Dissertations / Theses on the topic 'Hard machining'
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1
Churi, Nikhil. "Rotary ultrasonic machining of hard-to-machine materials." Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/2509.
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Knuefermann, Markus M. W. "Machining surfaces of optical quality by hard turning." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/131.
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The main aim of this work was the machining by hard turning of surfaces with optical surface quality. A numerical target had been set as a surface roughness Ra = 10nm. It has been shown that achieving roughness of that magnitude by hard turning is possible. Individual work pieces exhibited the desired surface properties for short lengths at a time, but it proved to be very difficult to achieve these surfaces consistently and over longer cuts. The factors influencing the surface roughness were identified as tool defects and machine vibration in addition to the standard cutting parameters and choice of cutting tool. A model of surface generation in hard turning has been developed and good correlation between simulated and experimentally determined surface roughnesses was achieved. By introducing a material partition equation which determines the proportional contribution of material removal mechanisms in the undeformed chip a comprehensive method for assessing the contributing factors in material removal was developed. While it has been shown that surfaces in hard turning are almost exclusively generated by chip removal and plastic deformation the developed model is versatile enough to include elastic deformation of the work piece. With the help of the model of surface generation in hard turning it has been possible to attribute magnitudes of the influencing factors with respect to the cutting parameters such as feed rate and tool corner radius, and the main disturbances - tool defects and machine vibration. From this conclusions were drawn on the requirements for machine tools and cutting tools, which will need to be realised to make ultra-precision hard turning of surfaces of optical quality a feasible manufacturing process.
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Rashid, Waleed Bin. "Surface defect machining : a new approach for hard turning." Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2840.
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Hard turning is emerging as a key technology to substitute conventional grinding processes, mainly on account of lower equipment cost, short setup time, and a reduced number of process steps. This is, however, being impeded by a number of challenges required to be resolved, including attainable surface roughness, surface deteriorations, surface residual stresses and metallurgical transformations on the machined steel surface (white layer). In this thesis, a novel approach named Surface Defect Machining (SDM) is proposed as a viable solution to resolve a large number of these issues and to improve surface finish and surface integrity. SDM is defined as a process of machining, where a workpiece is first subjected to surface defects creation at a depth less than the uncut chip thickness; either through mechanical and/or thermal means; then followed by a normal machining operation so as to reduce the cutting resistance. A comprehensive understanding of SDM is established theoretically using finite element method (FEM). Also, an experimental study has been carried out for extensive understanding of the new technique. A good agreement between theoretical and experimental investigations has been achieved. The results show very interesting salient features of SDM, providing favourable machining outcomes. These include: reduced shear plane angle, reduced machining forces, lower residual stresses on the machined surface, reduced tool-chip interface contact length and increased chip flow velocity, as well as reductions in overall temperature in the cutting zone and changing the mechanism of chip morphology from jagged to discontinuous. However, the most prominent outcome is the improved attainable surface roughness. Furthermore, SDM shows the ability to exceed the critical feed rate and achieve an optical surface finish upto 30 nm. A scientific explanation of the improved surface roughness suggests that during SDM, a combination of both the cutting action and the rough polishing action help to improve the machined surface. Based on these findings, it is anticipated that a component machined using the SDM method should exhibit improved quality of the machined surface, which is expected to provide tremendous commercial advantages in the time to come.
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Zhang, JingYing. "Process Optimization for Machining of Hardened Steels." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7248.
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Finish machining of hardened steel is receiving increasing attention as an alternative to the grinding process, because it offers comparable part finish, lower production cost, shorter cycle time, fewer process steps, higher flexibility and the elimination of environmentally hazardous cutting fluids. In order to demonstrate its economic viability, it is of particular importance to enable critical hard turning processes to run in optimal conditions based on specified objectives and practical constraints.
In this dissertation, a scientific and systematic methodology to design the optimal tool geometry and cutting conditions is developed. First, a systematic evolutionary algorithm is elaborated as its optimization block in the areas of: problem representation; selection scheme; genetic operators for integer, discrete and continuous design variables; constraint handling and population initialization. Secondly, models to predict process thermal, forces/stresses, tool wear and surface integrity are addressed. And then hard turning process planning and optimization are implemented and experimentally validated. Finally, an intelligent advisory system for hard turning technology by integrating experimental, numerical and analytical knowledge into one system with user friendly interface is presented.
The work of this dissertation improves the state of the art in making tooling solution and process planning decisions for hard turning processes.
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Pretorius, Cornelius. "Machining of titanium alloys with ultra-hard cutting tool materials." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4385/.
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This research explores the relative merits of existing and novel ultra-hard tool materials for finish turning titanium alloys. Phase 1 of the experimental work comprised evaluating the machinability of Ti-6Al-2Sn-4Zr-6Mo when employing carbide tooling with respect to tool life, wear behaviour, workpiece surface integrity and cutting forces. The machinability of Ti-6Al-2Sn-4Zr-6Mo using PCBN tooling was evaluated in Phase 2 experiments. It was shown that even with the use of high pressure jet cooling, carbide and low content PCBN grade inserts were unsuitable for high-speed (~200 m/min) finish turning of titanium alloys. Phase 3 research evaluated the machinability of Ti-6Al-2Sn-4Zr-6Mo and Ti-6Al-4V when employing PCD tooling with respect to tool life, wear behaviour, workpiece surface integrity and cutting forces. Benchmark tests producing response surface models were developed using conventional low pressure fluid supply and were found to be suitable for the prediction of tool life, surface roughness and cutting force within the range of parameters studied. The PCD inserts significantly outperformed both carbide (by a factor > 24) and PCBN (by a factor > 12) tools in high-speed finish turning, although the performance varied depending on the PCD structure, edge geometry, period of engagement, undeformed chip thickness and jet fluid parameters.
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Evans, R. "Focused ion beam machining of hard materials for micro engineering applications." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/4417.
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The Focused Ion Beam (FIB) milling of single crystal diamond was investigated and the beam drift and mill yield were quantified. The effect of water assistance on the milling of diamond was found to double the yield. The surface morphology that spontaneously forms during milling was measured and the mechanisms behind its formation investigated. The effect of gallium implantation on the diamond crystal structure was measured by x-ray diffraction. Chemical vapour deposited polycrystalline diamond (PCD) has been machined into micro scale turning tools using a combination of laser processing and FIB machining. Laser processing was used to machine PCD into rounded tool blanks and then the FIB was used to produce sharp cutting edges. This combines the volume removal ability of the laser with the small volume but high precision ability of the FIB. Turning tools with cutting edges of 39µm and 13µm were produced and tested by machining micro channels into oxygen free high conductivity copper (OFHCC). The best surface quality achieved was 28nm Sq. This is compared to a Sq of 69nm for a commercial PCD tool tested under the same circumstances. The 28nm roughness compares well to other published work that has reported a Ra of 20nm when machining OFHCC with single crystal diamond tools produced by FIB machining. The time taken to FIB machine a turning tool from a lasered blank was approximately 6.5 hours. Improvements to the machining process and set up have been suggested that should reduce this to ~1 hour, making this a more cost effective process. PCD tools with sinusoidal cutting prongs were produced using FIB. The dimensions of the prongs were less than 10µm. The tools were tested in OFHCC and the prongs survived intact. Changes to the machining conditions are suggested for improved replication of the prongs into metal. Sapphire was FIB machined to produce nano and micro patterns on a curved surface. The sapphire is part of a micro injection mould for replication of polymer parts. The comparative economics of hot embossing and injection moulding have been studied. Injection moulding was found to be the more cost effective process for making polymer parts at commercial production levels.
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Aussaguel, Pierre. "A simplified finite element simulation for hard turning 52100 steel." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19609.
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Ramesh, Anand. "Prediction of process-induced microstructural changes and residual stresses in orthogonal hard machining." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/18842.
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Kishawy, Hossam Eldeen A. "Chip formation and surface integrity in high speed machining of hardened steel /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ42858.pdf.
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Smith, Stephen R. "An investigation into the effects of hard turning surface integrity on component service life." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17526.
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Al-Zkeri, Ibrahim Abdullah. "Finite element modeling of hard turning." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1181928433.
