This thesis is focused on the study of changes in properties of the aqueous suspensions of corundum during ultrafine grinding without and with the addition of grinding activator. Such studies are an important step in  optimizing the grinding process properly, because by measuring physical properties of a particulate substance, it is easy to determine the actual fineness of the ground substance and its quality for further processing. For the measurement of granulometry, zeta potential, rheological behavior and turbidity, corundum suspensions in distilled water were prepared in a 1:5 ratio without the addition of grinding activator and with the addition of triethanolamine (TEA), by using a planetary mill. The suspensions showed pseudoplastic behavior and the zeta potential of all samples ranged between -30 and 30 mV, thus the suspensions were rather unstable. During the grinding, the viscosity and turbidity of the samples increased. TEA was not proved to be a suitable activator for wet milling of corundum because of higher degree of fineness achieved during milling without an activator.

Diploma thesis is focused on the treatment of biofuel prior to combustion and effect of this treatment on the biofuel characteristics. The first part is a review of literature encompassing characteristics of fuel, preparation of samples, methods of analysis of individual characteristics and a presentation of various types of mills. The second part of thesis is experimental. It is an analysis of sample characteristics under various mill settings with regard to the temperature in the mill during grinding.

Since grinding is often the last process of a manufactured part, caution has to be taken in order to ensure the integrity of the surface. The role of grinding induced residual stresses can be important in fatigue or wear resistance. In most cases we cannot evaluate accurately and easily their distribution. On this purpose, many scientists are working on the modeling of grinding and its effects on a many points. The main aim of this work is to analyse of residual stresses influenced by grinding parameters.

he aim of this thesis is possibilities analyse of automatization of finishing operations by producing bodies of plumbing fittings and selection it’s optimal version. The objective is project of workplace for conditions of concrete production plant and verification of return of it’s operating. A part of thesis is design of workplace and design of production machines and komplete technology of prodicing of parts in setting of production plant. Than there is partial verification of profected technology by real testing.

Orientador: Eduardo Carlos Bianchi / Coorientador: Luiz Eduardo de Angelo Sanchez / Banca: Luiz Dare Neto / Banca: Hamilton José de Mello / Banca: Alessandro Roger Rodrigues / Banca: Rodrigo Eduardo Catai / Resumo: Na indústria metal-mecânica, por ser considerado uma etapa final e de acabamento, o processo de retificação contém valor agregado alto ao produto final. Neste processo a utilização de fluidos de corte é um dos fatores responsáveis na obtenção da qualidade final do processo, porém a eles são atribuídos fatores de risco à saúde e ao meio ambiente. Diante do contexto, diversos setores da indústria, pesquisa e educação, são mobilizados a buscar novas alternativas que possam reduzir custos e que sejam menos prejudiciais ao meio ambiente e uma das alternativas já em estudo é a técnica de mínima quantidade de lubrificante (MQL), que é caracterizada pela eficiência do processo em se aplicar uma quantidade menor de fluido de corte, se comparada com o método de lubrirrefrigeração convencional. Porém, na aplicação de MQL é importante que seja observado a pouca eficiência quanto a limpeza da superfície de corte do rebolo, acarretando na obstrução dos poros do rebolo e prejudicando as arestas cortantes. Diante do exposto, o presente trabalho teve como objetivo analisar o comportamento da técnica de MQL associada à limpeza do rebolo, integrada ao sistema de ar a baixa temperatura aplicado à zona de corte, de forma a preservar os parâmetros como: lubrirrefrigeração e limpeza da zona de corte com jato de ar comprimido a baixa temperatura. Neste trabalho foram realizados estudos resultantes da retificação cilíndrica do aço ABNT 4340, e utilizando o rebolo convencional de óxido de alumínio bra... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the metalworking industry, for being the grinding process is considered a final stage and finishing, the grinding process has high added value to the final product, in this process the use of cutting fluids is one of the factors responsible for obtaining the final quality of the process, however they are attributed risk factors to health and the environment. In this context, several sectors of industry, research and education are mobilized to seek new alternatives that can reduce costs and that are less harmful to the environment and one of the alternatives already under study is the technique of minimum quantity lubricant (MQL), which is characterized by the efficiency of the process in applying a smaller amount of cutting fluid as compared to the conventional flood coolant method. However, in the application of the MQL it is important to observe the low efficiency of the cleaning of the cutting surface of the grinding wheel, resulting in clogging of the grinding wheel pores, damaging the sharp edges. Thereupon, the present study addresses the behavior of the MQL technique associated to the cleaning of the grinding wheel, integrated to the cold air system applied to the cutting zone, in order to preserve the parameters such as: flood coolant and cleaning of the cutting zone with air jet compressed at low temperature. In this thesis, studies were carried out resulting from the grinding of ABNT 4340 steel and using the conventional white aluminum oxide grinding wheel under the application of different lubrication and cooling conditions, where the conventional method can be compared to the MQL technique associated to cleaning at cold -10º C and -15º C. The results obtained were characterized by roughness tests, circularity deviation, diametrical wear grinding wheel, metallographic analysis, optical microscopy, microhardness and analysis of the influence of the flood coolant. Both the flood coolant metho / Doutor

