In today’s society, dental implants are a growing solution for dental care. However, most dental components are very expensive when imported, and are purchased at premium costs solely from a few international companies. It is estimated that the current market price of dental implants is as much as one thousand times the material cost. To be cost effective in a growing competitive market, a local company is looking into producing their own components, and requires knowledge of manufacturing and quality assurance or expertise in order to validate the effectiveness of their fabricated components. These fabricated components need to be tested against currently in use market components in order to assure that prototype components are not inferior to the current market supply. The present study focuses on the analysis of the fabrication process of dental implants, specifically the abutments and screws. The objective is to compare material properties of prototype and market components to determine if the prototype components have adequate quality. Furthermore, simulated models are developed for predicting material property changes due to the manufacturing process. The material properties are determined through hardness testing and microstructure analysis. Visual inspection is then used to investigate and characterize the components. The simulations use different machining parameters, such as the feed rate and the cutting speed to determine residual stress patterns. Dental implant abutments and screws were successfully tested and compared. The prototypes show a good hardness and microstructure properties similar to market components, indicating a high level of prototype quality. The simulated models were successfully created and provided an adequate level of customization to be usable in place of future mechanical testing and showed results that complimented experimental findings. The standard cutting speed of 2000 rpm (100%) in the prototypes produced the optimal hardness and surface roughness. Prototypes were found to have an acceptable level of both hardness and surface finish for the investigated 50%, 100% and 150% of the standard 2000 rpm feed rate.

Manufacturing by mechanical machining has historically benefited from the use of cutting fluid. Cutting fluids help to reduce temperature, friction, flush away chips, and hence prolong tool life and improve machining performance. However, uncontrolled use of cutting fluid raises concern in respect of cost and environmental burden. For these reasons, dry machining is used in conjunction with high speed machining to reduce cycle times and simultaneously deliver a greener process. However, for some workpiece materials full implementation of dry machining is not economically viable due to the absence of the essential cooling and lubricating functions delivered by cutting fluids. The most feasible bridging technology is minimum quantity lubrication (MQL) where a very small flow rate of coolant/lubricant is delivered to the cutting zones. In terms of machinability, the application of MQL is promising. However, most studies conducted on MQL focused on the feasibility of MQL application and show-casing the technical benefits. No studies had been identified in literature systematically investigating the relationship between cutting conditions and MQL with the goal of optimising the process. Moreover, the presumed environmental benefits of MQL have not been systematically assessed because Life Cycle Analysis (LCA) derived evaluation models do not explicitly model the impact of machining conditions such as feedrates, cutting velocities and depth of cut.The motivation for this PhD work was to select the optimum machining process variables for maximising effectiveness of MQL, to explore process improvements and to assess the environmental credentials of the process in relation to other forms of cutting environments. In this work, high speed, end milling tests on tool steel were undertaken and 1) Taguchi methods were used to optimise the process, 2) the sensitivity of tool wear to nozzle position was evaluated and 3) the environmental burden of dry, MQL and flood coolants were evaluated based on direct energy needs and process outputs. A fluid soaking device was used to assess the amount of fluid collected or presumed to be delivered to the cutting zone for different nozzle orientations.The Taguchi process optimisation suggested that in HSM the size effect, brought about by a low chip thickness, should be considered in the search for an optimum process window for HSM. A significant and novel finding of this PhD was the dominance of MQL nozzle positioning. The study clearly showed that when machining hardened steel at a high cutting speed and RPM the tool life could be significantly increased by 50% by adjusting the position of the nozzle toward the rake face in relation to the end-milled face. The work opens up new science and provides recommendations as to where to align the nozzle when end milling tool steel at high cutting speeds. The fluid trapping and the blade-wiping angle are key parameters that influenced the effective delivery of MQL when high spindle revolutions per minute are used. These results from the fluid soaking device were found to correlate strongly with observed machining performance evaluations.In terms of modelling, the PhD developed an improved and more generic direct energy model that can be used to determine the environmental burden for direct electrical energy requirements and the energy embodied in other process material outputs. This model addresses the system boundary and activity that within the control of the manufacturing plant. The model was used to evaluate the environmental performance of dry, flood and MQL fluids. The impact of these results and models in optimising environmental performance was also illustrated.The work in this PhD is important to industry in that it contributes to the optimisation of MQL and gives an assessment of the environmental impact. The PhD developed new and significantly important machining science in the positioning of nozzles in MQL machining at higher speeds.

