Bouhouche, Salah [Verfasser]. "Contribution to quality and process optimisation in continuous casting using mathematical modelling / vorgelegt von Salah Bouhouche." 2002. http://d-nb.info/966041208/34.
Повний текст джерела
44
Meenken, Thomas. "Analysis of the cooling capacity of water as a function of its quality during DC casting." Thèse, 2003. http://constellation.uqac.ca/750/1/17771752.pdf.
Повний текст джерелаАнотація:
As in many thermal processing technologies, there is a delicate balance between productivity and quality during ingot cooling process. Higher cooling velocities increase productivity but also create higher temperature gradients inside the ingot. Such a fast cooling does not leave sufficient time to establish the equilibrium within the solid, thus in the most affected surface layer the composition and crystalline structure are different from those in the bulk metal. The heat flux plays a particular role for the production of alloys where different melting points and complex structure formation -depending on the temperature- are present. To prevent the two worst cases - cracking and remelting - during cooling a balance has to be found between good productivity and quality on the one side but also a high security on the other side. To avoid the negative effects of cracking and remelting, it is necessary to determine the heat flux as a function of the influencing parameters and to control the cooling in order to obtain a maximal productivity with the required quality. There is no widely accepted method for the quantitative characterization of the cooling capacity of the water. The cooling may be characterized by the heat transfer coefficients measured in different boiling regimes on the surface or directly by the heat flux. As the fluid flow and heat transfer phenomena are very complicate in the falling liquid-vapour film, using the heat transfer coefficients does not necessarily help the understanding of the underlying mechanisms. However, the correlation between the surface heat flux and temperature for a given surface roughness and water quality includes all the relevant information about the cooling process. Thus in the present project our main objective was to determine the surface heat flux for a water cooled ingot as a function of the water quality in order to provide a tool for assuring a uniform quality in the cast-shop. A further objective was to improve the understanding of the flow of boiling liquid film along a solid surface. The first challenge in the project was the development of a surface temperature and heat flux measurement method which does not disturb the ingot surface. A heat flux sensor attached onto the surface would have negative effects on the film-nucleate boiling process and increase the surface roughness that affects the nucleation of bubbles. Furthermore it was important that the measurement method be fast responding and sensitive enough to detect very rapid and weak variations in the surface temperature. Thus an innovative surface temperature sensing method - using an open-tip thermocouple - was developed. This sensor was inserted into a null-point cavity from the backside of the aluminium ingot. The open-tip sensor combined with the null-point cavity forms a null-point calorimeter. Using the inverse solution of the general heat conduction equation, it is possible to determine the surface heat flux from the measured temperature history. For the analytical solution of the heat conduction equation in one dimension we used the so called Cook-Felderman equation. It was also investigated how well the assumptions of the Cook-Felderman equation are applicable to the actual conditions in our experimental setup. For this purpose a computer program was developed. The algorithm uses the finite volume approach; the program was written in C++ and calculates the transient 2D temperature distribution in the solid sample. The two-dimensional model uses the measured temperature histories as boundary conditions. The computer predictions were used to determine the horizontal and the vertical heat flux components during the cooling process. Furthermore it was analyzed how the heat flux results obtained analytically by the Cook-Felderman equation compare to the more detailed numerical solutions. The cooling process is strongly influenced by the different water types and different ingot surfaces. Thus the investigations were focused on the difference between several water types such as tap water (conductivity: 90fiS), plant water (conductivity: 1900/uS') and water with higher conductivity (conductivity: 3200/uS). These water types were tested on different ingot surfaces to eliminate the influence of the surface structure. In addition, the effects of some water additives and a water-oil mixture on the surface heat flux were investigated. The surface temperature measurements were accompanied by a visualization of the surface boiling effects. Furthermore the difference between different ingot surfaces was analyzed. The tests made on machined and a rough surface ingots provided information about the differences in the temperature cooling curves as well as information about the structure of the cooling water film. All collected measurement and visualization data were analyzed to explain the surface flow and boiling effects during the cooling process. The dynamic structure of the falling water film was investigated. Certain characteristics in the temperature cooling curves can be explained with the structure of the water film. We achieved a very good experimental repeatability. We found that the repeatability of the boiling phenomena itself depends on the measurement position (height along the ingot). It was observed that there are more fluctuations on a machined ingot than on a rough surface ingot. Even two different rough plates have different heat flux results. The tests using different water types have shown that there is almost no difference between tap and plant water, neither on a machined nor on a rough ingot. A difference could only be found between tap water and high conductivity water.
