Dissertations / Theses on the topic 'Grinding -Alloys'
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1
Wang, S. H. "Investigation into the grinding of titanium alloys." Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/10569.
Full textAbstract:
Titanium
alloys are used extensively in the aerospace industry due to their
high specific strength and excellent corrosion resistance. However, their poor
thermal
conductivity and high chemical reactivity with tool materials make the
machining difficult, especially when grinding. During grinding, the excessive
heat generated at the wheel-work piece interface may result in poor surface
finisil,1_, a transformed surface layer, excessive plastic deformation, thermallyinduced
residual tensile stress, burn and micro-cracking on the ground
surface. The
poor surface integrity and metallurgical changes of the surface
and sub-surface
may impair the surface sensitive properties such as fatigue
life
during service.
ln order to overcome the thermal
problems when grinding titanium alloys, a
new
cooling strategy, cryogenic grinding, was studied which involves the
supply of liquid nitrogen into the grinding zone using a nozzle jet system. lt
was found that
cryo-cooling with conventional grinding wheel decreased
surface
roughness values, burn and plastic deformation of Ti-6Al-4V alloys
and
produced better a cutting mechanism than when using water-based
coolant, especially at higher depths of cut. However, the thermal problems
still introduced
high residual tensile stress which degraded the fatigue life of
ground specimens. Another approach to reducing the grinding temperature
was to use a
superabrasive wheel (diamond), because of its superior thermal
conductivity, the integrity of the ground surface was improved and the fatigue
life
properties of the specimen were maintained at higher values than for
conventional
grinding wheels.
An ultra stiff machine tool, Tetraform C, was also used to grind Ti-6Al-4V
alloys and under selected conditions the ground surface reached a good
surface finish and the
fatigue properties were also retained at lower depth of
cut. An ELID
system on the Tetraform C was also investigated. It produced a
rougher surface finish in this study. However, it is believed that reducing the
wheel
loading problem when grinding titanium alloys may contribute to
maintaining the fatigue properties.
2
Setti, Dinesh. "Performance improvement in grinding of Ti-6Al-4V alloy and modeling of surface roughness." Thesis, IIT Delhi, 2016. http://localhost:8080/iit/handle/2074/7069.
Full text
3
Shiue, Ren-Kae. "Active braze alloys for metal single layer grinding technology." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/86277.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 1996.Vita. Cataloged from PDF version of thesis.
Includes bibliographical references (pages 144-153).
Components made of high-performance ceramics or superalloys are subject to strict requirements with regard to their geometric and dimensional accuracy. The surface finish and edge zone characteristics have a large effect on the component's performance. These requirements can not be met directly by the sintering process used in the manufacture of ceramic materials or traditional casting of superalloys. Grinding is both technically and economically the number one choice when one has to consider machining these materials. Metal Single Layer (MSL) grinding technology provides an alternative way to make use of the superabrasives, diamond and CBN, in grinding these materials. One of the primary challenges in MSL grinding technology is to develop suitable active braze alloy(s) which can bond the superabrasive grits. Ticusil (Ag-Cu eutectic+4.5 wt% Ti) and 70Cu-21Sn- 9Ti (wt%) are two of the currently used active braze alloys. The primary failure mode of these two MSL wheels in the grinding test is transverse fracture and debonding of the diamond grits. The high applied load is responsible for transverse fracture of the diamond grit, and the intermetallic phase existing at the interface between the diamond and the braze alloy is one of the causes of the debonding of the diamond grits. Also, a finite element analysis shows that most of the residual thermal stresses and the thermal mismatch strains are localized at the diamond/braze alloy interface. This results in potential weakness of this area. Moreover, the inherent defects, such as voids, and the brittle intermetallics in the interface can cause crack initiation and propagation. Both deteriorate the life of the grinding wheel. The failure of the braze alloy can be divided into two categories. If the grinding process is very abrasive, such as green concrete grinding, the wear resistance of the braze dominates the fracture of the braze alloy. On the other hand, failure of the braze alloy can also result from cracks at the interface. In such a case, the fatigue resistance of the braze alloy plays an important role in determining the wheel's life. The wear resistance of the braze alloy can be improved by introducing suitable hard particles. It was found that a braze alloy of 77Cu-23Sn-12.5Ti-7.5Zr-10TiC-0.2C (by weight) exhibits excellent performance in a wear test (a ten fold improvement), which is further confirmed in the grinding test (a two fold increase in life). The fatigue resistance of the active braze alloy can be modified by either reducing the volume fraction of the brittle intermetallic phase in the braze and/or enhancing the ductility of the braze alloy matrix. A ductile active braze alloy can be achieved by combining the two-layer structure and two step brazing process. To aid dissolution and diffusion of the Cu atoms into the Cu/Sn/Ti braze alloy, a lower volume fraction of the intermetallic phase and higher ductile matrix of the braze can be achieved. Both have beneficial effects in modifying the ductility of the active braze alloy, and make removal of the braze alloy from the substrate by acid etching easier.
by Ren-Kae Shiue.
Ph. D.
4
Fursdon, P. M. T. "The continuous dress creep feed form grinding of titanium alloys." Thesis, University of Bristol, 1989. http://hdl.handle.net/1983/5e6c03d3-5847-415b-9967-65eac98f156e.