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Armitage, Kelly, and n/a. "Laser assisted machining of high chromium white cast-iron." Swinburne University of Technology, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20070214.155302.
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Laser-assisted machining has been considered as an alternative for difficult-to-machine
materials such as metallic alloys and ceramics. Machining of some materials such as
high chromium alloys and high strength steels is still a delicate and challenging task.
Conventional machines or computer numerical control (CNC) machines and cutting
tools cannot adapt easily to such materials and induce very high costs for operations of
rough machining or finishing. If laser-assisted machining can be implemented
successfully for such materials, it will offer several advantages over the traditional
methods including longer tool life, shorter machining time and reduced overall costs.
This thesis presents the results of the research conducted on laser assisted machining of
hard to wear materials used in making heavy duty mineral processing equipment for the
mining industry. Experimental set up using a high power Nd:YAG laser beam attached
to a lathe has been developed to machine these materials using cubic boron nitride
(CBN) based cutting tools. The laser beam was positioned so that it was heating a point
on the surface of the workpiece directly before it passed under the cutting tool. Cutting
forces were measured during laser assisted machining and were compared to those
measured during conventional machining.
Results from the experiments show that with the right cutting parameters and laser beam
position, laser assisted machining results in a reduction in cutting forces compared to
conventional machining.
A mathematical thermal model was used to predict temperatures within the workpiece at
depths under the laser beam spot. The model was used to determine the effect of
various cutting and laser parameters on the temperature profile within the workpiece.
This study shows that laser assisted machining of hard to wear materials such as high
chromium white cast iron shows potential as a possible economical alternative to
conventional machining methods. Further research is needed before it can be
introduced in industry as an alternative to conventional machining.
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Kumar, Mukund. "Laser assisted micro milling of hard materials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41213.
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This thesis presents an investigation of novel laser assisted micromachining processes that addresses the limitations of micromachining of hard-to-machine materials. Two different laser assisted approaches are used to machine hard metals and high strength ceramics. For hard metals, the basic approach involves localized thermal softening of the workpiece material by focusing a solid-state continuous wave near infra-red laser beam in front of the micro milling tool (end mills of 0.1 to 0.5 mm diameter). By suitably controlling the laser power, spot size and scan speed, it is possible to produce a sufficiently large reduction in the flow strength of the work material and consequently the cutting forces and tool deflections. A force model is developed to predict the cutting forces in Laser Assisted Micro Milling (LAMM) of hard metals. For high strength ceramics, the approach involves use of a two step process. In the first step, thermal cracks are generated in a confined volume by the steep thermal gradients generated by laser irradiation of the workpiece. In the second step, the weakened region is removed by a micro grinding tool. The characterization and modeling of the process serve as bases for users of the two approaches to select optimal process parameters.
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Singh, Ramesh K. "Laser Assisted Mechanical Micromachining of Hard-to-Machine Materials." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19803.
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There is growing demand for micro and meso scale devices with applications in the field of optics, semiconductor and bio-medical fields. In response to this demand, mechanical micro-cutting (e.g. micro-milling) is emerging as a viable alternative to lithography based micromachining techniques. Mechanical micromachining methods are capable of generating three-dimensional free-form surfaces to sub-micron level precision and micron level accuracies in a wide range of materials including common engineering alloys. However, certain factors limit the types of workpiece materials that can be processed using mechanical micromachining methods. For difficult-to-machine materials such as tool and die steels, limited machine-tool system stiffness and low tool flexural strength are major impediments to the use of mechanical micromachining methods.
This thesis presents the design, fabrication and analysis of a novel Laser-assisted Mechanical Micromachining (LAMM) process that has the potential to overcome these limitations. The basic concept involves creating localized thermal softening of the hard material by focusing a solid-state continuous wave laser beam of diameter ranging from 70-120 microns directly in front of a miniature (300 microns-1 mm wide) cutting tool. By suitably controlling the laser power, spot size and speed, it is possible to produce a sufficiently large decrease in flow stress of the work material and, consequently, the cutting forces. This in turn will reduce machine/tool deflection and chances of catastrophic tool failure. The reduced machine/tool deflection yields improved accuracy in the machined feature. In order to use this process effectively, adequate thermal softening needs to be produced while keeping the heat affected zone in the machined surface to a minimum. This has been accomplished in the thesis via a detailed process characterization, modeling of process mechanics and optimization of process variables.
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Kalyanasundaram, Dinesh. "Mechanics guided design of hybrid laser/waterjet system for machining hard and brittle materials." [Ames, Iowa : Iowa State University], 2009.
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Hsiao, Ya-Tsun. "In-process evaluation of tool wear effects on surface roughness variation in hard turning /." free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9904848.
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Hjertstedt, Johan. "Ytstrukturer och processer för hårdbearbetning av kugghjul och axlar." Thesis, Linköping University, Department of Management and Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11262.
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Detta examensarbete har utförts vid Linköpings universitet i samarbete med Scania Transmission i Södertälje och behandlar kravsättning av ytstrukturer samt processer för hårdbearbetning av kugghjul och axlar. Aktuella artikelritningar innefattar endast krav för Ra-värde, den aritmetiska medelavvikelsen för ytjämnhetsprofilen (R-profilen). Förslag på nya parametrar enligt av Scania tillämpade SS-EN ISO standards har tagits fram, detta för att ge en noggrannare beskrivning av vilken ytstruktur som skall uppnås. Resultatet är generellt tillämpningsbart men fokuseras mot kugghjulens hål, plan och diametrar. Vidare presenteras en jämförelse mellan metoder så att transmissionsverkstäderna kan tillverka kugghjul/axlar på ett kostnadseffektivare sätt. Arbetet grundas på en litteraturstudie av handböcker och standards kompletterat med kartläggning av nuläget genom insamling av mätdata. En omvärldsanalys och några bearbetningsprover med hårdsvarvning har också utförts. Till skillnad från nuläget föreslås en övergång från att ange Ra-värde på ritningarna till att ange en övre gräns för Rz-värde som en begränsning av amplituden. Ytor i relativ rörelse och ytor som ingår i pressförband föreslås kompletteras med en undre gräns för Rz-värde samt en undre gräns för relativ bärighet. Med införandet av ett bärighetskrav ges även en specifikation för profilens fördelning. Angivelse av bearbetningsmetod och eventuellt bearbetningsmönster föreslås att anges i klartext på ritningen då parametrar som beskriver karakteristiska drag för olika bearbetningsmetoder visat sig väldigt variationsbenägna i nulägesanalysen. Jämförelse av hårdbearbetningsmetoder har visat att det i kombinationsmaskiner, hårdsvarvning och slipning, vore intressant att enbart hårdsvarva kugghjulens glidlagerytor, något som enligt bearbetningsprover och omvärldsanalys verkar rimligt. Detta bör efter godkännda riggprover anammas som ett första optimeringssteg. Fler intressanta koncept för framtida bearbetningsalternativ finns att studera i rapportens resultat och diskussionskapitel.
This master thesis report was performed at Linköpings University in cooperation with Scania Transmission in Södertälje and deals with specification of surface textures and processes for hard part machining of cogwheels and shafts. Present blueprints only include requirements for Ra-values, arithmetic mean deviation of the roughness profile (R-profile). Suggestions of new parameters according to SS-EN ISO standards used by Scania have been compiled with the aim of providing a more accurate description of the surface texture that is to be achieved. The result can be applied in general but are focused towards holes of cogwheels, planes and diameters. Furthermore a comparison between different methods is presented so that the transmission workshops can manufacture cogwheels and shafts in a costefficient manner. The work is based on a comparative literature study of handbooks and standards with complementary documentation of the present situation through collecting of measurements. A reference analysis and a few manufacturing tests of hard turning have also been performed. In difference from the present situation a transition from providing Ra-values on the blueprints to specify an upper limit for Rz-value to restrict the amplitude is recommended. Surfaces in relative motion and surfaces in heavy force fit are suggested to be complemented with a lower limit for Rz-values and a lower limit for relative material ratio. With an introduction of material ratio requirements the profiles distribution are also specified. Denunciation of manufacturing method and surface lay if any is suggested to be stated en clair on the blueprint being so that parameters describing characteristic features for different manufacturing methods have shown a wide range of distribution in the present state analysis. Comparison of hard part machining methods have shown that in combination machines, hard turning and grinding, solely hard turning of the cogwheels slide bearing surfaces would be interesting, which also seems plausible due to manufacturing samples and the reference analysis. After approved rigg tests this method can be adopted as a first step of optimization. More interesting concepts for future manufacturing alternatives are provided in the reports result and discussion chapters.