45
Li, Cheng-Lung, and 李正隆. "The Quality Change Of Molten Aluminum Alloy After Flowing Through The Ceramic Foam Filter In Gravity Casting." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/35553263310024679491.
Повний текст джерелаАнотація:
碩士國立聯合大學
材料科學工程學系碩士班
101
Ceramic foam filter is normally applied in the design of runner system in aluminum gravity casting. The purpose of using this filter is to reduce the velocity of liquid aluminum under the so-called critical gating velocity (e.g., 0.5 m/s for aluminum alloys). After liquid aluminum flows through the foam filter, its static pressure energy is recovered from kinetic energy. The foam filter then can be used for stabilizing the aluminum flow during the filling of mold cavity. The so-called bi-film defect, deriving from the surface turbulence and the entrapment of oxide films during filling process, can thus be avoided. The purpose of this study was to understand the change of profile and melt quality of liquid aluminum after flowing through the foam filter in various runner system designs. Three types of bottom gating runner systems were designed. For observing the flow going through the ceramic foam filter, water analogy method, dyed water filling test in a transparent PMMA material mold, was applied. This flowing profile had been used for the validating the result of computational modeling. In the casting experiment, the aluminum casting sample in the outlet region of the foam filter was sectioned. These specimens then did re-re-melt reduced pressure test (re-melt RPT). The bulk density of the specimens was measured by Archimedes method. By comparing the density differences between the original degassed liquid aluminum and the casting specimens, the contamination of hydrogen of the liquid aluminum after flowing through the filter was measured. "Area normalized" Bifilm index map was proposed to quantify the content of bifilm defects within the casting samples.
46
Wu, Tsung-Yen, and 吳宗諺. "The Effects of Casting Parameter of the In-mold Process on the Quality of Ductile Cast Iron." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/41600212990785076011.
Повний текст джерелаАнотація:
碩士逢甲大學
機械工程學所
94
The objective of this research is to focus on the manufacturing of furan resin mold ductile cast iron by using the In-mold Process. Casting parameters (addition amount and grain size of nodulant, pouring temperature, the use of cloth filter etc.,) on the mechanical properties (tensile strength , elongation , hardness , impact value etc.,) and metallographic microstructures (nodularity, count of nodule , matrix etc.,) of the ductile cast iron were investigated in this research. The results of this study indicate that ： (1) when the addition amount of nodulant is 1.0wt%, the tensile strength is the best 500MPa . When the addition amounts of nodulant are 0.9wt% and 0.8wt%, the tensile strength decreases to 403 MPa and 358 MPa, respectively. The results of tensile strength variation are matched with the metallographic microstructrure results of nodularity and matrix. (2) The grain sizes of nodulant are coarse (>6.35mm), medium (5.66~6.35mm), fine (<5.66mm). With the coarse type, the nodulant can not melt fully；and with the fine type, the molten iron can not enter to the reaction chamer sufficiently；therefore using the medium type of nodulant can obtain the best casting quality. (3) When the pouring temperature is 1500℃, the tensile strength of casting is better than the other two pouring temperature (1470,1440℃). (4) The mechanical properties of using the cloth filter are better than without cloth filter. (5) When the addition amount of nodulant is 1.0wt% and the grain sizes of nodulant are medium (5.66~6.35mm) and the pouring temperature is 1500℃ , the impact value is lowest . (6) When the addition amount of nodulant is 1.0wt% and the grain sizes of nodulant are medium (5.66~6.35mm) and the pouring temperature is 1500℃, the hardness is highest .