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5
Dzebo, Sead. "Investigation of methods to improve process performance in centerless grinding of Inconel 718 and Ti-6Al-4V superalloys." Thesis, Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37113.
Full textAbstract:
Grinding is an abrasive machining process used for the final shaping of components that require very smooth surfaces and a high dimensional accuracy. In recent years, the costs of industrial grinding operations have increased with a greater demand for high-strength, low-weight superalloy components. Titanium and nickel-based alloys are desirable for their high creep-rupture strength and corrosion and oxidation resistance in high-temperature environments. However, they are very difficult to grinding due to a combination of poor thermal properties, rapid work-hardening, and a high level of chemical reactivity. In this thesis, two methods are investigated to improve process performance in plunge centerless grinding of Inconel 718 and Ti-6Al-4V superalloy fasteners: (i) economic optimization of grinding process parameters and (ii) reduced quantity lubrication using a graphite nanoplatelet-enhanced grinding fluid. In the first part, a systematic methodology is presented for finding the optimum parameters in two stages: (i) modeling of process and part quality constraints, and (ii) determination of optimum grinding conditions in the feasible operating region. In the second part, the performance of a graphite nanoplatelet-enhanced grinding fluid in reduced quantity lubrication centerless grinding is evaluated to assess its potential as a cost-effective alternative to the traditional flood cooling method. The results of the study indicate that an appreciable reduction in the cost of the superalloy grinding operation can be achieved by operating at the optimum parameters. In addition, it is shown that the application of a graphite-enhanced fluid at a reduced flow rate is more effective than high-volume flood cooling in reducing specific grinding energy levels and wheel wear rates, thus offering the potential to increase process productivity.
6
Bhaduri, Debajyoti. "Ultrasonic assisted creep feed grinding and dressing of advanced aerospace alloys." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5415/.
Full textAbstract:
The research involves the investigation of hybrid ultrasonic assisted creep feed grinding (UACFG) of advanced aeroengine alloys, in particular Inconel 718, CMSX-4 and gamma titanium aluminide (γ-TiAl). For tests with ultrasonic vibration, workpieces were actuated at a constant frequency (~20kHz) via a specially designed block sonotrode attached to a 1kW piezoelectric transducer-generator system. The trials on nickel based superalloys were carried out using open structured alumina wheels whereas γ-TiAl specimens were machined with conventional silicon carbide and single layer diamond superabrasive wheels. Statistically designed experiments involving variation in wheel speed, table speed, depth of cut, grinding condition and vibration amplitude were employed in mainstream testing. Reductions in grinding force components were typically observed albeit at the cost of higher wheel wear and surface roughness of the ground slots when ultrasonic assisted grinding of nickel alloys. Conversely, UACFG of γ-TiAl exhibited lower grinding wheel wear and workpiece surface roughness. Surfaces ground with the assistance of vibration generally revealed greater side flow/ploughing and overlapping grit marks in comparison to standard creep feed ground specimens. Three dimensional topographic measurement of grinding wheel surface replicas indicated that ultrasonic vibration led to an increase in the number of active cutting points on the wheel.
7
Rayner, Joshua Lee. "A finite element simulation of thermal profiles in grinding of titanium aluminide." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/18967.
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8
Wojtewicz, Michał. "Research on the influence of grinding wheel impregnation with anti-adhesive substances on the efficiency of nickel based alloys grinding process : PhD thesis summary." Rozprawa doktorska, [s.n.], 2017. http://dlibra.tu.koszalin.pl/Content/1049.
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9
Shajari, S., and R. Sarraf-Mamoory. "The Effect of Raw Materials Molar Ratio in Mechanochemical Synthesis of Amorphous Fe-B Alloy Nanoparticles." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34897.
Full textAbstract:
In this study, amorphous iron-boron alloy nanoparticles successfully synthesized by mechanochemical
method. The raw materials were ferrous sulfate heptahydrate (FeSO4.7H2O) as a source of iron and sodium
borohydride (NaBH4) as a reducing agent. Powders grinding was performed with different
NaBH4/FeSO4.7H2O molar ratio. The results revealed that high active and completely amorphous particles
could be synthesized with the molar ratio of 4:1 for NaBH4:FeSO4 in 10 minutes of grinding time. Various
characterizations, such as the chemical analysis, atomic absorption spectroscopy (AAS), fourier transform
infrared spectroscopy (FT-IR), x-ray diffraction (XRD) and field emission scanning electron microscopy
(FESEM) have been performed. The XRD results confirmed the formation of the amorphous phase. Other
results also indicate the formation of amorphous alloy nanoparticles with an average particle size below 50
nm and the composition was Fe-10 Wt
percent B.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34897
10
Zhao, Zhijun. "Role of surface active layers on localized breakdown of aluminum alloy 7075." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1160670830.
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11
Kassam, Tahsin Ali. "The effects of Alumina purity, TICUSIL® braze preform thickness and post-grinding heat treatment on the microstructure, mechanical and nanomechanical properties of Alumina-to-Alumina brazed joints." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/15311.