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Pacella, Manuela. "Pulsed laser ablation (PLA) of ultra-hard structures : generation of damage-tolerant freeform surfaces for advanced machining applications." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/27730/.
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The current methods for manufacturing super-abrasive elements result in a stochastic geometry of abrasives with random three-dimensional abrasive spatial locations. This thesis covers the laser generation of novel micro-cutting arrays in ultra-hard super-abrasive composites (e.g. polycrystalline diamond, PCD and polycrystalline cubic boron nitride, PCBN). Pulsed laser ablation (PLA) has been used to manufacture repeatable patterns of micro cutting/abrasive edges onto micro structurally different PCD/PCBN composites. The analysis on the influence of microstructural factors of the composite materials in the use of laser ablation technology has been carried out via a novel technique (Focused Ion Beam/High Resolution Transmission Electron Microscopy/Electron Energy Loss Spectroscopy) to identify the allotropic changes occurring in the composite as a consequence of PLA allowing the laser ablated PCD/PCBN surfaces to be characterized and the nanometric changes evaluated. The wear/failure characteristics/progression of the ultra-hard laser generated micro cutting/abrasive arrays has been studied in wear tests of Silicon Dioxide workpiece shafts and the influence of the microstructural factors in the wear properties of the super-abrasive micro cutting edges has been found. Opposing to these highly-engineered microcutting/abrasive arrays, conventional electroplated abrasive pads containing diamond and CBN abrasives respectively have been chosen as benchmarks and tested under the same conditions. Contact profiling, Optical Microscopy and Environmental Scanning Electron Microscopy have been employed for the characterization of the abrasive arrays/electroplated tools before/during/after the wear/cutting tests. In the PCD abrasive micro-arrays, the type of grain and binder percentage proved to affect the wear performances due to the different extents of compressive stresses occurring at the grain boundaries. In this respect, the micro-arrays made of PCD with mixed diamond grains have shown slower wear progression when compared to the electroplated diamond pads confirming the combination of the high wear resistance typical of the fine grain and the good shock resistance typical of the coarse grain structures. While PCD laser manufactured arrays indicated edge break as typical wear mechanism, the abrasive pad confirmed flattening of grits as main wear mechanism. Mixed grained PCD arrays performed 25% better than fine grained arrays. The improved wear performances of laser manufactured arrays when compared to industrial benchmark is proved by the different wear failure mechanism in the array and in the electroplated pad: in the first one the edges break creating new sharp edges during testing, while in the latter grit flattening is the main wear mechanism. This increases up to 60% the life of the laser manufactured array when compared to the benchmarked pads. As for the PCBN abrasive micro-arrays, two are the main wear mechanisms experienced by the arrays: edge flattening for the high CBN content array and edge breaking for the medium CBN content array. The wear performance of the high content PCBN array is directly comparable to the electroplated boron nitride pad, because they both worn out with edge/grit flattening. The increase of metallic binder and the presence of metalloids in the medium content-CBN specimens have shown to produce higher contact pressure with the workpiece when compared to the electroplated specimen, causing fracturing as the main wear mechanism; while the PCBN micro-array with purely a metallic binder phase has shown better wear performances and lower contact pressure in comparison to the electroplated CBN specimen. In particular, the laser manufactured array proved to perform 50% better than the electroplated ones in terms of wear resistance. Among all of the tested arrays, the mixed grained PCD and the purely metallic binder phase PCBN micro-arrays have shown slower wear when benchmarked to the electroplated pads, giving a possible application of their use in the cutting tool industry.
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Raghavan, Satyanarayanan. "Laser-based hybrid process for machining hardened steels." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47550.
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Cost-effective machining of hardened steel (>60 HRC) components such as a large wind turbine bearing poses a significant challenge. This thesis investigates a new laser tempering based hybrid turning approach to machine hardened AISI 52100 steel parts more efficiently and cost effectively. The approach consists of a two step process involving laser tempering of the hardened workpiece surface followed by conventional machining at higher material removal rates using lower cost ceramic tooling to efficiently cut the laser tempered material.
The specific objectives of this work are to: (a) study the characteristics of laser tempering of hyper-eutectoid 52100 hardened steel, (b) model the laser tempering process to determine the resulting hardness, and (c) conduct machining experiments to evaluate the performance of the laser tempering based hybrid turning process in terms of forces, tools wear and surface finish.
First, the microstructure alterations and phase content in the surface and subsurface layers are analyzed using metallography and x-ray diffraction (XRD) respectively. Laser tempering produces distinct regions consisting of - a tempered white layer and a dark layer- in the heat affected subsurface region of the workpiece. The depth of the tempered region is dependent on the laser scanning conditions. Larger overlap of laser scans and smaller scan speeds produce a thicker tempered region. Furthermore, the tempered region is composed of ferrite and martensite and weak traces of retained austenite (~ 1 %).
Second, a laser tempering model consisting of a three dimensional analytical model to predict the temperature field generated by laser scanning of 52100 hardened steel and a phase change based hardness model to predict the hardness of the tempered region are developed. The thermal model is used to evaluate the temperature field
induced in the subsurface region due to the thermal cycles produced by the laser scanning step. The computed temperature histories are then fed to the phase change model to predict the surface and subsurface hardness. The laser tempering model is used to select the laser scanning conditions that yield the desired hardness reduction at the maximum depth. This model is verified through laser scanning experiments wherein the hardness changes are compared with model predictions. The model is shown to yield predictions that are within 20 % of the measured hardness of the tempered region.
Using the laser scanning parameters determined from the laser tempering model, cutting experiments using Cubic Boron Nitride (CBN) tools and low cost alumina ceramic tools are conducted to compare the performance of laser tempering based hybrid turning with the conventional hard turning process. The machining experiments demonstrate the possibility of higher material removal rates, lower cutting forces, improved tool wear behavior, and consequently improved tool life in the laser tempering based process. In addition, the laser tempered based hybrid turning process produce is shown to yield lower peak-to-valley surface roughness height than the conventional hard turning process. Furthermore, it is found that lower cost ceramic tools can be used in place of CBN tools without compromising the material removal rate.
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Jílek, Bohumil. "Výroba vstřikovací formy." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228550.
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This thesis is focused on a production of injection molds. It contains some analyses of the various parts of the injection molds, a description of their functions and the possibility of structural design. A summary of existing technologies for the production of these molds, their advantages and disadvantages is included. This thesis deals with design of the component parts for injection of plastics, strategy of machining and a simulation of machining.
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Tropp, Pavel. "Vysokorychlostní obrábění ložisek z materiálu 100Cr6." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231982.
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This Master's thesis deals with the issue of high-speed turning of the 100Cr6 material. The aim is to identify and experimentally validate an innovative production process for a particular component. The thesis includes theoretical basis of high-speed machining, analysis of the current state of the manufacturing process, innovation design and experimental verification. At the end of the thesis, parameters of the machined surfaces of specimens are evaluated.
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Sousa, Taíse Azevedo de. "Usinagem de ferro fundido vermicular com ferramenta de corte à base de alumina magnésio /." Guaratinguetá, 2020. http://hdl.handle.net/11449/192492.