M.Ing. / Grade 4 titanium is a commercially pure grade titanium alloy extensively used in various industries including the chemical industry and more recently in the biomedical industry. Grade 4 has found a niche as a biomedical material for production of components such as orthopaedic and dental implants. Its physical properties such as high corrosion resistance, low thermal conductivity and high strength make it suitable for these applications. These properties also make it hard-to-machine similar to the other grades of titanium alloys and other metals such as nickel based alloys. During machining of titanium, elevated temperatures are generated at the tool-workpiece interface due to its low thermal conductivity. Its high strength is also maintained at these high temperatures. These tend to impair the cutting tool affecting its machinability. Various investigations on other grades of titanium and other hard-to-machine materials have shown that machining at high cutting speeds may improve certain aspects of their machinability. High speed machining (HSM) is used to improve productivity in the machining process and to therefore lower manufacturing costs. HSM may, however, change the surface integrity of the machined material. Surface integrity refers to the properties of the surface and sub-surface of a machined component which may be quite different from the substrate. The properties of the surface and sub-surface of a component may have a marked effect on the functional behaviour of a machined component. Fatigue life and wear are examples of properties that may be significantly influenced by a change in the surface integrity. Surface integrity may include the topography, the metallurgy and various other mechanical properties. It is evaluated by examination of surface integrity indicators. In this investigation the three main surface integrity indicators are examined. These are surface roughness, sub-surface hardness and residual stress. White layer thickness and chip morphology were also observed as results of the machining process used. The effect of HSM on the surface integrity of grade 4 is largely unknown. This investigation therefore aims to address this limitation by conducting an experimental investigation on the effect of HSM on selected surface integrity indicators for grade 4. Two forged bars of grade 4 alloy were machined using a CNC lathe at two depths of cut, 0.2mm and 1mm. Each bar was machined at varying cutting speeds ranging from 70m/min to 290m/min at intervals of approximately 20m/min. Machined samples were prepared from these cutting speeds and depths of cut. The three surface integrity indicators were then evaluated with respect to the cutting speed and depth of cut (DoC). iv Results show that a combination of intermediate cutting speeds and low DoC may have desirable effects on the surface integrity of grade 4. Highest compressive stresses were obtained when machining with these conditions. High compressive stresses are favourable in cases where the fatigue life of a material is an important factor in the functionality of a component. Subsurface hardening was noticed at 0.2mm DoC, with no subsurface softening at all cutting speeds. Surface hardness higher than the bulk hardness tends to improve the wear resistance of the machined material. Though surface roughness values for all depths of cut were below the standard fine finish of 1.6μm, roughness values of samples machined at 0.2mm DoC continued to decrease with increase in cutting speed. Low surface roughness values may also influence the improvement of fatigue life of the machined components. These machining conditions, (intermediate cutting speeds and low DoC), seem to have promoted mechanically dominated deformation during machining rather than thermal dominated deformation. Thermal dominated deformation was prominent on titanium machined at DoC of 1mm.

M.Eng. (Mechanical Engineering) / High speed machining (HSM) has the potential to greatly increase productivity and to lower manufacturing costs if workpiece surface integrity can be controlled. The surface fmish of a biomaterial is vitally important for proper implant functioning, and is the focus of this study. Grade 4 titanium was turned on a lathe with cutting speeds increasing from the conventional to the high speed range. The surface finish was assessed using profilometry, atomic force microscopy, and contact angle measurement. The ability of the material to bond directly with bone was predicted by cell adhesion studies. Results indicate that there is a general relationship between cutting speed, surface roughness, contact angle, and cell adhesion. Turning grade 4 titanium at cutting speeds between 150m/min and 200m/min may provide an optimal surface for osseointegration.

