H13 tool steel is widely used in the mold and die industry. Due to tighter geometric tolerances and higher quality expectations, the use of hard machining has increased over the years. Hard machining refers to the machining of materials in their hardened state. The challenges with hard machining are rapid tool wear and maintaining a high surface integrity of the machined surface. Surface integrity is measured in terms of surface roughness, residual stresses, presence of surface and subsurface cracks, and the quality of the developed microstructure. In order to minimize wear and improve product quality, researchers are working on the development of different tool coatings. Some of the recent tool coatings function by adapting to their environment using heat to form thin layers of oxides, referred to as ―tribo-films‖, on the surface of the tool. If engineered properly, these tribofilms can prolong tool life and improve the surface integrity of a hard machined surface. A titanium based nano multi-layered coating (TiAlCrSiYN/TiAlCrN) has been developed by researchers at the MMRI. The tribological performance of two different coatings TiAlCrSiYN/TiAlCrN and TiAlCrN were tested in a hard machining metal cutting process. The impact of these coatings on tool wear, Cutting process (Chips) and Surface Integrity (Quality of machined surface) was assessed. This research involves characterizing the coating to understand how the formation of different oxide films (tribofilms) effect tool wear and surface integrity. The generation of these tribofilms is sensitive to coating composition and cutting condition (temperature/pressure). Next, an in-depth characterization of the chips produced during machining was carried out as part of studying the effect of different tribological conditions between the tool and workpiece. The chip's hardness, oxidation, chip formation mechanism and topography as the chip slid against the cutting tool surface was studied. Also, the Surface integrity of the machined part was investigated, considering its microstructure, residual stresses and surface roughness. Lastly, tests were performed in an attempt to accelerate the generation of beneficial tribofilms. Results indicate significant improvement in wear life and surface integrity of the machined surface due to the generation of tribo-films in this machining application. / Thesis / Master of Applied Science (MASc)

Inconel 617 is a nickel-based superalloy whose properties include corrosion and oxidation resistance in high temperature environments. Due to their material properties, Inconel alloys are commonly used in aerospace applications where resistance to high pressure and temperature is required. These properties also cause the material to be hard to machine due to high temperatures in the cutting zone and its tendency to work harden. This paper focuses on improving the surface integrity and tool life for turning of Inconel 617 for use in next-generation nuclear applications. Various machining parameters are tested to improve the finish and tool life such as the feed rate, cutting speed, and depth of cut. While the machining of popular Inconel grades, such as Inconel 718, have been highly studied and understood, Inconel 617 lacks the knowledge base and research to define how the alloy behaves in machining and how it compares to other grades. Tests on tool coatings confirmed that commercially available coatings are durable enough to withstand the machining of this superalloy in finish turning and determined that AlTiN coatings provide the longest tool life. The investigations performed uncovered the relationship between cutting parameters and their influence on the surface integrity and tool life. MQL deposition was tested and found to be comparable and at times better than conventional flood coolant and may be considered a replacement for coolant after more improvement. This work details the knowledge and experimental procedure used to understand the machining of this superalloy. / Thesis / Master of Applied Science (MASc) / The purpose of this research is to develop an understanding of the machining of Inconel 617 for next-generation nuclear reactors. Canada’s plan to phase out coal-fired plants and deploy new nuclear reactors is contingent on being able to manufacture the necessary components. Inconel 617 is slated to be used in these high temperature, corrosive environments due to its high strength in elevated temperatures and its resistance to corrosion. However, since the material is a recent addition to the list of compatible materials, not much research has been performed on the manufacturing of this superalloy. Factors like cutting speed, coolant, and tooling were investigated and understood with the aim of improving the cost and time associated with manufacturing these nuclear grade components.

No description available.

No description available.

No description available.

During machining, the cutting tool wears out and affects the machined surface quality and overall production cost. The prediction of tool wear and analysis of cutting mechanics has significant importance for process optimization and cutting-edge design. In this present study, an efficient FE simulation approach (Arbitrary Eulerian-Lagrangian) on the Abaqus/Explicit platform has been developed to improve the predictability of flank wear and to select the appropriate tool edge geometry in the orthogonal turning operation. The FE model was calibrated by comparing the simulation and experimental force values. A new approach was applied to capture the worn tool geometry based on the frictional stress value acting on the cutting tool. The effect of wear geometry on the cutting zone was investigated with respect to temperature, normal stress, sliding velocity, and plastic deformation. The experimental tool wear pattern and characteristics for the differently prepared edges were studied and compared to the thermo-mechanical value retrieved from the FE model. Tool wear for differently prepared edges was calculated using Usui’s wear rate equation, which was calibrated using a hybrid calibration method. The efficiency of the calibration method was investigated at different cutting speeds and feed rates. The performance of pre-coating edge preparation was evaluated in both experimental and numerical studies. / Thesis / Master of Applied Science (MASc)