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Orientador: Marcos Valerio RibeiroResumo: The development of new materials is extremely important, due to the need to obtain materials with good properties and low cost. There is a continuing need to improve tools for machining materials that have high strength at elevated temperatures that meet the vermicular cast iron. Small advances in the development of new tools could mean important aspects in the field of machining, in addition to making the market more competitive. The set of production and application of ceramic cutting tools in the machining processes of vermicular cast iron (GJV450) needs further advances, being an object of great industrial interest. In this context, the present work determined the best application condition of the ceramic tools based on Alumina (Al2O3), doped with magnesium oxide (MgO) on a laboratory scale, in the machining without cutting fluid of the vermicular iron class GJV450 in comparison with a commercial carbide tool coated with alumina, based on the need for machining vermicular cast iron in industries and foundries. For turning vermicular cast iron with a ceramic tool, the parameters used were cutting speeds of 300-350-400-450-500-550-600-650 m / min; feed of 0.1-0.3 mm / rev and machining depth of 0.5 -1.0 mm and for the carbide tool, cutting speeds of 150-250-350-450 m / min; feed rate of 0.1-0.3 mm / rev and machining depth of 0.5 -1.0 mm. The previously defined input variables (Vc, f, ap), were correlated with the output variables such as roughness (Ra and Rt), power, acous... (Resumo completo, clicar acesso eletrônico abaixo)
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Šenkýř, Pavel. "Trendy vývoje obráběcích strojů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228222.
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This diploma thesis deals with trends of the development of machine tools, and focuses on technologies and machine tools for manufacturing of pressing dies and on manufacturing of cavity of moulds. First, the existing state in the field of these technologies is described and defined, and subsequently, the dissertation concentrates on modern conceptions of this manufacturing.
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Araujo, Juliano Bezerra de. "Desenvolvimento de método de avaliação de desempenho de processos de manufatura considerando parâmetros de sustentabilidade." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18140/tde-02032010-141958/.
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As empresas não mais podem pensar em desenvolvimento econômico sem a paralela preservação do meio-ambiente e do benefício mútuo da sociedade. É importante que as condições econômicas e sociais sejam melhoradas ao longo do tempo, sem exceder a capacidade de suporte do planeta. As indústrias podem contribuir para melhorar esse cenário aplicando uma gestão sustentável de manufatura, uma vez que estes são um dos principais agentes causadores de impactos. No entanto, para que consigam aprimorar a sustentabilidade de seus processos, é indispensável, antes de tudo, conhecer o seu real desempenho. O presente trabalho tem como objetivo principal desenvolver um método estruturado e simples para a avaliação de desempenho em sustentabilidade de processos de manufatura, permitindo a construção de relatórios de sustentabilidade mais precisos, periódicos e que venham a apoiar o processo de tomada de decisão gerencial. Embora modelos para a avaliação de desempenho em sustentabilidade tenham sido apresentados nos últimos anos, como o guia GRI, estes ainda carecem de critérios e regras para realizar análises mais precisas e integradas. O método proposto pode ser aplicado em dois processos de manufatura distintos, comprovando a sua eficácia e robustez. Ele é usado para analisar e comparar o desempenho em sustentabilidade de dois processos de usinagem, Retificação e Torneamento de Metais Endurecidos. Esses processos concorrem entre si em algumas faixas de atuação, tornando difícil a decisão sobre qual dos dois processos é o ideal para a produção de determinadas peças. Por meio do trabalho, foi possível comprovar a superioridade do processo de retificação em termos de ganhos econômicos, com a contrapartida de pior desempenho ambientalCompanies can no longer consider economical development without the parallel preservation of the environment and mutual benefit of the society. It is important that the economic and social conditions are improved over time, without exceeding the planet carrying capacity. Industries can contribute to improve this scenario by using cleaner and more efficient technologies, since they are one of the main sources of impacts. However, for them to improve their processes sustainability, it is essential to use an assessment tool which is able to evaluate their performance properly. The main goal of this work is to provide a structured and simple method for assessing sustainability performance of manufacturing processes, allowing the construction of more accurate and frequent sustainability reports, that may support the managerial decision making process. Although sustainability performance assessment models have been presented in recent years, as the GRI, there are still a lack of criteria and rules for carrying out more accurate and integrated assessments. The proposed method was able to be applied in two different manufacturing processes assessments, proving its effectiveness and robustness. It was used to analyze and compare the sustainability performance of two machining processes, grinding and hard turning. These processes compete with each other on some applications, making it difficult to decide which of the two processes is ideal for the production of certain parts. Through the study, it is demonstrated the grinding process superiority in terms of economic gains, at the cost of a higher environmental burden
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Bukáček, Zdeněk. "Technologie obrábění tvrdých materiálů nástroji s definovanou geometrií břitu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228640.
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This master’s thesis is concerned with subject matter hard machining with defined geometry edge tools. Aim master’s thesis is analysis and parameters evaluation machined surface at hard machining. This master’s thesis contain a characteristic of hard materials, used technology for cutting operation, but also tools and cutting conditions suitable for hard machining. In the conclusion are parameters evaluation machined surface the workpiece.
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Alves, Guilherme Carlos. "Estudo experimental de lubrificação e resfriamento no torneamento duro em componentes de grande porte." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18156/tde-11102017-140716/.
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Este trabalho teve como objetivo o estudo experimental de lubrificação e resfriamento no torneamento duro de uma superfície funcional em componentes de grande porte, com aplicação no chão de fábrica. Foram comparadas as técnicas de mínima quantidade de lubrificante e resfriamento abundante, utilizando o método de resposta de superfície. O planejamento tridimensional utilizado foi de dois níveis, adicionado de pontos axiais, ponto central e de réplica. Foram variados a velocidade periférica da peça, o avanço da ferramenta de usinagem e a profundidade de usinagem. Após a execução do experimento, a integridade da superfície foi analisada pela medição da tensão residual, da espessura de possíveis modificações microestruturais e pela medição dos parâmetros estatísticos Sa, Sq e Sz. As medidas foram então ajustadas em modelos matemáticos, otimizadas e por fim comparadas. A análise dos resultados sinalizou que os modelos ajustados para ambos os métodos foram capazes de explicar satisfatoriamente o comportamento das variáveis de resposta. Ainda, a partir da função desirability, foi possível estimar valores ótimos com qualidade equivalente entre os métodos. Tanto para o emprego com mínimas quantidades quanto para resfriamento abundante foram registradas tensões circunferenciais altamente compressivas. Nas condições ótimas, quando empregadas mínimas quantidades de lubrificante, a superfície apresentou valores de tensões residuais 37% maiores em comparação ao obtido quando empregado o resfriamento abundante. Ambos os métodos produziram tanto superfícies livres de modificações microestruturais significativas, como também superfícies com modificações microstruturais significativas. Porém, quando detectadas, as modificações se mostraram muito reduzidas, com espessura de até 2,35 μm. Nas condições ótimas, quando empregado mínimas quantidades de lubrificante, a espessura da modificação foi 74% menor em comparação ao obtido quando empregado o resfriamento abundante. Os parâmetros estatísticos sugeriram alguma vantagem da aplicação de mínimas quantidades de lubrificante. Nas condições ótimas, a aplicação MQL apresentou melhor rugosidade Sa, em 47%, e Sz, em 11%. Porém, o desvio-padrão Sq da superfície apresentou valor 12% maior ao resfriamento abundante.This work aimed to conduct a study of cooling and lubrication in hard turning of functional surface of large components. It was compared the performance of minimum quantity lubrication and abundant cooling through the application of response surface methodology. The activities were developed in shop floor application. It was designed a three-dimensional experiment with two levels, added by axial points, center point and one center replicate. The input variables were the peripheral velocity of the workpiece, the feed of the cutting tool and the depth of cut of machining. After the process were analyzed the surface integrity through the circumferential residual stress, possibly microstructure modified layers and statistical parameters such Sa, Sq and Sz. Then, the measurements were adjusted in mathematical models, optimized and compared. The analysis of the results indicated that the adjusted models for both methods were capable of explaining satisfactorily the behavior of the response variables. Also, the use of the desirability function allowed to predict optimal values with equivalent quality between the methods. The minimal quantities, as well the abundant cooling, produced circumferential residual stresses highly compressive. On optimal conditions, the MQL presented residual stresses 37% lower the abundant cooling. Both methods produced surfaces free of significant altered layers as well surface containing significant surface altered layer. However, when detected, the altered surface layer was very thin, with thickness up to 2,35 μm. On optimal conditions, the MQL altered layer was 74% lower the abundant cooling. The statistical parameters indicated some advantage on the application of MQL. On optimal conditions, the minimal quantities presented better Sa roughness in 47%, and Sz, in 11%. However, the standard deviation Sq of the surface presented a value 12% higher the abundant cooling.