47
Cho, Wang-tzu, and 卓琬姿. "Improving the Process Quality of Investment Casting Industry via Six Sigma－A Case Study of B Company." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/666m6z.
Повний текст джерелаАнотація:
碩士國立雲林科技大學
工業工程與管理系
103
Chinese's manufacturing sector, the most important competition in the market, subject to the same competition, in order to break through price competition, improve product quality and highest priority, therefore, the importance of the quality of attention. Business managers can no longer be past the old norms to judge the quality problem, you should have to face up to the current quality problems, introducing appropriate improvement methods. With the advancement of technology faces major companies, the relative quality of the process followed to enhance, reduce product defect rate has become valued by many businesses. There are good and stable quality control process, product defect rate will therefore reduce, you can really meet customer demand and reduce the company's production costs. In order to get the best quality, enterprises should select the most appropriate quality management system tools to assist businesses stable quality, streamline processes, improve efficiency and reduce the cost of the optimal strategy. And promote Six Sigma, it is to obtain one of the best quality management system tools. By pushing Six Sigma, to achieve enterprise restructuring physique, improve profitability, enhance the quality of the best state. In this study, the case of traditional lost-wax casting industry company B as the main object of study, and to collect the relevant literature, the application of Six Sigma improvement techniques to improve the quality of our products problem cases of sand hole defect rate, in order to improve customer satisfaction, reduce product defect rate and save production costs. The results showed that the use of Six Sigma quality improvement techniques and with the SOP and experimental design, which can effectively reduce product defect rate, 21.38% rate of improvement before adverse reduced to 5.4%, reduced scrap and rework costs by the monthly average of 1.07 million to 430 000, Sigma index increased from 2.3 to 3.1; case if the company continued to apply six Sigma DMAIC approach to improve the overall quality of the process, will enhance the company's competitiveness and cost savings. Keywords: Six Sigma, Investment Casting, defection rate, DOE
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Lee, Gumn-Ben, and 李冠伻. "The Influence of Furan's Molding Parameters to the Properties of Mold and the Quality of the Casting." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/70601773757709248212.
Повний текст джерелаАнотація:
碩士國立臺灣師範大學
工業教育研究所
88
Abstract The continuous discovery of new materials and methods has brought about a lot of change in the foundry industry. For instance, the emerging of the Furan No Bake process has gradually not only become the principal method for large-sized castings, but also been accepted extensively in the foundry industry with its characteristics of convenience and cleanliness. In the purposes of finding out the best combination of new sand and reclamation sand, and then reaching the demand of the most economical making process and the best quality for casting, this experiment has attempted to discuss some property changes of Furan No Bake process, such as the influence of mold hardn- Ess, dry compression, dry shear, surface stability, permeability , grainfineness, LOI and so on. Furthermore, by using the ladder molding, pouring gray cast iron and nodular graphite cast iron, the surface quality of casting and micrograph in ladders have been analyzed. Also, with different cooling temperatures being put on ladders, we could acquire the needed information about hardness. The conclusions of the experiment are as follows: The kind of Furan sand uses 100% new sand, 50% new sand plus 50% reclamation sand, 50% reclamation sand. Furan resin uses 0.5%, 1.0%, 1.5% in FNB process, and the time to hardness is set to 60 mins. Uses 1.5% Furan resin. The 100% new sand is the best for hardness, surface stability and permeability, when 1.5% Furan resin is used getting the larger hardness 70. when 1.5% Furan resin is used getting the smaller surface stability 6.54%, when 0.5% Furan resin is used getting the best permeability is 719. When 1.5% Furan resin is used, getting large dry compr- ession of 50% new sand plus 50% reclamation sand. The value is 1.28Mpa. Because the 100% reclamation sand remains the fronter hardness surface, in 60% furan resin, the value of the grain finess is 15.73. The largest value of the L.O.I. is 1.3%, and of the shear is 0.224MPa. The surface quality of casting is best with the combination of 50% new sand, 50% reclamation sand and 1.5% of the furn binder, along with being pouring from the thin ladders. Pouring height uses above 30cm location with many gas holes on the surface. The micrograph of gray cast iron turns out to type C graphite, and type B graphite in thick ladders and thin ones, respectively. The graphite diverges are evenly from the thick ladders and the thin ones’ micrograph are dendrite. The nodularity rating and the nodule count of nodular graphite cast iron are represented in the thin ladders, whcih are higher than those are visible in the thick ones.The micrograph in the thin ladders contains much more Pearlite as well. The hardness of the thin ladders casting is larger than thick ones. The Brinell Hardness Number for thick ladders of gray cast iron is HB105 in average; whereas for thin ladders is HB108 in average. The hardness for thick of nodular graphite cast iron is HB81 in average; whereas for thin is HB87 in average. The Brinell Hardness Number for gray cast iron at thicker side of ladders is larger, HB107.in average.The hardness for gray cast iron, the thinner side is larger on reversed side, HB109 in average. The Brinell Hardness Number for nodular graphite cast iron, reversed side is larger, HB82 in average.The hardness for nodular graphite cast iron, reversed side is larger, HB88 in average.