Full textAbstract:
Alumina-to-alumina brazed joints were formed using 96.0 and 99.7 wt.% Al2O3 ceramics in as-ground and in ground and heat treated conditions using TICUSIL® (68.8Ag-26.7Cu-4.7Ti wt.%) braze preforms of thicknesses ranging from 50 to 250 μm. Brazing was conducted in a vacuum of 1 x 10-5 mbar at 850 °C for 10 minutes. Joint strengths were evaluated using four-point bend testing and were compared to the flexural strengths of standard test bars according to ASTM C1161-13. Post-grinding heat treatment, performed at 1550 °C for 1 hour, did not affect the average surface roughness or grain size of either grade of alumina but affected their average flexural strengths, with a small increase for 96.0 wt.% Al2O3 and a small decrease for 99.7 wt.% Al2O3. Post-grinding heat treatment led to secondary phase migration, creating a fissured 96.0 wt.% Al2O3 surface. This affected the reliability of 96.0 wt.% Al2O3 brazed joints, in which braze infiltration was observed. As the TICUSIL® braze preform thickness was increased from 50 to 150 μm, the average strengths of both 96.0 and 99.7 wt.% Al2O3 brazed joints improved. This occurred due to a microstructural evolution, in both sets of joints, which was studied using SEM, TEM and nanoindentation techniques. An increase in the TICUSIL® braze preform thickness increased the amount of Ti which was available to diffuse to the joint interfaces. This led to increases in both, reaction layer and braze interlayer thicknesses. Excess Ti in joints that were made using TICUSIL® braze preforms thicker than 50 μm, led to relatively hard Cu-Ti phases in an Ag-Cu braze interlayer. Cu-Ti phase formation, which may have reinforced joint strength whilst also reducing CTE mismatch at the joint interface, also led to Ag-rich braze outflow at the joint edges. Brazed joints made using as-ground 96.0 wt.% Al2O3 consistently outperformed brazed joints made using as-ground 99.7 wt.% Al2O3, due to the formation of Ti5Si3 phases at locations where the Ti-rich reaction layer intersected with the triple pocket grain boundary regions of the as-ground 96.0 wt.% Al2O3 surface.
12
Abdellaoui, Mohieddine. "Transitions de phases sous chocs mécaniques : mécanosynthèse du système magnétque Fe-Si." Paris 6, 1994. http://www.theses.fr/1994PA066294.
Full textAbstract:
La mécanosynthèse, découverte dans les années 70, est un procédé prometteur dans le domaine d'élaboration des phases hors équilibre présentant des propriétés physiques intéressantes dans différents domaines d'applications manocomposites, nanocéramiques, superalliages, phases hautes températures, phases amorphes, solutions solides sursaturées etc. Cependant, il existe des lacunes considérables dans les connaissances de base relatives à ce procédé. Pour cela des modélisations numériques du processus de mécanosynthèse dans des broyeurs planétaires et horizontaux ont été effectuées. Par ailleurs, l'amorphisation du système Fe - Si (cote riche en Fe) et l'augmentation de la concentration Si dans le Fe ont fait l'objet de nombreuses études motivées par les bonnes caractéristiques magnétiques de ce matériau. Se fondant sur son apport considérable dans le domaine de formation de phases amorphes et de solutions solides sursaturées, nous avons utilisé la mécanosynthèse pour l'élaboration d'alliages Fe - Si. Différentes études de diffractions des rayons x, de microscopie électronique en transmission (MET) et à balayage (MEB), de calorimétrie différentielle à balayage (CDB) de spectroscopie Mossbauer et de caractérisation magnétique ont été effectuées. Le chapitre 1 est une étude bibliographique des différentes applications de la mécanosynthèse suivie d'une analyse des différentes approches de mécanisme de transformations de phase sous tel type de sollication. La seconde partie du chapitre 1 porte sur les intérêts des alliages Fe - Si (cote riche Fe) dans le domaine magnétique suivie d'une analyse des différents travaux portant sur les transitions de phases induites par mécanosynthèse dans ce système. Le chapitre 2 est consacré à l'étude des paramètres physiques pilotant les transformations de phases par mécanosynthèse. Le chapitre 3 traite les transformations de phases induites par mécanosynthèse dans les alliages Fe - Si (cote riche fer). Les résultats expérimentaux montrent l'obtention d'une phase amorphe et d'une solution solide sursaturée du Si dans le Fe jusqu'à 37. 5% At. Si. Pour les teneurs en Si inférieures à 15% At. Le désordre chimique dans la solution solide A2 se fait d'une façon aléatoire suivant une loi binomiale dans une structure de coordinence 8. Pour les concentrations supérieures, l'état désordonné se présente sous forme de combinaison de plusieurs états de coordinence allant de 8 à 14. Les poudres synthétisées sont magnétiquement dures (coercitivité de l'ordre de 17 K A/M)
13
Chaumat, Valérie. "Equilibres de phases et microstructures d'alliages Nb-Ti-Al élaborés par mécanosynthèse." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0073.