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Baizeau, Thomas. "Développements expérimentaux et numériques pour la caractérisation des champs cinématiques de la coupe de l’acier 100 CrMo 7 durci pour la prédiction de l’intégrité de surface." Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0054/document.
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Aujourd'hui, les méthodes de corrélation d'images sont largement utilisées pour la caractérisation et le suivi temporel des essais mécaniques. Cependant dans le domaine de l'usinage, ces méthodes sont très peu employées pour l'étude en pointe d'outil de la coupe par manque d'accessibilité, de la faible taille de la zone observée et des fortes déformations dans la zone de coupe. Dans cette thèse, nous mettons en application la technique de corrélation d'images pour l'étude et la caractérisation des champs cinématiques induits dans la matière usinée, durant des essais de coupe conduits avec des conditions opératoires représentatives des opérations industrielles. Ces conditions nous ont permis de développer, en premier lieu, des outils expérimentaux et numériques. Puis, les performances du dispositif expérimental ainsi que les incertitudes de corrélation ont été quantifiées. Différentes stratégies d'exploitation des images ainsi que des outils numériques pour la mesure des caractéristiques de la coupe sont proposés. Ensuite, nous avons développé un outil de corrélation d'images intégrée pour la mesure des efforts dynamiques grâce à un modèle analytique. Pour valider l'ensemble des méthodes, des essais de rabotage, d'abord dans un alliage d'aluminium, puis dans un acier 100~CrMo~7 traité thermiquement, ont été conduits. Ils ont permis de quantifier les champs cinématiques ainsi que les caractéristiques de la coupe. Enfin ces outils ont été appliqués pour la prédiction de l'intégrité de surface engendrée par une géométrie 3D d'outil de coupe dans le matériau durNowadays, digital image correlation (DIC) methods are widely employed to the mechanical testing characterization and their temporal monitoring. However in the machining field, to study the cutting process at the tool edge, these methods are not commonly applied due to the poor accessibility, the size of the observed area and the large strain occurring herein. In this study, the kinematic fields induced in the material by the cutting process are characterized and analyzed at industrial cutting conditions. In order to take and treat the pictures of the cut, experimental and numerical techniques have been first established. Then, the experimental setup performances and the uncertainties of the DIC were quantified. Different images selection strategies for the DIC and numerical post-processing algorithm for measuring the characteristics of the cut were proposed. Furthermore, a DIC integrated approach based on an analytical model was developed to record dynamics cutting forces. Trials in orthogonal configuration were performed and analyzed to validate the developed procedures first in an aluminium alloy, then in a 100~CrMo~7 hardened steel. The kinematics fields and the macroscopic data of the cut were successfully measured thanks to these tools. Finally, they were used for the prediction of the surface integrity induced by a 3D cutting edge in the hard material
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Filípek, Timotej. "Obrábění těžkoobrobitelných materiálů dokončovacími technologiemi." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444264.
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The Master‘s thesis focuses on processing of hard-to-machine materials by the finishing machining methods. The first chapter comprises division and characteristics of finishing technologies in the field of machining processes. The chapter following includes division and characteristics of the hard-to-machine materials. The experimental part – another significant part of the thesis – is focused on grinding of mostly bearing rings made of hard-to-machine materials. The aim of the experimental part is to compare and subsequently assess the use of various kinds of grinding wheels in the grinding process of a given workpiece material. Several parameters are examined from the technological and economic point of view. The assessment of the experimental part provides an overview on the advantages and disadvantages of the use of the grinding wheels in the grinding process of a given material for large-scale production. The conclusion is a summary of the results obtained in the experimental part.
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Salazar, Carlos Eddy Valdéz. "Avaliação através da inspeção magnética da condição superficial de anéis de rolamento de aço DIN 100Cr6 após torneamento duro a seco." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-11052009-174233/.
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O presente trabalho visa apresentar informações que viabilizem a fabricação de componentes de rolamentos com limites superiores de resistência à fadiga, com a intenção de proporcionar uma vida útil maior ao rolamento, e, também, a otimização da fabricação das peças, dispensando em alguns casos o processo final e usual de retificação, o que implica uma redução de custos. As motivações deste estudo são a geração de altas tensões residuais compressivas no torneamento duro-seco a altas velocidades, a aplicação do RMB como técnica de medição das tensões residuais em aço 100CrMn6 e a otimização da qualidade/custos na fabricação de rolamentos. Para atingir essas metas, será estudada a influência dos parâmetros da usinagem (velocidade de corte (Vc), avanço (a), penetração (p) e desgaste da ferramenta (VB)) na geração das tensões residuais superficiais (sR) e sobre as forças de torneamento (Fc, Fa, Fp), em anéis internos de rolamentos cônicos de aço DIN 100CrMn6 endurecidos termicamente, procurando-se estabelecer uma correlação entre o desgaste da ferramenta e os referidos esforços e tensões residuais. Na etapa experimental, será utilizado um planejamento fatorial completo para executar os ensaios e medições projetadas. No ensaio de torneamento, serão medidas as forças de corte utilizando-se, para isso, um dinamômetro piezoelétrico. Em seguida, serão efetuadas medições de rugosidade. Também será realizado o estudo da microestrutura através da análise metalográfica. As tensões residuais serão medidas utilizando-se o método do furo-cego com extensometria elétrica, e as medidas das alterações microestruturais superficiais serão realizadas pela técnica do Ruído Magnético de Barkhausen (RMB). Serão correlacionados os valores de tensão residual obtidos pela técnica do furo com o RMB.The present work presents information for the manufacturing of ball bearings components with higher limits of resistance to fatigue, enabling a longer useful life and also the optimization of the production of the pieces, making the usual and final process of grinding unnecessary, which would result in a costs reduction. The motivations of this study are the generation of compressive high residual stress in the hard-dry turning at high speeds, the application of the MBN as technique of measurement of the residual stress in steel 100CrMn6, and the optimization of the quality/costs in the manufacturing of ball bearings. In order to achieve these purpose, the work will study the influence of the machining parameters (cutting speed (Vc), feed rate (a), depth of cut (p), and wear of tool (VB)) in the generation of the superficial residual tensions and also the turning forces (Fc, Fa, Fp), in internal conical rings of ball bearings of steel 100CrMn6 thermally hardened, seeking to find a correlation between the stress of the tool and the referred efforts. In the experimental phase, a complete factorial planning will be used to perform the tests and measurements projected. In the turning tests, the cutting forces will be measured using a piezoelectric dynamometer. After that, measurements of superficial roughness will be performed. Also, the study of the microstructure will be made through the metallographic analysis. The residual tensions will be measured using the strain gage hole-drilling method and the measurement of the superficial microestrutural alterations will be carried out using the technical of the magnetic Barkhausen noise (MBN). The values of residual tension obtained by the hole-drilling will be correlated with the RMB.
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Klika, Jiří. "Ruční pracovní nářadí pro renovační účely." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378864.
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Diploma thesis deals with renovation of tractor Zetor 6911 with hand tool machining use. Theoretical part aims at historical evolution of machining and describes the hand tool machining methods. Renovation options include repair by a renovation company, yourself renovation and yourself renovation with cooperation in external company. Due to great renovation experience and technical knowledge is tractor chosen to be renovated by yourself. Complete machine renovation is very complex thus there are shown only specified examples of machine parts renovation. In the thesis there are in detail described renovation processes, including tools and hand devices. Final part includes results evaluation and costs comparation of renovation options.
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Nabhani, Farhad. "The performance of ultra-hard cutting tool materials in maching aerospace alloy TA48." Thesis, University of Hull, 1991. http://hydra.hull.ac.uk/resources/hull:4627.