Orientador: Eduardo Carlos Bianchi / Banca: Carlos Eiji Hirata Ventura / Banca: Manoel Cleber de Sampaio Alves / Banca: Dayse Iara dos Santos / Banca: Rafael Plana Simões / Resumo: Atualmente, vários setores industriais têm buscado um desenvolvimento sustentável para os seus projetos. Dentre estes setores está a usinagem por abrasão, devido ao enrijecimento das leis ambientais e em virtude da necessidade de diminuição dos custos envolvidos na produção. A partir desse contexto, o presente trabalho buscou explorar as potencialidades da técnica de lubri-refrigeração de Mínima Quantidade de Lubrificação (MQL) em função da diluição de três diferentes fluidos de corte comparada à técnica lubri-refrigeração convencional no processo de retificação cilíndrica do aço ABNT 4340, temperado e revenido, com o rebolo de nitreto cúbico de boro (CBN). A influência das proporções da diluição dos fluidos utilizados na técnica de lubri-refrigeração MQL sem limpeza e com limpeza da superfície do rebolo, por um jato de ar comprimido, respectivamente, foram estudados através das análises de: rugosidade, desvio de circularidade, desgaste diametral do rebolo ou relação G, microdureza, potência, emissão acústica e vibração. Os resultados demonstraram que o aumento da proporção de água utilizada na diluição dos fluidos testados promoveu uma diminuição dos valores da rugosidade, do desvio de circularidade, do desgaste do rebolo, da emissão acústica e da vibração. No entanto, essa mesma proporção de diluição dos fluidos contribuiu para que potência consumida durante o processo sofresse aumento. Fazendo uma avaliação global dos dados conclui-se que o processo de retificação do aço A... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Currently, several industrial sectors have been looking for a sustainable development to your projects. The process by machining abrasion needs to be optimized due to environmental laws and to the production costs. In this study, the potentialities of the Minimum Quantity Lubrication (MQL) technique using dilution of three different cutting fluids were compared to the conventional lubrication-cooling technique. The grinding process was analyzed using a cylindrical steel grinding process ABNT 4340, with cubic boron nitride (CBN) wheel. The influence of the dilution proportions of the fluids used in the MQL technique without cleaning and with the cleaning of the wheel surface by a jet of compressed air respectively. The study was realized following output variables: roughness, roundness errors, diametrical wheel wear or G ratio, microhardness, power, acoustic emission, and vibration. The results showed that the increase in the proportion of water used in the dilution of the tested fluids promoted a decrease in the values of roughness, roundness errors, diametrical wheel wear, acoustic emission, and vibration. However, this same proportion of dilution of the fluids contributed to the increase in power consumed during the process. Making an overall assessment of the data concludes that the grinding process of ABNT 4340 steel through the MQL technique with wheel surface cleaning and application of diluted fluid in the 1:10 ratio proved to be efficient in obtaining parts with a sur... (Complete abstract click electronic access below) / Doutor