Full textAbstract:
L'amelioration des performances des moteurs aeronautiques et de certains dispositifs nucleaires necessite l'augmentation des temperatures de fonctionnement des pieces chaudes en contact avec des milieux dont la temperature peut varier de 900 a 1600c. C'est dans ce contexte que sont etudies les alliages a base de niobium du systeme nb-ti-al. Dans ce systeme, ce travail a cherche a approfondir la connaissance des equilibres de phases, dont dependent les proprietes, ainsi que l'interet technique de l'elaboration par broyage de poudres (mecanosynthese). Deux approches, l'une theorique par la methode variationnelle des amas, l'autre experimentale par diffraction de neutrons, ont permis de determiner les limites en temperature et en composition du domaine d'existence de la phase ordonnee de structure cubique centree b2 dans le systeme nb-ti-al. Il apparait ainsi que ce domaine est particulierement etendu vers les teneurs riches en niobium. Nous avons egalement constate que la temperature de transition ordre - desordre b2 a2 et le degre d'ordre sont tres sensibles aux variations de composition. Par ailleurs, nous avons montre la possibilite d'elaborer par mecanosynthese a partir des elements constitutifs nb, ti, al des alliages a base de niobium du type nb-ti-al repondant aux specifications de purete et d'homogeneite de composition. Une attention particuliere est portee a l'analyse des mecanismes de transformation de phases au cours du broyage et de la densification
14
Chang, Chang-Hung, and 張長宏. "The Effects of Cutting Fluid with Nano Particles on the Grinding Ti Alloys." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/40910068415141277568.
Full textAbstract:
碩士臺灣大學
機械工程學研究所
95
The contents of this article chiefly explain the effects on grinding Ti-6A1-4V when using nano-fluid and the general water-based fluid. Assisting this effect by using the production of MQL and the cutting fluid method to analyze and compare. The contents analyze and inspect the differences when using nano- fluid, water-based fluid and MQL through the usage of wheel leading and wear, grinding force, surface of workpiece and roughness, also to analyze the diversification. The conclusion of this experiment is that MQL is the most effective to reduce wheel leading, and is most prone to achieve better surface of workpiece and roughness than the general wet grinding. Different kinds of cutting fluid also use the method of MQL in order to most effectively reduce roughness. When using MQL, we acquire a flatter workpiece in order that we could economize the finished cost and to enhance efficiency.
15
Wong, Man-Fang, and 翁曼芳. "The Research of Hydriding Characteristics for Mg-Ti and Mg-Al Alloys by Reactive Mechanical Grinding." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/24583487495934971810.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
99
Mg-Xwt%M(X=0、10)(M=Ti、Al) Mg-based hydrogen storage alloys was prepared by reactive mechanical alloying. The synthesis was done at room temperature under 3atm of hydrogen using a planetary ball milling device for 6 hours. The morphological and microstructural characteristics by scanning electron microscopy (SEM), BET surface analysis. We determine phase structure and evolution by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal dehydriding properties by thermo gravimetry/differential thermal analyzer (TG/DTA). After the reactive mechanical alloy, the particle size of the power was reduced, as compared with those of the starting materials. The magnesium hydride (MgH2) was formed by the ball milling for 6 hours. The hydrogen storage properties were measured with at temperature of 325°C、350°C and 375°C. For the hydrogen storage characterization, the additions of titanium improved the hydrogen absorption capacity. When activation was completed after two hydriding – dehydriding cycles, the maximum hydrogen absorption content was 3.63wt% at 350°C. The XRD results showed that the addition of Ti and Al improved the resistance towards oxygen contamination.
16
LU, WEN-CHUN, and 陸文俊. "The Research of Hydriding Characteristics for Mg-xTi-2xFe Series Hydrogen Storage Alloys by Reactive Mechanical Grinding." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/gxkra2.
Full textAbstract:
博士國立高雄應用科技大學
機械工程系
105
Magnesium-based hydrogen storage alloys have excellent hydrogenation properties and high hydrogen storage characteristics. But the grinding of the surface on the magnesium and alloys easily form a dense oxide layer;It is necessary to undergo multiple activation for gaining higher efficiency of hydrogenation then release hydrogen at a higher temperature. The characteristics of the Ti-Fe system are the inexpensive materials and easily reversible hydrogenation under the room temperature and atmospheric pressure. However, it is sensitivity to oxidation and has poor resistance to the poisoning of impurity gas. In this study, Ti and Fe were added into the Mg powder with different proportions, Mg and Ti were added as the second and the third elements, the weight percentage was set to Mg-xTi-2xFe to investigate the crystal composition, structure, hydrogen absorption and desorption properties, in order to find the best hydrogen storage materials. From the table of PCT, We know that the sample with Mg-15% Ti-30% Fe is the most reasonable condition; the following advantages can be obtained: 1. Magnesium does not adhere to the mill wall during milling, which helps to achieve grinding of nano-amorphous hydrogen storage alloy powders. 2. Simply activated, the sample powder can be in the low-pressure state and 320 ℃ for hydrogen absorption and desorption. 3. Non-hydrogenated magnesium accounts for only about 24.9% of the total Mg, which is much better than 59.9% of the pure Mg. 4. Excessive Fe clusters on the surface of the substrate, which protects the A element from oxidation, and acts as a catalyst in the hydrogen absorption and desorption. 5. These elements and amorphous compounds have different thermal expansion coefficients, which leads to the expansion of the powder and the cracking of matrix in the heating. After heating, the A element and AB amorphous compounds increases the fresh surface, which is exposed to hydrogen atoms and undergo hydrogenation. The hydrogen molecules combine with the A element and the AB amorphous compound to form AH2 and HAB amorphous compounds.
17
LIN, TING-YI, and 林庭毅. "Analysis and optimization of machining parameters for the bolt of Inconel 718 nickel-based alloys in the finishing grinding process." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/n8bb27.