This thesis is focused on gaining a better knowledge of how to design and test Phillips screwdriver bits. Wear is the primary concern in applications where the bit is used in a power driver. Such applications include drywalling, decking and other construction and home projects. To pursue an optimal design, designers must have an understanding how the bit geometry changes with wear. To make use of the geometrical data, the designer must also have an understanding of the fundamentals of the bit/screw surface contact and its effect on force distribution. This thesis focuses on three areas. First, understanding how the tool and bit are used, and what factors contribute to bit wear. With this understanding, a test rig has been designed to emulate typical users and, in doing so, produce the factors that cause wear. Second, there must be a means to analyze geometric changes in the bit as it wears. A method for doing this was developed and demonstrated for a Phillips bit, but the process can be applied to other bits. Finally, the fundamentals of surface contact must be understood in order to apply the geometrical information obtained to improved bit design. / Master of Science

The cutting tool inserts are used in different machining processes and are most often made out of cemented carbide and have different geometries depending on application. During the machining process, the insert is subjected to elevated temperatures and high pressure which cause the insert to be worn out. Depending on the cutting conditions different wear mechanism and wear types appear on the insert. One of the most common wear types are flank wear but according to experts there is a lack of publication in this area and there are not sufficient information about how flank wear affects the thermo-mechanical loads that act on the insert. The present project was performed together with AB Sandvik Coromant with the aim to develop a fundamental understanding of loads on worn cemented carbide inserts during metal cutting. An additional aim is to investigate to which degree of detail the thermo-mechanical loads on the flank wear land (VB) can be modeled with regards to e.g. the angle between the wear land and the cutting direction. This was executed by modeling a worn insert in CAD and then importing the model to the software AdvantEdge, to simulate the cutting process. The results from the simulations are presented with TecPlot as figures showing the temperature and pressure distributions on the insert as well as plots generated in MATLAB showing the contact pressure. While analysing the results it was partly found that varying the VB affected the distribution of load and stresses. It was also found that the temperature decreased as the angle of the flank wear decreased. The highest temperatures were present was along the part of the rake face closest to the cutting edge, as well as at the bottom of the VB. Possible future outlooks in this area of work is to investigate how to get a more refined mesh on the workpiece, in order to optimize the cutting process and its results.