49
Camisani-Calzolari, Ferdinando Roux. "Quality prediction and control of continuously cast slabs." Thesis, 2003. http://hdl.handle.net/2263/24938.
Повний текст джерелаАнотація:
Please read the abstract (Summary) in the section, 00front of this documentThesis (PhD (Electronic Engineering))--University of Pretoria, 2008.
Electrical, Electronic and Computer Engineering
PhD
unrestricted
50
Pinheiro, Carlos A. M. "Mould thermal response, billet surface quality and mould-flux behaviour in the continuous casting of steel billets with powder lubrication." Thesis, 1997. http://hdl.handle.net/2429/8560.
Повний текст джерелаАнотація:
The main objectives of this study were to examine mould thermal response and billet
surface quality during continuous casting of steel billets with powder lubrication, and to
compare with oil lubrication. Measurements were carried out on an operating billet caster to
determine mould-wall temperature profiles for different mould-flux types, mould coolingwater
velocity, oscillation frequency and steel grade. The trial involved data acquisition on
mould displacement, casting speed, metal level and mould powder temperature field. In
addition, mould powder consumption and liquid flux pool depth were also measured.
An inverse heat conduction model was developed to determine mould heat flux from
measured mould wall temperatures. Existing mathematical models were utilized to investigate
mould/billet binding and mould taper. Results from plant measurement, mathematical models
and billet sample evaluation were used to compare mould-powder and oil casting in terms of
mould thermal response, transverse depression, rhomboidity, oscillation mark and mould level
variation. Finally, a mathematical model was developed to analyze the influence of mould-flux
properties and feeding strategies on melting behaviour.
This work has led to a very comprehensive understanding of mould thermal response and
mould-related quality problem in billet casting with powder lubrication. Transverse
depressions were found to be formed in steel grades with high coherency temperature due to
metal level fluctuation. For Boron(Ti)-alloyed medium-carbon steel cast with powder
transverse depressions were eliminated due to a substantial decrease in meniscus heat flux,
thus producing a thinner, hotter, more flexible shell, and also due to lower metal level
fluctuations on account of pouring with SEN. An understanding of the role of titanium and nitrogen on transverse depressions resulted in
the establishment of maximum values for these elements. In order to minimize transverse
depression in billet casting with oil lubrication the nitrogen content of the steel must be kept
below 60 ppm and the titanium content below 0.019%.
Mathematical modelling of billet shrinkage, corroborated by billet inspection, showed that
excessive mould taper caused the mould to squeeze the solidifying shell which led to the
formation of longitudinal depressions. To eliminate this problem a double mould taper with
1.8% m⁻¹ up to 450 mm from the mould top and 0.9% m⁻¹ for the rest of the mould is
recommended. Mathematical modelling of mould powder melting has led to further
understanding of the response of the molten-flux pool to changes in powder properties,
feeding strategies and casting speed.