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Systém managementu měření / Measurement management systemAichler, Jaroslav January 2009 (has links)
The subject of diploma thesis is analysis of the European Standard EN ISO 10012, which has a status of a Czech Standard (ČSN EN ISO 10012). It’s focused on roughness measurement. The thesis was written in cooperation with a private company called PLASMAMETAL Ltd. situated in Brno. The company offers coating applications for a variety of materials. Important part of the thesis is a measurement management system improvement manual for PLASMAMETAL Ltd. It’s also dealt with the economical aspect of an investement into a new measurement equipment.
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Produktivní obrábění titanových slitin / Productive Machining of Titanium AlloysČejka, Libor January 2013 (has links)
The aim of the thesis is to analyze the production costs and optimize cutting conditions for high-feed face milling of titanium alloy Ti6Al4V. In the experiment were changed cutting conditions, such as cutting speed vc and feed speed vf. During the experiment were checked cutting forces by dynamometr. Furthermore, surface roughness and tool wear is observed.
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Volba a optimalizace řezných podmínek pro progresivní výrobní technologie vrtání sdruženým nástrojem / Data selection and optimisation of cutting conditions for progressive production technologies of drilling with a step drillBarák, Vít January 2015 (has links)
The thesis contains theoretical analysis of drilling by twist drill focused on the step drill. The review includes description of the drill geometry, calculation of the basic parameters of drilling, including forces and process optimization. Following is manufacturing process and analysis of the monolithic step drill designed for the required hole parameters. The optimal cutting conditions are necessary to find for the correct function of the tool. The load values of the tool are accurately assessed using a piezoelectric dynamometer, thereby obtaining the overall progress of individual loads. The roughness of the workpiece is evaluated by the optical measuring device.
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Vliv povrchových rýh na přechod ke smíšenému mazání / The effect of surface grooves on transition to mixed lubricationZapletal, Tomáš January 2016 (has links)
The purpose of this diploma thesis is to describe the influence of artificially produced surface grooves on transition from full EHL regime to mixed lubrication in point contact using optical interferometry. This article focuses on influences of grooves orientation, length in contact area, elastic properties of contact surfaces and different types of oil defined by pressure-viscosity coefficient. Empirical prediction model of groove influence on film thickness was established based on experimental data. The groove influence was incorporated into lubrication parameter. This modified definition was compared to classic one. It showed that avoiding groove influence in classic definition lead to significant underestimation. Influence of groove on friction coefficient is also studied.
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Studium kvality řezu mezních tlouštěk oxidačního řezání v závislosti na průměru ohniskového spotu při laserovém dělení materiálu / Study cutting quality of flame cutting of limit thicknesses depending on the diameter of the focal spot during laser cutting of materialMaňas, Petr January 2016 (has links)
Experimental work evaluated the dependence of the thickness of the cutting edge, its roughness and assessment of appearance with regard to the defects resulting from the diameter of the focal spot during oxidative cutting Yb:YAG laser. Other variables include the experiment: process parameters such as laser power, cutting speed, oxygen pressure and focus position. Experiment is based on the Taguchi tables. Test samples were cut off from sheet thickness 10, 15 and 20 mm. Representatives of conventional steel were S235JRC+N, S235JR, S235JR+N and steel type RAEX developed for laser and plasma cutting. Samples were evaluated according to the ČSN EN ISO 9013. The evaluation of samples was into classes according to standards of quality. Hardness measurements were performed on the samples thickness 20 mm of convectional steel and steel type RAEX.
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The effect of surface roughness on Nuclear Magnetic Resonance relaxationNordin, Matias, Knight, Rosemary January 2016 (has links)
Most theoretical treatments of Nuclear Magnetic Resonance (NMR) measurements of porous media assume ideal pore geometries for the pores (i.e. slabs, spheres or cylinders) with welldefined
surface-to-volume ratios (S/V). This same assumption is commonly adopted for naturally occurring materials, where the pore geometry can differ substantially from these ideal shapes. In this paper the effect of the roughness of the pore surface on the T2 relaxation spectrum is studied. By homogenization of the problem using an electrostatic approach it is found that the effective surface relaxivity can increase dramatically in the presence of rough surfaces. This leads to a situation where the system responds as a pore with a smooth surface, but with
significantly increased surface relaxivity. As a result the standard approach of assuming an idealized geometry with known
surface to-volume and inverting the T2 relaxation spectrum to a pore size distribution is no longer valid. The effective relaxivity is found to be fairly insensitive to the shape of the roughness but strongly dependent on the width and depth of the surface geometry.