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A study has been made of the respective performance of cubic boron nitride (CBN) and polycrystalline diamond (PCD) cutting tool materials and compared to various coated and uncoated tungsten carbide grades when cutting titanium alloy workpieces. Two important experimental techniques were employed during the course of this work, firstly a quasi-static contact method was employed to establish the workpiece/tool interfacial temperature above which strongly adherent layers may be formed. This technique revealed that the critical temperatures which marked adhesion and welding, were 740, 820 and 800 °C for coated and uncoated carbides, and 760 and 900 °C for PCD and CBN tools respectively. Furthermore, the technique has been used to study the integrity of the bulk tool material, and/or individual coatings on their substrates, when welded junctions formed between the tool and workpiece are separated. With regard to the latter it was observed that in all cases fracture was initiated in the bulk of the harder tool material rather than in the workpiece or at the welded junction interface. Secondly, a quick-stop technique was used to study chip formation and tool wear when cutting with carbides, CBN and PCD tools under nominally the same conditions. The predominant wear mechanisms for each of the tool materials was found to be based on a diffusion/dissolution process. The wear process is discussed in detail for each of the tool materials and reasons advanced for observed differences in performance when removing material from a titanium alloy workpiece. The wear resistance and quality of the machined surface was found to be superior when cutting with the ultra-hard materials than with the carbide grades and in particular the PCD tool was found to produce exceptionally good surface finish. In the case of coated carbide tool grades rapid removal of the coated layers occurred leaving the substrate vulnerable to reaction with the workpiece material and this is considered to explain the seeming absence of beneficial effects when cutting with these grades.
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Calamba, Katherine. "Phase stability and defect structures in (Ti1-x,Alx)Ny hard coatings." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0322.
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Cette étude met en évidence le rôle des lacunes d’azote et des défauts structuraux dans l’ingénierie de revêtements durs à stabilité de phase améliorée et dont les propriétés mécaniques sont compatibles avec des applications à haute température. Le nitrure de titane et d’aluminium (Ti,Al)N sous forme de revêtements est un matériau de choix pour la protection des outils de coupe pour métaux en raison de sa résistance supérieure à l’oxydation et à l’usure à haute température. La décomposition spinodale à haute température de la phase métastable cubique (Ti,Al)N en domaines cohérents de taille nanométrique de c-TiN et de c-AlN donne une dureté importante aux températures élevées. Un apport thermique encore plus élevé conduit à la transformation de c-AlN en w-AlN, ce qui nuit aux propriétés mécaniques du revêtement. Un moyen de retarder cette transformation est d'introduire des lacunes d'azote. Dans cette thèse, je montre que la combinaison d’une réduction de la teneur globale en azote du revêtement c-(Ti,Al)Ny(y <1) avec une faible tension de polarisation du substrat lors du dépôt par arc cathodique induit un retard encore plus prononcé de la transformation de la phase c-AlN en w-AlN. Dans de telles conditions, le durcissement par vieillissement est conservé jusqu'à 1100 ° C, ce qui correspond à la température la plus élevée signalée pour les films de (Ti,Al)N. Au cours des opérations de coupe, le mécanisme d'usure des films c-(Ti0.52Al0.48)Ny déposés par arc cathodique avec des teneurs en N de y = 0.92, 0.87 et 0.75 est influencé par l'interaction des lacunes d'azote, de la microstructure et des réactions chimiques avec le matériau de la pièce. Le revêtement y = 0.75 contient le plus grand nombre de macroparticules et présente, après usinage, une microstructure non homogène qui en abaisse la résistance à l'usure sur les flancs et les cratères. Le durcissement par vieillissement de l'échantillon y = 0.92 entraîne une résistance supérieure à l'usure sur le flanc, tandis que la structure dense de l'échantillon y = 0.87 empêche l'usure chimique qui se traduit par une excellente résistance à l'usure sur les cratères. Des films hétéroépitaxiés c-(Ti1-x, Alx)Ny (y = 0.92, 0.79 et 0.67) ont été déposés sur des substrats de MgO(001) et (111) en utilisant une technique de pulvérisation magnétron pour examiner en détail les défauts structuraux pendant la décomposition spinodale. À 900 °C, les films se décomposent pour former des domaines cohérents riches en c-AlN et c-TiN de forme allongée le long de la direction <001>. Les cartographies de déformation montrent que la plupart des contraintes se trouvent près de l'interface des domaines ségrégés et à l'intérieur des domaines c-TiN. Les dislocations s'agrègent favorablement dans c-TiN plutôt que dans c-AlN car ce dernier a une directionnalité plus forte des liaisons chimiques covalentes. À température élevée, la taille de domaine des films de c- (Ti, Al)Ny orientés (001) et (111) augmente avec la teneur en azote. Cela indique qu'il y a un retard dans le grossissement dû à la présence de plus de lacunes d’azote dans le film. [...]This study highlights the role of nitrogen vacancies and defect structures in engineering hard coatings with enhanced phase stability and mechanical properties for high temperature applications. Titanium aluminum nitride (Ti,Al)N based materials in the form of thin coatings has remained as an outstanding choice for protection of metal cutting tools due to its superior oxidation resistance and high-temperature wear resistance. High-temperature spinodal decomposition of metastable (Ti,Al)N into coherent c-TiN and c-AlN nm-sized domains results in high hardness at elevated temperatures. Even higher thermal input leads to transformation of c-AlN to w-AlN, which is detrimental to the mechanical properties of the coating. One mean to delay this transformation is to introduce nitrogen vacancies. In this thesis, I show that by combining a reduction of the overall N-content of the c-(Ti,Al)Ny (y < 1) coating with a low substrate bias voltage during cathodic arc deposition an even more pronounced delay of the c-AlN to w-AlN phase transformation is achieved. Under such condition, age hardening is retained until 1100 °C, which is the highest temperature reported for (Ti,Al)N films. During cutting operations, the wear mechanism of the cathodic-arc-deposited c-(Ti0.52Al0.48)Ny with N-contents of y = 0.92, 0.87, and 0.75 films are influenced by the interplay of nitrogen vacancies, microstructure, and chemical reactions with the workpiece material. The y = 0.75 coating contains the highest number of macroparticles and has an inhomogeneous microstructure after machining, which lower its flank and crater wear resistance. Age hardening of the y = 0.92 sample causes its superior flank wear resistance while the dense structure of the y = 0.87 sample prevents chemical wear that results in excellent crater wear resistance. Heteroepitaxial c-(Ti1-x,Alx)Ny (y = 0.92, 0.79, and0.67) films were grown on MgO(001) and (111) substrates using magnetron putter deposition to examine the details of their defect structures during spinodal decomposition. At 900 °C, the films decompose to form coherent c-AlN- and c-TiN- rich domains with elongated shape along the elastically soft <001> direction. Deformation maps show that most strains occur near the interface of the segregated domains and inside the c-TiN domains. Dislocations favorably aggregate in c-TiN rather than c-AlN because the later has stronger directionality of covalent chemical bonds. At elevated temperature, the domain size of (001) and (111)- oriented c-(Ti,Al)Ny films increases with the nitrogen content. This indicates that there is a delay in coarsening due to the presence of more N vacancies in the film. The structural and functional properties (Ti1-x,Alx)Ny are also influenced by its Al content (x). TiN and (Ti1-x,Alx)Ny (y = 1, x = 0.63 and x = 0.77) thin films were grown on MgO(111) substrates using magnetron sputtering technique. Both TiN and Ti0.27Al0.63N films are single crystals with cubic structure. (Ti0.23,Al0.77)N film has epitaxial cubic structure only in the first few atomic layers then it transitions to an epitaxial wurtzite layer, with an orientation relationship of c-(Ti0.23,Al0.77)N(111)[1-10]ǀǀw-(Ti0.23,Al0.77)N(0001)[11-20]. The w-(Ti0.23,Al0.77)N shows phase separation of coherent nm-sized domains with varying chemical composition during growth. After annealing at high temperature, the domains in w-(Ti0.23,Al0.77)N have coarsened. The domains in w-(Ti0.23,Al0.77)N are smaller compared to the domains in c-(Ti0.27,Al0.63)N film that has undergone spinodal decomposition. The results that emerged from this thesis are of great importance in the cutting tool industry and also in the microelectronics industry, because the layers examined have properties that are well suited for diffusion barriers
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CHAN, YI-CHU, and 詹易築. "Ultrasonic micro machining hard and brittle materials." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/88058944575226194193.