Full textAbstract:
碩士修平科技大學
精密機械與製造科技碩士班
106
This research presents the finishing grinding process for the surface processing of Bolt of Inconel 718 Nickel base alloy. Feed rate and grinding depth, types of grinding wheels, grinding fluid used as the processing parameters to observe the processing characteristics, such as machined surface and surface texture, chip. Using the response surface method (RSM) to generate second order mathematical module explained the relationship between the processing parameters and quality characteristics. The results show the higher feed rate, lower grinding depth and using grinding fluid to reduce the surface roughness values and to obtain better surface quality. The lower toughness and higher the hardness and grin size of wheel is more suitable for milling Inconel 718 nickel-based alloys, and using the grinding fluid minimizes the surface roughness value. Optimum processing parameters obtain its optimal surface roughness values compared with the initial surface roughness values reduced 62.2%.
18
Lin, Sing-Min, and 林賜民. "Studies on Precision Grinding Characteristics of Chromium - Molybdenum Alloy Steel." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/29588365628656821941.
Full textAbstract:
碩士國立成功大學
機械工程研究所
82
This thesis investigates the grinding characteristics of chromium-molybdenum alloy steel with the vitrified bonded CBN (cubic boron nitride) and Al2O3 wheel. The grinding forces, surface roughness and wheel wear were measured under various grinding conditions, and an optimum grinding condition was obtained. Using the 3-axis machining center, dynamometer and surface roughness testing machine, the grinding force and the surface roughness of the specimem under various grinding conditions for both alumina oxide and cubic boron nitride wheel. The experimental results showed that te grinding performance with cubic boron nitride is superior to that with alumina oxide. Based on the experimental results of this study, an optimum grinding condition was applied to the grinding of variable pitch lead screw with conical meshing elements. Then, the surface quality of the screw was measured.
19
Hsu, Yi-Chia, and 徐繹佳. "Coated abrasive disc grinding of titanium alloy with minimum quantity lubrication." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/07343385937129597827.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
105
This paper presents the mechanics of grinding titanium alloys (Ti-6Al-4V) in minimum quantity lubrication to the aspects of material removal, surface integrity, temperature and wear of coated abrasives following with confirmation in experimental works. In slumping of soda-lime glass with titanium mould, surface quality and integrity were greatly improved however surface finish on the titanium mould was still problematic due to its inherence low thermal conductivity. In this work, the developed analytical model suggested the influences of grit number, grinding speed, normal load pressure and MQL on the material removal rate and surface quality. When the developed model was calibrated with experimental results, the appreciable precision level of 83.98% was resulted. The maximum material removal (89 mg/min) was produced when 150 mesh grits, (0.7 bar) normal pressure, (5 bar) blasting pressure of MQL and grinding speed of (3200 m/min) were employed. The produced fine surface (~Ra 0.1 μm) demonstrates the evolution of the adhesion, plastic deformation following the fretting and sealing actions on the workpiece surface. Whilst MQL provided instant effects to the work’s hardening and thermal softening in grinding, the improvement of microhardness (~395HV0.025) prolonged the tool life and benefited the productivity.
20
Yu, Yi-Hsun, and 余奕勳. "Study on Abrasive Electrical Discharge Grinding for Nickel-based Alloy Inconel 718." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/04742199226887494336.
Full textAbstract:
碩士雲林科技大學
機械工程系碩士班
96
In this study, the grinding process has been investigated in the machining of nickel-based alloy Inconel 718 with traditional grinding and abrasive electrical discharge grinding (AEDG) technology. Moreover, grinding force, surface roughness and grinding wear will be discussed in this study. Three parts are discussed in this study: (a) using a dynamometer to measure the tangential grinding forces of grinding wheel and to analyze the data with PC, understanding the effects and improvements by introducing AEDG technology; (b) analyzing the surface roughness and grinding wear after abrasive electrical discharge grinding; and(c) discussing the feasibility of regression analysis on the AEDG. In the results of the AEDG experiment, grinding with electrical energy can effectively reduce the grinding force about 34%. The surface roughness is improved about 9%, but grinding wear is increased. We found that the maximum error of regression analysis prediction can be controlled within 25%
21
Ｗeng, Yu-Liang, and 翁煜喨. "Study on the ultrasonic assisted grinding of the super-alloy with various frequencies." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7w35ct.
Full textAbstract:
碩士國立清華大學
動力機械工程學系
106
Cemented Carbide is a hard material with great strength, hardness and wear resistance as a cutting tool and mold. However, the process of manufacturing has become quite difficult because of its characteristics. Therefore, grinding tungsten carbide which is one of the Cemented Carbide were studied in this thesis. Ultrasonic Assisted Grinding(UAG) has been verified that it can be used to grind hard materials such as Cemented Carbide efficiently. In this thesis, the frequencies of the ultrasonic assisted grinding were further tested by using the Tungsten Carbide as the experimental object. The experiment was based on material removal rate, surface roughness, grinding force, specific grinding energy and surface condition of the workpiece. Finally, the influence of frequencies on ultrasonic assisted grinding is understood according to the relationship between the result of grinding experiments and the parameters of the experiments so that the appropriate frequency dealing with Cemented Carbide such as tungsten carbide will be selected in the future.
22
Hsu, Ming-Hsien, and 徐明賢. "A Study on Grinding Performance with Cryogenic Cooling and Minimum Quantity Lubrication for Titanium Alloy." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/wpfxrf.