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A study of micro- and surface structures of additive manufactured selective laser melted nickel based superalloysStrand, Emil, Wärnheim, Alexander January 2016 (has links)
This study examined the micro- and surface structures of objects manufactured by selective laser melting (SLM). The results show that the surface roughness in additively manufactured objects is strongly dependent on the geometry of the built part whereas the microstructure is largely unaffected. As additive manufacturing techniques improve, the application range increases and new parameters become the limiting factor in high performance applications. Among the most demanding applications are turbine components in the aerospace and energy industries. These components are subjected to high mechanical, thermal and chemical stresses and alloys customized to endure these environments are required, these are often called superalloys. Even though the alloys themselves meet the requirements, imperfections can arise during manufacturing that weaken the component. Pores and rough surfaces serve as initiation points to cracks and other defects and are therefore important to consider. This study used scanning electron-, optical- and focus variation microscopes to evaluate the microstructures as well as parameters of surface roughness in SLM manufactured nickel based superalloys, Inconel 939 and Hastelloy X. How the orientation of the built part affected the surface and microstructure was also examined. The results show that pores, melt pools and grains where not dependent on build geometry whereas the surface roughness was greatly affected. Both the Rz andRa values of individual measurements were almost doubled between different sides of the built samples. This means that surface roughness definitely is a factor to be considered when using SLM manufacturing.
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Surface Topography and Aesthetics of Recycled Cross-Linked Polyethylene Wire and Cable CoatingsXie, Wa 12 1900 (has links)
Our research focuses on re-using a waste a material, cross-linked polyethylene abbreviated XLPE, which is a widely used coating for wires. XLPE is strong and has excellent thermal properties due to its chemical structure - what leads to the significance of recycling this valuable polymer. Properties of XLPE include good resistance to heat, resistance to chemical corrosion, and high impact strength. A wire is usually composed of a metal core conductor and polymeric coating layers. One creates a new coating, including little pieces of recycled XLPE in the lower layer adjacent to the wire, and virgin XLPE only in the upper layer. Industries are often wasting materials which might be useful. Mostly, some returned or excess products could be recycled to create a new type of product or enable the original use. This method helps cleaning the waste, lowers the costs, and enhances the income of the manufacturing company. With the changing of the thickness of the outer layer, the roughness changes significantly. Moreover, different processing methods result in surfaces that look differently.
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Fatigue Properties of Additively Manufactured Alloy 718Balachandramurthi, Arun Ramanathan January 2018 (has links)
Additive Manufacturing (AM), commonly known as 3D Printing, is a disruptive modern manufacturing process, in which parts are manufactured in a layer-wise fashion. Among the metal AM processes, Powder Bed Fusion (PBF) technology has opened up a design space that was not formerly accessible with conventional manufacturing processes. It is, now, possible to manufacture complex geometries, such as topology-optimized structures, lattice structures and intricate internal channels, with relative ease. PBF is comprised of Electron Beam Melting (EBM) and Selective Laser Melting (SLM) processes. Though AM processes offer several advantages, the suitability of these processes to replace conventional manufacturing processes must be studied in detail; for instance, the capability to produce components of consistent quality. Therefore, understanding the relationship between the AM process together with the post treatment used and the resulting microstructure and its influence on the mechanical properties is crucial, to enable manufacturing of high-performance components. In this regard, for AM built Alloy 718, only a limited amount of work has been performed compared to conventional processes such as casting and forging. The aim of this work, therefore, is to understand how the fatigue properties of EBM and SLM built Alloy 718, subjected to different thermal post-treatments, is affected by the microstructure. In addition, the effect of as-built surface roughness is also studied. Defects can have a detrimental effect on fatigue life. Numerous factors such as the defect type, size, shape, location, distribution and nature determine the effect of defects on properties. Hot Isostatic Pressing (HIP) improves fatigue life as it leads to closure of most defects. Presence of oxides in the defects, however, hinders complete closure by HIP. Machining the as-built surface improves fatiguelife; however, for EBM manufactured material, the extent of improvement is dependent on the amount of material removed. The as-built surface roughness, which has numerous crack initiation sites, leads to lower scatter in fatigue life. In both SLM and EBM manufactured material, fatigue crack propagation is transgranular. Crack propagation is affected by grain size and texture of the material.
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Advanced Methods for the Solution of Journal Bearing Dynamics / Advanced Methods for the Solution of Journal Bearing DynamicsMaršálek, Ondřej January 2015 (has links)
Náplní této disertační práce je popis komplexní a obecně použitelné strategie výpočetního modelování chování kluzných ložisek, pracujících v režimu smíšeného mazání a uvažujících reálné struktury drsných povrchů obou členů kluzných ložisek – ložiskových pánví a ložiskových čepů. V práci jsou uvedeny a detailně popsány způsoby získání charakteristických popisných dat těchto drsných povrchů a její nedílnou součástí je i popis numerických algoritmů, sloužících k následnému zpracování těchto dat. Dále jsou zde rozebrány implementované výpočetní přístupy k modelování kontaktního tlaku. Ovlivnění hydrodynamické mazací vrstvy kluzných ložisek je dáno velikostí a průběhem faktorů toku, jejichž numerické stanovování je zde detailně popsáno. Alternativní stanovení faktorů toku pomocí analytických funkcí je zde pro úplnost rovněž obsaženo. V závěru práce je uveden popis numerického řešiče modelování chování kluzných ložisek spolu s uvedenými výsledky provedených simulací a jejich diskuzí. Ověření jednotlivých výpočetních modelů, popřípadě porovnání výsledků s výsledky získanými alternativním způsobem, je uvedeno v příslušných kapitolách.
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