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碩士國防大學中正理工學院
兵器系統工程研究所
90
Abstract Ultrasonic machining (UM) is considered to be a very effective and relatively accurate way to engrave fine patterns and drill holes on brittle materials. This study aimed to investigate the feasibility of utilizing UM technique to fabricate parts of brittle materials in micrometers scale. Although brittle fracture (micro chipping) is the dominant material removal mechanism involved in the m-UM process, poor surface roughness and deep penetrated cracks are the consequences if the machining parameters are not properly controlled. To ensure the quality of the generated surface and to improve the process efficiency, efforts have been made in this study to correlate the material removal mechanisms; surface integrity and tool wear involved in the μ-UM process to the machining conditions. The ultrasonic vibration frequency was kept at 20 kHz and the feedrate was kept between 0.5 mm/min to 0.1 mm/min. The effects of machining parameters such as types of abrasives, grit sizes and feedrates were investigated. It is found that by dividing the machining process into several stages, from coarse to fine, good surface integrity can be achieved without surrendering too much efficiency. Micro-components of various brittle materials such as glasses, Zerodur, fused quartz and silicon with dimension smaller than 100mm and surface roughness better than 0.15mm were successfully produced in this study.
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Tong, Guan-Min, and 童冠敏. "A Study on Machining Texture Applied to Machine Tool Hard Rail." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/12860368027647731596.
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碩士國立中興大學
機械工程學系所
103
Hard rails are usually employed for feeding system of heavy load and heavy-duty machine tools. While hard rail requires lubrication on the contact surfaces scraping is applied to allow lubricant flow into the interface. However, the characteristics of such feeding system is hard to control because of the quality of manual scraping varies depending on the craftsmen’s skill as the technique is inherited between masters and apprentices. Previous studies have revealed that friction characteristics are can be improved micro-structure textures fabricated on the friction surfaces by computer numerical controlled machining. However, the friction characteristics of such texture are not consistent, found from characteristic tests. This study is to design and to fabricate a new texture to improve the stability of friction characteristics in the reciprocating motions of feeding system. The major results achieved in this study can be summarized as follows. (1) Results of pilot experiments showed that the friction coefficient, based on previously designed textures, of forward and backward strokes are different in the reciprocating motion. (2) The friction characteristics of three types of manually scrapped blocks are close to that of manually scraped hard rail of a machine tool. The result showed that the friction coefficients of forward and backward strokes are stable, unless under the condition of low velocity and low pressure. (3) A new texture with new configuration of grooves is designed and tested. The results showed that the friction coefficient of the new texture is about the same as that of manual scrapping, in both value and stability. The results of this study revealed that, by comparison with manual scraping, the friction properties of the sliding blocks with new texture are on the same level. While the texture is machined by CNC machining, the quality and repeatability can be well controlled that overcomes the major drawback of manual scraping. This study also reveals that current manual scraping of hard rails can be replaced by this technology with better quality.
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Nguyen, Huu-That, and 阮友真. "Dynamics of Machine Tool and Optimization of Machining Parameters in Hard Milling." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/v4e865.
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博士國立高雄應用科技大學
機械工程系
105
Nowadays, in order to enhance performance and product quality in the mold and die manufacturing industry, the finishing grinding process is often replaced by a hard milling operation; this way, the product cycle time can be decreased, productivity increased, and the quality of finished products can be significantly improved. In this study, an attempt is made to analyze the effect of process parameters on cutting force components, surface roughness and material removal rate (MRR) in the hard milling of SKD 61 steel based on a combination of the Taguchi method and Response surface methodology (RSM). The machining process parameters are selected based on the structural dynamic analysis of the milling machine tool. A set of experiments is designed according to the Taguchi technique. The cutting force values are measured by a Dynamometer. The average surface roughness is measured by a Mitutoyo Surftest SJ-400. And then, analysis of variance (ANOVA) is performed to determine the influences of the cutting process parameters on the given response characteristics. Quadratic mathematical modeling is introduced for predicting the cutting forces, surface roughness and MRR during the hard milling process. Predicted values obtained from the developed model and experimental results are compared, and it shows that the predicted values are in reasonable consensus with the observation of experiments. In an effort to obtain the small cutting forces and surface roughness and large MRR, a simultaneous objective optimization is employed based on the desirability function. The results show that the percentage error between measured and predicted values of surface roughness and MRR are 9.84 % and 2.27 %, respectively. In addition, the percentage error between measured and predicted values of the cutting force components (Fx, Fy, and Fz) are found to be (8.78, 7.46 and 9.53) %, respectively, which is found to be small. Eventually, the milled surface roughness under the optimized machining parameters is 0.193 µm, which can be justified so that the finish hard milling is able to replace the finish grinding in the mold and die manufacturing industry. Therefore, the RSM could be effectively applied to optimize simultaneously some response characteristics during the hard milling process of JIS SKD 61 alloy steel.
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MIN, LIN CHIEN, and 林建民. "Construction Technology of High Hard, High Brittleness of Tungsten via Wire Electrical Discharge Machining Process." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/08903125110470753860.
Full textAbstract:
碩士明新科技大學
精密機電工程研究所
102
This study analyzed variation of metal removal rate, workpiece surface finish and depending on WEDM process parameters during manufacture of pure tungsten profiles. A hybrid method including Taguchi method and response surface methodology (RSM) are proposed to determine an optimal parameter setting of the WEDM process. The specimens are prepared under different WEDM process conditions based on a Taguchi orthogonal array table. The results of eighteen experimental runs were utilized to analyze the metal removal rate (MRR) and the roughness average (Ra) properties at various WEDM process conditions, and then the Taguchi and RSM approaches were applied to individual search for an optimal setting. The results show that the Taguchi and the RSM methods are effective tool for the optimization of WEDM process parameters. In this study, the proposed algorithm of RSM approach has better prediction results than the Taguchi method. In addition, analysis of variance (ANOVA) was implemented to identify significant factors for the WEDM process parameters. Finally, a side-by-side comparison of different approaches (the Taguchi method, and the RSM approach) is also provided. The error percentage is within permissible limits.
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Guo, Jhe-liang, and 郭哲良. "Use of 5-Axis Machining Experiments to Study the Manufacturing Processes of Impeller with Very Hard Material." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/52297127273190481994.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
101
The applications for impellers in the aerospace industry and compressor industry are numerous. Its dimensional accuracy and processing efficiency are issues worthy of in depth research. This study uses five-axis machining experiments to perform an analysis concerning surface quality and processing performance of an impeller, material type SKD 61. During the experiments, feed rate, speed, and cut depth are used as variables, and this study finds the shortest time required for machining. Then, tool axis planning is performed to attain the objective of enhancing impellers' surface quality. In terms of an impeller's machining procedure, this study employs machining sequencing in the following order: groove roughing, blade semi-finishing, Hub Surface semi-roughing, blade finishing and Hub Surface finishing. Testing of machining parameters, connection of tool paths, and planning of tool orientations are undertaken for each of the machining steps. Through multiple 5-axis machining experiments, this study reaches the following conclusions: using an end mill can reduce the time required for roughing, while changes in tool orientations and connections of tool paths can eliminate the blade's surface roughness and enhance surface quality.
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Parker, Grant. "Self-propelled rotary tool for turning difficult-to-cut materials." Thesis, 2011. http://hdl.handle.net/10155/249.
Full textAbstract:
Hard turning of difficult-to-cut materials is an economical method of machining components with high surface quality and mechanical performance. Conventionally in the machining industry, generating a component from raw goods includes a casting or forging process, rough machining, heat treatment to a desired hardness, and then finished-machining through a grinding process. Given the relative disadvantages of grinding, which include high specific energy consumption and low material removal rates, a newer technology has been introduced; hard turning. After the heat treatment of a cast part (generally in a range of 50-65 HRC), hard turning allows for immediate finished-machining. Hard turning reduces the production time, sequence, cost, and energy consumed. In addition, dry machining offsets environmental concerns associated with the use of coolant in grinding operations as well as other common turning operations.