Full textAbstract:
碩士國立虎尾科技大學
創意工程與精密科技研究所
99
Along with widening applications of titanium alloy, the requirement to the machining quality of related parts has been heightened, and their functions could be fulfilled only through grinding process. Due to the low thermal conductivity and high chemical activity of titanium alloy, the high temperature of grinding would be concentrated on the surface layer, which would cause the grinding wheel adhesion and loading, as well as heat damage on the ground surface. Numerous difficulties have become the major factors resulting in its failure of extensive application. For this reason, this study investigated the grinding performance and grinding quality in combination of the green manufacturing technology under hot research both at home and abroad. This study conducted the grinding experiment on titanium alloy by two kinds of green manufacturing technologies (minimum quantity lubrication and liquid nitrogen cooling), and the conventional coolant by CBN grinding wheel. Dynamometer and spectrum analyzer were used in the grinding experiment to monitor the grinding force and vibration, respectively. The chips under different process parameters, surface morphology and surface roughness were observed to conduct analysis and discussion of the experimental data. The result showed that compared with the conventional coolant grinding, the minimum quantity oil mist provided lubrication for the grinding zone, as well as cooling effect of compressed air to reduce grinding wheel adhesion so as to reduce the grinding force. Observation on the flowing-type chip found that the minimum quantity oil mist improved the grinding conditions, and achieved a better ground surface quality than that of the conventional coolant grinding. Processing by cryogenic cooling has exhibited the cooling advantages and characteristics to maintain the grinding area at a low-temperature state, which could help to reduce material toughness of the workpiece and the grinding wheel adhesion resulted by chemical activity. Moreover, it could also maintain the abrasive grit under a sharp status to improve the grinding performance, and keep the grinding force, vibration magnitude and surface quality controlled under a lower and stable level. From the synthesis results and investigations, it shows that when increasing wheel speed and decreasing depth of cut that will be reduced the grinding force and grinding wheel adhesion, and the quality of ground surface will thus be improved.
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Zeng, Yi Zhong, and 曾一中. "Study on Rotary Ultrasonic Spindle Combined with Flexible Tool Holder for Surface Grinding of Hard Alloy Material." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/89269957699387673833.
Full textAbstract:
碩士國立高雄應用科技大學
模具工程系
105
Tungsten carbide is usually difficult to cut by traditional machining methods. Generally, the machined surface roughness by CNC machine tools cannot reach mirror quality, they must rely on manual polishing for a very long time in the past. In this study, a novel design of flexible tool with a fixed diamond abrasives combined with rotary ultrasonic machining (RUM) spindle is conducted to reduce the labor force significantly. The newly designed flexibility of tool-tip is to prevent overcutting from the CNC grinding. The grinding conditions with resulted surface morphology of the tungsten steel were investigated and analyzed. The optimized operating conditions are obtained through Taguchi design of experiment and ANOVA variance analysis. L16 Taguchi Method are conducted first by using the tool with rough abrasives of # 400 mesh (38μm grain). The major contribution factors for enhancing material removal rate (MRR) are grinding depth> spindle speed> feed rate. The optimized combination by ANOVA is the set of spindle speed 5000 rpm, feed rate 5mm/min, grinding depth of 12μm, with flexible tool holder, and with ultrasonic assistance. Its highest MRR can reach up to 0.72mm3/min. For the quality of surface roughness (SR), the main contribution factors are kinds of tool holder> grinding depth> spindle speed. The optimized parameters are under spindle speed 5k rpm, 5 mm/min, depth 3μm, with a flexible holder, and without ultrasonic power. Its minimum three-dimensional SR can reach up to Sa 0.44μm. Secondary, for the fundamental polishing survey by using #1000 abrasives (13μm grain) and 3μm of depth with 7k rpm speed combined with the RUM, roughness reaches about Sa 0.25μm, which is 24% better than no-RUM polishing. If it is done at 10 mm/min feed rate combined with RUM, its roughness reaches Sa 0.33μm, which is also 21% better than the conventional no-RUM processing. Their Z-axis polishing force increases with the increase of the feed rate, and decreases with the spindle speed. Generally, the polish force by using RUM is smaller than that by no-RUM, and the difference gets larger as the polish depth gets deeper. The three-dimensional SR also decreases with the increase of the spindle speed and the deceleration of the feed rate. Furthermore, L9 Taguchi Method and ANOVA optimization analysis reveal: for straight linear path, it is suggested that with the 100% ultrasonic power, combined with 5k rpm, and 9mm/min feed rate, the best surface roughness reaches Sa 0.418μm. It is also suggested for cycloid path that feed rate of 9 mm/min, 6000 rpm and without RUM can reaches best flatness of 0.29μm, and the lowest surface roughness Sa 0.185μm. Based upon the above results, this study confirms the feasibility of the newly designed flexible tool, and that contribute to the CNC ultrasonic machine tool as a novel polishing strategy for tungsten steel molds.