Made available in DSpace on 2016-12-08T17:19:21Z (GMT). No. of bitstreams: 1 Elco da Silva.pdf: 3740304 bytes, checksum: b363ccd0dc2bdce0fadf7011311bf319 (MD5) Previous issue date: 2014-01-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / On the present days much effort has been given in the improvement of the strength of materials used in the automotive industry. And it is a great challenge to machine these materials due to the high machining time cycles and tools. This motivated several studies mainly for the Compacted Graphite Iron. The objective of this work is to evaluate the machinability of compacted graphite iron class 350 compared to compacted graphite iron class 400 and 450 and the grey iron class 300. The CGI 350 is object of study to be applied in cylinder heads. In the machinability of a cylinder head, one of the most important process is milling, which was chosen to evaluate these materials. To perform the tests two types of tools (inserts) were used: carbide and CBN. There were used two cutting speeds (Vc) for the carbide tools and one for the CBN. The machinability criteria used were: maximum tool wear (VBmax), edge wear, the power consumed by the machine tool and the roughness of the surface. The result show that, with the increase of the cutting speed, there is higher tool wear. Also the compacted graphite iron presented lower machinability compared to the grey iron. It is also noted that, with higher percentage of ferrite in compacted graphite iron, there is a higher tool wear. The compacted graphite iron class 450 presented the higher power consumption during milling. This alloy has the greatest strength and hardness among the materials studied. Regarding the surface finish of the materials, the compacted graphite iron class 450 presented the best results evaluated in the beginning and at the end of tool lives for both cutting speeds. / Atualmente trabalha-se muito na melhoria da resistência mecânica dos materiais utilizados na confecção de peças automotivas. E está sendo um desafio para a usinagem realizar seu processo nesses materiais, devido ao alto tempo de usinagem e alto custo com ferramentas de corte. Esta foi uma dificuldade inicial no desenvolvimento de blocos de motor em ferro fundido vermicular, e que motivou uma série de estudos. O objetivo deste trabalho é avaliar a usinabilidade do ferro fundido vermicular classe 350 comparando com o vermicular classe 400 e 450 e o cinzento classe 300. O ferro fundido vermicular classe 350 está sendo estudado para aplicação em cabeçotes de motores. Na usinagem de um cabeçote de motor o processo de fresamento é um dos principais aplicados a esta peça, foi escolhido este processo para realizar a avaliação da usinabilidade nestes materiais. Para a realização dos testes foram utilizados dois tipos de insertos para a ferramenta (fresa), o inserto de metal duro (MD) e o inserto de nitreto cúbico de Boro (CBN). Adotaram-se duas condições de cortes diferentes para o inserto de MD, com o intuito de avaliar o comportamento da usinabilidade com o aumento da velocidade de corte (Vc) e uma condição de corte para o inserto de CBN. Os testes de usinabilidade foram realizados de três formas: avaliação do desgaste de flanco máximo (VBmáx.) do inserto, a potência consumida de corte pelos eixos da máquina durante a usinagem e a avaliação do acabamento da superfície usinada (rugosidade) do corpo de prova. Os resultados mostram que com o aumento da velocidade de corte para ambos os materiais em estudo, há um aumento do desgaste da ferramenta, e que as ligas em ferro fundido vermicular foram as que apresentaram pior usinabilidade quando comparado com o ferro fundido cinzento. Observa-se também que com o aumento de ferrita na matriz das ligas em vermicular ocorreu um maior desgaste da ferramenta. O ferro fundido vermicular classe 450 foi o que causou a maior potência consumida de corte durante a usinagem, sendo esta liga a que possui o maior limite de resistência e a maior dureza entre os materiais estudados. Com relação ao acabamento da superfície usinada, o ferro fundido vermicular classe 450 foi também o que obteve o melhor resultado, tanto na avaliação de início de vida do inserto quanto no fim de vida para ambos os ensaios realizados.

Made available in DSpace on 2016-12-08T17:19:36Z (GMT). No. of bitstreams: 1 Pre-textuais.pdf: 73538 bytes, checksum: 312651a50c92e3fa74c571281d3cdc0e (MD5) Previous issue date: 2010-06-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / During the last years the Compacted Graphite Iron CGI has acquired a growing placein the automobilist industry. It is used to manufacture several automotive parts, such as disk brakes, exhaust manifolds and, mainly, engine cylinder heads and blocks. Its higher strength, compared to grey cast iron, makes possible the manufacturing of cylinder blocks with higher pressure in the combustion chamber, therefore, more efficient and less pollutant. Lighter engines can be manufactured because of the thinner walls required. On the other hand, the Compacted Graphite Iron brings technological challenges for obtaining cast parts and also to machine them, because they normally reduce the tool lives during machining. This work s objective is to research the machinability of different compositions in order to obtain and alloy that can be used as a feasible alternative for manufacturing cylinder heads. The work consists, fundamentally, in the machinability evaluation of three cast iron alloys, Compacted Graphite Iron classes 450 and 350, and Grey Cast Iron class 300, through drilling tests. The machinability criterion used is the tool wear. / Nos últimos anos o ferro fundido vermicular tem conquistado um crescente espaço na indústria automobilística. Destina-se à fabricação de diversas peças automotivas, tais como discos de freio, coletores de escapamento e, principalmente, cabeçotes e blocos para motores. Sua maior resistência mecânica, em relação ao ferro fundido cinzento, possibilita a fabricação de motores com maiores pressões na câmara de combustão, portanto, mais eficientes e menos poluentes. Motores mais leves podem ser fabricados, em função das menores espessuras de parede necessárias. Por outro lado, o ferro fundido vermicular traz consigo desafios tecnológicos tanto para a obtenção da peça fundida quanto para a usinagem, uma vez que, normalmente, provoca redução da vida das ferramentas de usinagem. O presente trabalho objetiva pesquisar a usinabilidade de diferentes composições a fim de obter uma liga que possa ser utilizada como uma alternativa viável para a fabricação de cabeçotes de motor. O trabalho consiste, fundamentalmente, na avaliação da usinabilidade de três ligas de ferro fundido, sendo o vermicular da classe 450, da classe 350 e o cinzento da classe 300, e para tanto foram utilizados ensaios de furação de longa duração. Como critério de usinabilidade considerado foi utilizado o desgaste da ferramenta.