Orientador: Amauri Hassui / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-26T13:19:17Z (GMT). No. of bitstreams: 1 Menezes_LucianodeJesus_M.pdf: 3153404 bytes, checksum: 2d45745d89221fa761d7b0111aaf819a (MD5) Previous issue date: 2014 / Resumo: A evolução dos sistemas CAD/CAM, das máquinas-ferramenta CNC e das geometrias e materiais das ferramentas de corte tem tornado possível desenvolver processos de fabricação de moldes e matrizes mais eficazes. Normalmente, a quantidade de horas necessárias para a usinagem dos componentes dessas ferramentas é elevada e, mesmo assim, muitos dos perfis complexos não são possíveis de serem usinados por completo em centro de usinagem 3 eixos, necessitando a utilização de outras máquinas e processos, como a eletro-erosão (EDM), retificadoras e polimento manual. A utilização do fresamento com máquinas de usinagem 5 eixos tem sido um dos caminhos para a usinagem dos componentes complexos de moldes e matrizes, de modo a minimizar o uso de máquinas e processos adicionais. Com a finalidade de contribuir para melhorar a eficiência da fabricação de moldes e matrizes, este trabalho tem como objetivo estudar as condições dimensionais e as forças geradas no fresamento do Aço AISI D6 endurecido a 58HRC, usinado em um centro de usinagem 5 eixos com fresa de topo esférica. A condição dimensional estudada está relacionada com o perfil geométrico do corpo de prova, composto por raio e superfície plana. O estudo foi realizado utilizando 10 estratégias de usinagem, variando-se o ponto de contato da ferramenta com o corpo de prova, o sentido de usinagem e a velocidade de corte. As análises práticas realizadas mostraram que existe relação entre a tolerância geométrica, o desgaste da ferramenta e as estratégias de corte adotadas. Além disso, as condições, máquinas e equipamentos utilizados nos ensaios de usinagens descendentes 3 eixos obtiveram melhores resultados de tempo de vida da ferramenta e condição dimensional do corpo de prova / Abstract: The development of CAD / CAM systems, CNC machine tools and materials and geometries of cutting tools has become possible to develop more efficient manufacturing processes of molds and dies. Usually the amount of hours required for machining of the components of these tools is high. Also, many of the complex profiles are not possible to be completely machined in 3-axis machine center, requiring the use of other machines and processes, such as electro-erosion (EDM), grinding and hand polishing. The use of milling machines with 5-axis machining has been one of the paths for machining complex components from molds and dies, so as to minimize the use of additional machines and processes. In order to contribute to improve the efficiency of manufacturing molds and dies, this work aims to study the dimensional requirements and the forces generated when milling Steel AISI D6 hardened to 58HRC, machined in a machining center with 5-axis milling spherical top. The dimensional condition studied is related to the geometric profile of the specimen, consisting of ray and flat surface. The study was conducted using 10 machining strategies, varying the tool point of contact with the specimen, the machining direction and the cutting speed. The practical analyzes showed that there is a relationship between the geometric tolerance, tool wear and cutting strategies adopted. In addition, the conditions, machinery and equipment used in the machining tests descendants 3 axes obtained better lifetime results tool and dimensional condition of the specimen / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Precisão dimensional e qualidade de superfície usinada são fundamentais em componentes de aplicações mecânicas. Dentre as variáveis que exercem influência sobre estes fatores, está a grande quantidade de calor gerado na usinagem, que deve ser reduzida, minimizando seus efeitos na ferramenta e na estrutura superficial e sub-superficial da peça. Reduzir este calor e seus efeitos é uma das funções da lubri-refrigeração, porém, intensificamse as pesquisas com o objetivo de restringir ao máximo o uso destes fluídos. Neste trabalho, analisou-se a eficiência da lubri-refrigeração na qualidade da superfície usinada, no desvio dimensional e na variação microestrutural de amostras do aço AISI 4140 com diferentes microestruturas, usinado pelo processo de torneamento longitudinal. Observou-se que a lubri-refrigeração não teve efeito considerável sobre a qualidade da superfície usinada, não apresentando uma melhora significativa na rugosidade. Na questão dimensional observou-se que, em mais de 60% dos ensaios realizados, os resultados com e sem a presença da lubri-refrigeração mantiveram-se dentro da faixa de tolerância préespecificada, e na avaliação microestrutural, avaliando a