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Kao, Jin-yao, and 高靖堯. "Study of hydrogenation property of Mg-Ni-Fe series hydrogen storage alloy prepared by mechanical ball-grinding." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/19371133428399754566.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
98
Abstract In this study , preparing hydrogen storage alloy powder by high energy mechanical ball grinding, and the method can be reached the two purpose of alloying and surface modification, then add the different element as a catalyst to explore through a variety of magnesium hydriding kinetic properties, crystalline structure, surface topography. Magnesium-based hydrogen storage alloy are very promising materials for hydrogen storage due to their high hydrogen capacity and low-cost, but MgH2 desorbs hydrogen very slowly. In the experiment , magnesium-rich Mg–Ni–Fe compounds have been prepared by high energy mechanical ball grinding , and trying to improve the hydrogen absorption and desorption kinetics . According the experiment results , the Mg-Ni sample should be have the higher hydrogenate rate, but the composited appear two plateau the lower and wider corresponding to the MgH2 phase and the upper and shorter corresponding to the Mg2NiH4 phase. Between the two plateau , MgH2 absorption and Mg2NiH4 desorption , this phenomenon led to the error value record. Mg-Ni composited has max hydrogen absorption capacity of 4.37wt.% at 573K, hydrogen absorption rate 0.075wt.%/min; Mg-Fe composited got the max hydrogen absorption capacity of 4.45wt.% , hydrogen absorption rate 0.092wt.%/min; Mg-Ni-Fe composited got max hydrogen absorption capacity of 4.21wt.%, hydrogen absorption rate 0.08wt. %/min.
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Chang, Yu-Fu, and 張祐福. "Fabrication of Ni – Co Alloy Co-deposition of Micro Diamond Tool and Its Applications to Synchronous Electrical Discharge Grinding." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/qsy5rt.
Full textAbstract:
碩士國立高雄應用科技大學
模具工程系碩士班
102
This research attempts to achieve a synchronized hybrid process of micro-EDM grinding (micro-EDMG, or μEDMG) on a single machine, it is aimed at saving the secondary precision grinding process after general micro-EDM process in micro-machining fields. First, the micro-tool of tungsten carbide was dressed to 0.3 mm diameter by a WEDG (wire electrical discharge grinding) system, and co-deposited in the nickel electro-plating bath with 6~12 μm of diamond abrasives. A low speed spindle is used for electro-plating, and then, another high speed spindle up to 20 KRPM is adopted to perform synchronous process of micro-EDM grinding. In our previous studies, it had been confirmed the feasibility of the synchronized micro-EDM and micro grinding process with 10 μm of lateral depth into work piece by precision positioning. However, there were severe problems of residual craters and debris accumulation, causing by the secondary discharge between both electrodes. This study proposes two methods to overcome the defects and increase machining quality compared to the previous researches. One of them is to dress standard cylindrical micro-tool into the helical groove with a short taper, making the spiral grooves serve as the chips pocket to increase debris expelling efficiency. By appending cobalt ion into the plating bath to achieve Ni-Co alloy co-deposition, it is found that both more uniform dispersion of abrasives on the tool’s surface and richer diamond grains and stronger mechanical property in wearing resistance are achieved. By doing so, significant improvement of the precision quality and machining efficiency for such a hybrid process, and the anti-worn out capability of the micro-tool are verified through the conducted surface of micro-holes. Moreover, only one step of processing is required on the same machine and both higher efficiency and better quality by applying micro diamond tools to fabrication of under 0.33 mm micro-holes co-axially and precision circle with 0.3 mm thick of SUS-304 is achieved. Fabrication conditions of micro diamond tools by Ni-Co co-deposition is conducted under Ni-Co/Diamond bath with 5 g/l of abrasives concentration, 2 RPM of rotation, 7 ASD of current density, and electro-plating interval of 5 min. It was verified from EDS analysis that the diamond amount occupied 31.77 wt(%) and cobalt element occupied 11.31 wt(%). Such a micro-tool with processes parameters of 20 KRPM, 30 μm/min and feeding depth of 2 mm depth achieved the best surface roughness of Ra 0.107 μm. Its diameter difference between entrance and exit also appeared to be the value of 9 μm. From oscilloscope observed EDM waveform and the 10 μm scaled SEM picture of tool’s profile, it is confirmed that synchronous micro-EDMG occurred during the operation processes. Furthermore, it is found from the machined surface that there are three phases of EDMG processes contributed to this novel strategy. Namely, the first phase during machining depth of 0~1.0 mm along z-direction, it is dominated by micro-EDM drilling with roughing current of 0.5A. There is almost no grinding, or the grinding chips are totally re-discharged again by the second discharge process. The second phase during 1.0~1.5 mm is contributed to rough EDM grinding of the micro holes, some recast layers are pulling-pushed or scratched, and some craters are refilled to some sort of level. There seems some kind of hybrid machining effects around EDM spark’s spot. Finally, the third phase during 1.5~2.0 mm, there are some sort of complete grinding to remove the recast layers and craters to a fine surface in this finishing stage. Besides, from SEM photo of 1 μm scale, it is found that not only simply EDM or simply mechanical grinding, but also plastic machining regions observed. They are contributed from micro-scale removing mechanism during micro-EDMG processes, in which recast layers are pulling-pushed and scratched to longer chips, and some craters are refilled again. On the other way, due to such a short period of EDM pulse on-time, the shoveled chip by grinding abrasive is the most possible position to be re-discharged again to shape a non-typical EDM crater. Keywords: micro-EDM (electrical discharge machining), micro-EDMG (micro-EDM grinding), synchronous processes, hybrid Ni-Co co-deposition, Diamond Tool
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Chinomona, Benvolence, and 齊班諾. "Modelling of Working Temperature in Dry and Minimum Quantity Lubrication Grinding of Aluminum Alloy (6061-T6) Using Coated Abrasive Disc." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/7x5a59.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
105
Grinding process results in high heat generation at the workpiece-grain interface and most of the heat goes into the workpiece, another fraction is absorbed by the grain and removed by MQL. These high temperatures to the workpiece causes rapid wear of the abrasive grains, surface and sub-surface alteration of the workpiece. A model of the working temperature in both dry and minimum quantity lubrication was developed. In this study, NaHCO_3 particles were spread out with high-pressure air when the threshold of 40°C was exceeded. The results show that the utilization of the surfactant can reduce the working temperature and heat-affected zone efficiently. The hardness of the workpiece is high when the surfactant is applied due to the reduction of the rubbing behavior or efficient dispassion of heat. The simulated results indicate that during dry grinding the temperature rise is rapid as compared to the MQL grinding. The high temperature in dry grinding might be because of immediate wear of the coated abrasive grain, which results in an increase of frictional heat due to large contact area between the abrasive grain and workpiece. The effects of grinding parameters such as mesh size are also analyzed in this study. It is observed that using an abrasive disc of 150 mesh size high temperatures were recorded as compared to 600. The simulation results were verified by the experiments.