OBJECTIVES: To evaluate accelerated and real time aging effect on microstructure and mechanical properties of different types of zirconia’s with various surface treatments. METHODS: In this in-vitro study 830 discs were prepared from four Y-TZP based materials. These materials were TZ-3YSB-E, ZPex®, ZPex® Smile (Tosoh Corporation, Japan), and Cercon®xt extra translucent zirconia (Dentsply-Sirona). Final dimensions of each specimen disc were about 15 mm in diameter and 1.5 mm thick. An accelerated aging process for 5, 24, and 168 hours of steam aging at 134°C under a pressure of 0.2 MPa was applied to the specimens. Real time aging was performed for one year in normal saline solution at 37°C in an incubator. Sandblasting was performed using a PrepStar® system with Al2O3 50μm particle size at pressure of 60 psi, rate 4.2 gram/minute. Grinding with a Buehler AutoMet 250 was performed using a 240 μm diamond disc with a 0.0034 kg/mm2 load and speed of 120 rpm for two minutes. Bruker D8 advance diffractometer was used for the acquisition of X-ray diffraction (XRD) spectrum. Biaxial flexural strength was determined using a ball-on-three-balls configuration in a universal testing machine. Scanning Electron Microscopy (SEM) was used to examine the sample's surface topography. RESULTS: The results of this study show that the zirconia materials with smaller grain size have higher flexural strength. Sandblasting and grinding treatment increases the tensile flexural strength of TZ-3YSB-E and ZPex® compared to the controlled group of the same material. XRD analysis shows that TZ-3YSB-E at room temperature does not have any monoclinic phase before surface treatment and it increased after aging, sandblasting and grinding. Cercon®xt has the highest amount of cubic phase and it increases with surface treatment. CONCLUSION: Sandblasting surface treatment should not be applied to all types of zirconia and it has to be material specific. Within the scope of this study, accelerated aging process did not affect the grain size of all materials control groups. The smaller grain size of zirconia is correlated to higher flexural strength of the material. The smaller amount of cubic phase present is correlated to higher biaxial flexural strength.

High-speed plunge-cut centreless grinding opens up enormous potential for the manufacturing of difficult-to-machine materials and to improve the surface quality while reducing the grinding forces. For this investigation, a new grinding wheel base body of carbon fibre-reinforced plastic (CFRP) was developed to achieve grinding wheel speeds up to 150 m/s in plunge-cut centreless grinding of hardened shafts. For evaluation of the performance characteristics, the grinding forces and the surface quality of different grinding tools were detected. These experiments were conducted using a newly developed measuring system to analyse the grinding forces in the workrest blade. The experimental results are described and discussed in this article.

On the Island of Gotland, there is a phenomenon called grinding grooves, Sw. slipskåror. They occur in bedrock and boulders. About 3600 are known on the island today and having a length of less than half a meter to over one meter. Their purpose was unknown to the scientific community as well as their age. The directions of some 1250 Gotlandic grinding grooves, measured by the author shows there is a correlation to astronomical orientations. An archaeological excavation carried out by the author at a stone with grinding grooves gave some crucial results. The grinding groove phenomenon occurs in some other places in the world as well. In South-West of Sweden, there are quite many in a few places. They are, however shorter and have another appearance because they are more curvature than the Gotlandic ones. Their purpose and age are unknown as well. In France, there are many places with grinding grooves, Fr. polissoirs. Their appearance is more similar to the Gotlandic ones than those in the Swedish mainland. They are supposed to be Neolithic.  In Africa and Australia, there are places with different kinds of carvings in stones. Some resemble those mentioned above, more or less. The difference between grinding grooves and other phenomena is floating.  They are sometimes associated with the circular indentations called cup marks. There are different explanations, and some are supposed to be marks from creating stone tools, while the cult is the explanation to others.

Thesis solves the problem of influence of variable process conditions during grinding on surface texture parameters, provides precision of measurement methods, assessed by laser interferometry measurement methods and piezoelectric measurement of vibration of technological equipment and processes using statistical methods the correlation between the amplitude of oscillation and on surface texture parameters. Further it provides the prediction of the impact of input parameters to the output parameters of the technological process for a long-term perspective.