Higher specific forces and temperatures in the contact area between the tool and workpiece lead to excessive tool wear. Generated tool wear affects the quality of the machined surface. Therefore, minimizing tool wear and consequently the generated surface quality become the status quo. Adverse effects associated with generated heat at the tool tip can be reduced by using
cutting fluid or by continuously providing a fresh cutting edge. The latter method will be applied in this thesis.
Rotary tool cutting involves a tool in the form of a disk that rotates about its axis. Different types of rotary tools have been developed, all with similar functional characteristics, however few are commercially available. Rotary tools can be classified as either driven or self-propelled. The former is provided rotational motion by an external source while the latter is rotated by the chip flow over the rake face of the tool.
A prototype self-propelled rotary tool (SPRT) for hard turning was developed which provides economical benefits and affordability for the user. It was tested on a turret-type CNC lathe by machining AISI 4140 Steel that was heat treated to 54-56HRC and Grade 5 Titanium (Ti-6Al-4V). Carbide inserts with ISO designation RCMT 09 T3 00 (9.5mm diameter) were used during machining. Both the SPRT rotational speed and the workpiece surface roughness were measured. Also, chips were collected and analyzed for each of the cutting conditions. The same procedure was followed during machining with the same tool which was denied the ability to rotate, therefore simulating a fixed tool with identical cutting conditions. Comparisons were made between tool life, surface roughness, and chip formation for the fixed tool and SPRT. Tool rotational speed was also analyzed for the SPRT. In general, the designed and prototyped SPRT showed very good performance and validated the advantages of self-propelled rotary tools.
A typical automotive component that is hard turned from difficult-to-cut materials is a transmission input shaft. These components demand high strength and wear resistance as they couple the vehicle‟s engine power to the transmission and remaining driveline.UOIT
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Huang, Yao Yi, and 黃堯義. "The Determinants of Partnership between Customers and Suppliers: An Empirical Study of Taiwan Hand Tool Metal Machining Industry." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/xe4edw.
Full textAbstract:
碩士東海大學
高階經營管理碩士在職專班
104
Taiwan metal hand tool industry development patterns already achieved stably mature. And the machining costs will be influence by customers and enterprise as well as supplier cooperate partnership models This study aims to research what factors affect the following Taiwan formed up-down stream metal machining processing partnerships? First, If the nature of customer's strategy policy (low-cost strategy and variation strategy) influence customers and suppliers partnership? Second, If the nature of the transaction (exclusive asset, transaction frequency, uncertainty transaction) affect customers and suppliers partnership? Third, If the suppliers nature ability (cost, learning ability, cooperation ability ) influence the customers and suppliers partnership? In order to study this question, this research conducts the empirical research, take the Taiwan Metal hand tool industry as the study object by the questionnaire way on the 149 finally effective questionnaire results to carry on the regression analysis. The study results findings: (1) Transaction frequency positive influence the partnership (2) Uncertainty Transaction reverse influence partnership (3) The supplier learning capability positive influence the partnership However ,the supplier cooperation ability , customer's variation strategy and Exclusive transaction Asset no significant impact the partnership.
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Guimarães, Bruno Miguel Pereira. "Produção e caracterização de ferramentas de corte obtidas por tecnologia laser." Master's thesis, 2018. http://hdl.handle.net/1822/74205.
Full textAbstract:
Dissertação de Mestrado (Ciclo de Estudos Integrados Conducentes ao
Grau de Mestre em Engenharia de Materiais)A indústria das ferramentas de corte enfrenta atualmente grandes desafios uma vez que nos últimos anos, novos materiais com elevada dureza e baixa condutividade térmica estão, cada vez mais, a ser utilizados. Este panorama leva a que seja necessário desenvolver novas soluções usando materiais e processos de fabrico inovadores. A baixa condutividade térmica destes materiais resulta num rápido aumento da temperatura na zona de corte durante o processo de maquinagem induzindo assim uma taxa de desgaste rápida na ferramenta de corte, reduzindo a sua vida útil. Deste modo, a temperatura na aresta de corte desempenha um papel crucial durante o processo de maquinagem, procurando esta indústria novas formas para a reduzir eficazmente. A adição de materiais condutores à ferramenta de corte pode aumentar a sua condutividade térmica, permitindo reduzir a temperatura na aresta de corte e consequentemente o seu desgaste, aumentando o seu tempo de vida útil. Este trabalho consiste no desenvolvimento e produção de ferramentas de corte de metal duro (WC-Co) com canais de escoamento de calor que permitam aumentar a capacidade de extração de calor destas ferramentas. Este trabalho foi realizado em colaboração com a empresa PALBIT S.A. que pretende incorporar nas suas ferramentas de corte soluções que reduzam estes problemas. Inicialmente foram desenvolvidos vários designs para os canais de escoamento, cuja eficácia quanto à extração de calor foi aferida por via de simulação numérica. Partindo de compactos a verde, foi selecionada a tecnologia laser para a maquinagem dos canais de escoamento de calor, devido à versatilidade desta tecnologia. Após a maquinagem a laser estes compactos foram sinterizados e subsequentemente os canais de escoamento de calor foram preenchidos com materiais condutores. Os parâmetros de processamento utilizados na maquinagem a laser, especialmente a potência, velocidade de varrimento e espaçamento entre linhas, foram aferidos, uma vez que influenciam significativamente o processo de maquinagem, nomeadamente a qualidade do acabamento superficial, bem como a capacidade de remoção de material por parte do laser. A condutividade térmica das ferramentas desenvolvidas e produzidas foi obtida a partir da medição da resistividade elétrica a quatro pontos, usando a equação de Wiedemann-Franz. Os resultados mostraram que a adição de materiais condutores permite aumentar a condutividade térmica do metal duro em 110 e 130 % quando se adiciona cobre ou alumínio, respetivamente.
The cutting tool industry is currently facing major challenges as new materials with high hardness and low thermal conductivity are increasingly being used in recent years. This scenario leads to the need to develop new solutions using innovative materials and manufacturing processes. The low thermal conductivity of these materials results in a rapid increase in temperature in the cutting zone during the machining process, thereby inducing a rapid wear rate on the cutting tool, reducing its life time. In this way, the temperature at the cutting edge plays a crucial role during the machining process, seeking this industry new ways to effectively reduce it. The addition of conductive materials to the cutting tool can increase its thermal conductivity, allowing to reduce the temperature at the cutting edge and consequently its wear, increasing its life time. This work addresses the development and production of carbide cutting tools (WC-Co) having heat transfer channels to increase the heat extraction capacity of these tools. This work was performed in collaboration with the company PALBIT S.A., that intends to integrate in their cutting tools the solutions that allow to reduce the abovementioned problems. Initially, several designs were developed for the channels, whose efficiency in the extraction of heat was measured by means of numerical simulation. Starting from a green body, laser technology was selected for the machining of these heat transfer channels, due to the versatility of this technology. After laser machining, these compacts were sintered and subsequently the heat transfer channels were filled with conductive materials. The processing parameters used for the laser machining, especially the power, scanning speed and line spacing, were evaluated as they significantly influence the machining process, namely the surface finish quality as well as the ability of the laser to remove material. The thermal conductivity of the tools developed and produced was obtained by measuring the electrical resistivity at four points, using the Wiedemann-Franz equation. The results showed that the addition of conductive materials allows to increase the thermal conductivity of hard metal by 110 and 130% when copper or aluminum is added, respectively.
Este trabalho foi apoiado pela FCT através do projeto POCI-01-0145-FEDER-030353 (SMARTCUT), PTDC/EMS-TEC/5422/2014 (ADAPTPROSTHESIS) e também pelo projeto NORTE 01- 0145_FEDER-000018 (HAMaBICo). Além disso, este trabalho foi financiado pela FCT com o projeto de referência UID/EEA/04436/2013, por fundos FEDER através do COMPETE 2020-Programa Operacional Competitividade e Internacionalização (POCI) com o projeto de referência POCI-01-0145- FEDER-006941.