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Hsu, Chuan-Fu, and 徐銓甫. "Taguchi-Fuzzy-Based Multi-Objective Optimization Study on Grinding Nickel-based Alloy Inconel-718 with Nanofluid-Mixed /Ultrasonic Atomization MQL System." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/sfrkb2.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
105
This thesis is focused on the combined application of Taguchi-Fuzzy method Nanofluid/Ultrasonic Atomization MQL in the grinding process of Inconel-718 Nickel-based Alloy through ultrasonic shock dispersion and atomization characteristics to overcome the concentration problem of nano-particles in the fluid, exploring the effectiveness of the lubrication system for Inconel-718 materials in the grinding process and establishing a set of multiple quality characteristics optimization of grinding process parameters. In this study, the Taguchi method was adopted along with the L18(21×37 ) orthogonal table to devise the combinations of the grinding parameters, the control parameters such as the nozzle distance, types of mixed nanoparticles , weight fractions of nanofluid, mixing ratios atomization quantity, air pressure, table speed , and tangential velocity. Also, the parameters obtained from the experiments such as grinding temperature, grinding force, and surface roughness are used as the indicators of the quality characteristics. The appearance of the processed surface is also observed. After integration the experimental data and retrieve the signal-to-noise ratio (S/N ratio) of each quality characteristic index, the S/N ratio is converted into gray correlation coefficient by gray correlation analysis, and substituted into the fuzzy inference system to derive Multiple Performance Characteristic Index(MPCI) of multiple quality characteristics.The maximum value of the measure is the optimal combination of multi-quality characteristic parameters. The results demonstrated that the optimal parameter of the multi-quality characteristic is A1 ( nozzle distance 60 mm)、B1( Mixed Nanoparticle type MoS2/Al2O3)、C3( mass fraction of nanofluid 1 wt%)、D3( mixing ratio 2:1),E2( atomization quantity 25 ml/h)、F3( air pressure 3 bar)、G1(feed rate for rotary table 3 m/min),H2( tangential velocity 24 m/s) , a grinding temperature of 166.4°C, a surface roughness of 0.273 μm and a grinding force ratio of 0.075. This combination of multi-quality characteristic optimization parameter was applied to compare with different sliding methods including base fluid/MQL, base fluid/ultrasonic atomization MQL, nanofluid/MQL , nanofluid/ultrasonic atomization MQL to look into the differences between various lubrication methods. From the comparison results, it is found that the best lubrication method is the optimized grinding temperature, grinding force, surface roughness and workpiece surface condition for nanofluid/ultrasonic atomization MQL.
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Chang, Hsiao-Cheng, and 張孝崢. "Optimization and analysis the surface roughness of Ti-6Al-4V titanium alloy in finishing grinding process with cold air gun coolant system." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/61316330984336197399.
Full textAbstract:
碩士修平科技大學
精密機械與製造科技碩士班
104
The machinability evaluation of cold air gun coolant system in the fine grinding process of Ti-6Al-4V titanium alloy was investigated by modeling and optimization. A high-quality cooling and lubrication system can effectively improve the quality of surface finish. Under normal circumstances, cutting fluids are customarily used to control the cutting temperature in the cutting zone. A cold air gun coolant system was used in the experiments and produced a jet of compressed cold air in the air-cooling process during the metal grinding cutting process. In this paper, the mathematical model was presented to model the machinability evaluation through the response surface methodology (RSM). The quadratic model of response surface methodology associated with the sequential approximation optimization (SAO) method would be used to explain the relation of the finishing grinding process parameters and machining characteristic, and to find optimum values of machining parameters for the face cutting process of Titanium alloys. Observed in experiments, the cold air flow increases and reduce the cold air temperature will get better cooling and lubrication between the grinding wheel and the workpiece. Also reduce the friction and adhesion of materials, thus obtaining better quality of surface finish. The results of the experiment was confirmed by analysis of variance (ANOVA). All the experiment values are found in 95% prediction interval, and it’s enough to confirm the accuracy of the quadratic model. Using the optimum values of machining parameters for the finishing grinding process, compared with the best surface roughness Ra value and the initial value of the surface roughness was reduced 22.5%.