deformação plástica, observou-se que houve uma queda na dureza da borda do material, em comparação com regiões mais próximas do centro do corpo-de-prova. / Dimensional deviation and surface quality are fundamental components for mechanical applications. The variables that influence these factors, the quantity of heat generated must be reduced in order to minimize their effects on tool and on the superficial and sub-superficial structure of the piece. Reducing this heat and its effects is one of the cooling functions; however, the researches trying to restrict the use of those fluids. In this work, the cooling efficiency was analyzed on the surface quality, dimensional deviation and microstructural variation of AISI 4140 steel samples machined with different microstructure by longitudinal turning process. As a result, it was found that the cooling is not a significant effect on surface quality, not improving the roughness. In regard to dimensional, it was noticed in more than 60% of tests that the results with and without the presence of cooling kept between the pre-specified tolerance ranges. In the microstructural analysis, analyzing the plastic deformation, it as noticed that the hardness decrease in the edge of the sample, comparing with the center.

Orientador: Anselmo Eduardo Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-28T12:31:16Z (GMT). No. of bitstreams: 1 Loureiro_Daniel_M.pdf: 3345826 bytes, checksum: a140e145cbae9ae1a5f3f14eaee94c0f (MD5) Previous issue date: 2015 / Resumo: As ligas de níquel são utilizadas em diversos setores industriais sempre que há necessidade de se associar elevada resistência mecânica com resistência à corrosão, ao desgaste e à oxidação. No entanto, as ligas de níquel apresentam baixa usinabilidade, implicando em processos relativamente ineficientes nos quais o desgaste da ferramenta e a integridade superficial são os principais fatores limitantes. A baixa usinabilidade destas ligas está relacionada com as suas características inerentes, tais como: alta dureza e resistência mecânica a quente, altas tensões de cisalhamento durante o processo de corte, alta taxa de encruamento, presença de carbonetos abrasivos na matriz, baixa condutividade térmica e soldagem da peça e da aresta de corte. Dentre as ligas de níquel, uma que apresenta propriedades desejadas para a indústria de exploração de petróleo é a liga 625. O objetivo do presente trabalho é a verificação da integridade da superfície usinada da liga 625, pela caracterização através da rugosidade, microestrutura, microdureza Vickers da superfície e da subsuperfície e da tensão residual de oito diferentes superfícies torneadas com diferentes geometrias da ferramenta (positiva e negativa) e diferentes condições de usinagem. Neste trabalho foram avaliados os danos que o torneamento em condições de acabamento proporciona à superfície usinada e que podem resultar em variação da resistência à corrosão e à fadiga. Dentre os principais resultados destaca-se aquele que aponta que as superfícies torneadas com geometria positiva da ferramenta produziram tensões compressivas na superfície, enquanto aquelas torneadas com ferramentas negativas produziram tensões trativas na superfície / Abstract: The nickel alloys are used in many industrial sectors where there is a need to associate high mechanical strength with resistance to corrosion, wear and oxidation. However, nickel alloys have poor machinability, resulting in relatively inefficient process wherein tool wear and surface integrity are the limiting primary factors. The low machinability of these alloys is related to their inherent characteristics, such as hot hardness and mechanical resistance, high shear rates during the cutting process, high work hardening rate, presence of abrasive carbides in the matrix, low thermal conductivity and welding the workpiece and cutting edge. Among the nickel alloys, one that has desired properties to the oil exploration industry is the alloy 625. The aim of this work is the check of the surface integrity through the characterization by roughness, microstructure, microhardness of the surface and sub- surface and residual stress, of eight turned different surfaces with different geometries tool (positive and negative) and machining conditions. This study evaluated the damage that finish conditions provides to the machined surface and witch can result in variations of resistance to corrosion and fatigue. Among the main results stands out the one who points out that turned surfaces with positive tool geometry produced compressive residual stresses on the surface, while those with negative turned tools produced tensile residual stresses on the surface / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Machine tool coolant concentration and pH data.

This thesis deals with redesigning of the current technological manufacturing process and subsequent production of a centrifugal impeller of a small tubojet engine. Thesis is divided into three main parts. First part deals with the theoretical background of the turbojet engines and the centrifugal impeller. Next part is focused on the proposed manufacturing technology of the centrifugal impeller using machining. Final part of the thesis deals with evaluation of the achieved goals.

Úvod Vzhledemke zvyšování počtu objednávek leteckých součástek se společnost ArianeGroup rozhodla zintenzívnit svoji činnost, aby uspokojila tuto poptávku. Objem jejích součástí vyrobených za jeden rok se výrazně zvětšil, a tedy výrobní servis musí být funkčně optimalizován. Cílem uvedené optimalizace je snížit počet stop machines. Existuje nepřeberné množství řešení, která se potýkají s problémem, jak snížit počet stop machines, nicméně je velmi obtížné implementovat tato řešení přímo na stroji. Situaci určitě nelze řešit zastavením výroby a následnou implementací nějakých technických řešení. Avšak je naopak možné implementovat technická řešení už v samotném průběhu kvalifikační fáze. Kvalifikační fáze probíhá tehdy, když je součást poprvé na stroji. Tři části byly kvalifikovány a nějaká technická řešení byla aplikována právě v průběhu těchto kvalifikací. Bezpečnost procesu Prvním aspektem, na který bych se rád zaměřil, je bezpečnost samotného procesu. Nesmí dojít k vysouvání součásti z upínacích čelistí. Právě proto je požadován výpočet upínacího tlaku disku D. Druhým aspektem práce je nedeformování součásti. Díky vysokému upínacímu tlaku je přítomna geometrická deformace. Z tohoto důvodu bylo důležité provést výpočty upínacích tlaků pro disky D a B. Cílem je zjištění, zda je možné snížit upínací tlak a zároveň respektovat podmínku, že se součást nebude vysouvat z čelistí. Za třetí je důležité zaručit bezpečnost procesu. Někdy se stává, že obslužní pracovníci zapomenou odstranit příruby. Z tohoto důvodu sem byl umístěn automtický detektor, který upozorní na to, že externí příruby nebyly odstraněny. Automatická sekce pomáhá vyvarování se kolizím. Jak je možno vidět na obr. 1, sonda detekuje vnitřní příruby. Objeví se zpráva, dveře se otevřou a obslužný pracovník je upozorněn. Odolnost procesu . Robustní process je process s nízkým počtem rozbíjení nástrojových destiček. Existuje technické řešení. Skládá se z iplementace a monitorování opotřebení nástroje. To vše je možné díky sondě a aBLUM laseru. Během vyhodnocení disku D, soustružnické nástroje jsou kontrolovány pomocí sondy a nástroje frézovací pomocí BLUM laseru. Výkonnost procesu Inovativním přístupem ke zlepšení řezných podmínek je integrace vysokého tlaku. Ten byl použit pro některé ze součástí. Dalším řešením je integrování tool sisters do procesu. Během kvalifikace disku D, byly přidány tools sisters. Navíc, byla provedena studie pro zvládnutí nástroje a jeho zablokování poté, co byl použit. Nové technologie destiček byly využity pro zlepšení řezných podmínek a snížení času. Automatizace operací ve strojírenské výrobě Zásadním důvodem pro stop machines je prostorová kontrola pomocí obslužných pracovníků. Technicky je totiž možné nahradit tyto činnosti automatickými kontrolami, přičemž zmíněné automatické kontroly se provádí pomocí automatických sond. Proces může být zkreslený, pokud je měření nepřesné. Byly provedeny pokusy pro kalibraci řešení. Aktualní provedení kalibrací nebylo dostačují