This study investigates the tool wear of advanced PVD TiALN/TiN multilayer coated end mill inserts when dry and semi-dry machining 4340 low alloy medium carbon steel. A factorial design of experiment setup consisting of two levels of speed, three levels of feed, two levels of depth of cut, and two levels of cutting conditions (semi-dry and dry) was used for the study. The combination of cutting conditions that gave the best response for different components of cutting force, cutting power, surface roughness and tool life were determined using MANOVA & ANOVA analysis and Tukey comparison of means test using MINITAB statistical software package. From a study of the Energy Dispersive X ray (EDX) analysis and primary back scatter images obtained from the worn out crater surface of the insert, it was observed that diffusion wear prevailed under both dry and semi-dry machining conditions. A tool life model was developed using multiple regression analysis within the range of cutting conditions selected. A model for flank wear progression was also developed using mixed effects modeling technique using S Plus statistical software package. This technique takes into account between and within work piece variations during end milling and produces a very accurate model for tool wear progression. This is the first time application of the mixed effects modeling technique in metal cutting literature.

Titanium and its alloy (Ti-6Al-4V) are widely used in aerospace industries because of their light weight, high specific strength, and corrosion resistance. This study conducted a comparative experimental analysis of the machinability of Ti-6Al-4V for conventional flood coolant machining and sustainable dry machining. The effect of cutting speed, feed rate, and depth of cut on machining performance has been evaluated for both conditions. The machining time and surface roughness were found to be lower in dry machining compared to flood coolant machining. The tool wear was found to be unpredictable, and no significant difference was observed for dry and coolant machining. In a comparison of all the parameters, sustainable dry machining was found to provide better performance in machining Ti-6Al-4V. This study also investigated the machinability of Ti-6Al-4V using coated and uncoated tungsten carbide tools under dry conditions. Tool wear is a serious problem in the machining of titanium alloys in dry conditions. Heat dissipation from the toolworkpiece interface a difficult challenge in dry machining, resulting in the alloying of the workpiece to the tool surface. Dry machining with the coated tool was comparatively faster, and resulted in less tool wear than uncoated tools. Using the Titanium aluminum nitride TiAlN coated carbide tool during dry machining provided a smoother surface finish with lower average surface roughness. The conclusion, therefore, is that the tool coating was found to be effective for the dry machining of titanium alloys.

The objective of this study is to develop a methodology to analyze the air quality and tool performance in turning process under near-dry condition. Near dry machining refers to the use of a very small amount of cutting fluid in the machining process. In order to implement the near dry machining technology, this dissertation develops the analytical models for both tool life and aerosol generation prediction. This research includes predictive models of cutting temperatures, cutting forces, tool wear progressions, and aerosol generation. The comparison of air quality and tool performance among dry machining process, near dry machining process, and flood cooling machining process is also presented. It is found that according to the selected cutting conditions in the model-based comparisons, the predicted cutting forces, cutting temperature and power consumption under near dry lubrication are reduced as high as about 30% compared with those in dry cutting but these predicted values are higher than those in wet cutting by about 10% under the same cutting conditions while the predicted tool wear land lengths are reduced by 60% compared with those in dry cutting but these values are higher than those in wet cutting about 1% under the same cutting conditions. However, the air quality for near dry machining with 12.5 ml/hr oil flow rate is worse than that for wet cutting due to different aerosol generation mechanisms.

L'industrie automobile cherche à réduire son utilisation des liquides de coupe en usinage pour des raisons économiques, environnementales et sanitaires. Les fabricants développent ainsi la démarche Minimum Quantity Lubrication qui vise à réduire au strict minimum l'utilisation des liquides de coupes en usinage. En l'absence de liquide de coupe, la stabilisation thermique de la pièce n'est plus assurée et des échauffements locaux apparaissent. Ces échauffements créent des déformations qui doivent être quantifiés et pris en compte afin d'assurer la conformité de la géométrie produite.Une démarche de modélisation de l'échauffement d'une pièce pendant l'usinage est présentée. Le modèle obtenu permet à la fois de quantifier la quantité de chaleur introduit dans la pièce pour des usinages simples et de simuler les déformations d'une pièce complexe lors de l'enchainement d'opération d'usinage. Cette quantification repose sur une méthode inverse. Elle est appliquée à des opérations de fraisage, perçage et taraudage d'un alliage d'aluminium AS9U3. Dans un second temps, une étude de l'influence de l'ordonnancement des opérations d'usinage d'un carter de boite de vitesses automobile sur la qualité de la géométrie produite est conduite. Cette étude illustre l'intérêt du modèle de simulation et des outils développés pendant la thèse. Enfin, les enjeux économiques et environnementaux de la technologie MQL seront abordés. / The application of MQL or dry machining in mass production becomes more and more accepted. Dry (MQL) machining is a very efficient solution to reduce the usage of cutting fluids and represents an effective measure for an environmental friendly production. However, these techniques do not benefit any more from the stabilization in temperature obtained with cutting fluids. More important and more heterogeneous increases of the temperature are observed. This leads to distortions of the work piece during machining which are necessary to be taken into account to maintain the geometrical quality of the manufactured surfaces.A model of the warm-up of a part during machining is presented. The obtained model allows to quantify heat introduced into the work piece for simple operations and to feign the distortions of a complex part when operations are enchained. This quantification is based on an inverse method. It is applied for reaming, drilling and tapping process for an aluminum alloy AS9U3. Secondly, a study about influence of operations organization is done. We use the model to quantify distortions an aluminum clutch case along machining. This study illustrates interest of the model and of tools developed during the PhD. In a last part, economic and environmental stakes of the MQL approach are discussed.

Orientador: Marcos Valerio Ribeiro / Resumo: 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) / Doutor

Increasing productivity is a constant demand for the manufacturing industry. Low-carbon-steel is one of the most commonly used ferrous materials in the part manufacturing market. Improving productivity as well as making the process eco-friendly by implementing a dry machining condition is the essential goal of this study. Built-up-edge (BUE) is often formed in the low-carbon-steel machining process, which, results in poor surface finish and short tool life. The high-speed-machining technique can be used to reduce the BUE formation and realize an increase in productivity. Cubic boron nitride (CBN) tools are most commonly used in hard turning and cast-iron machining at high cutting speeds. There are a limited number of studies regarding low-carbon-steel machining with CBN under a high-speed and with a dry machining condition. In this study, the investigation shows the preferable type of CBN tool and the wear mechanisms involved during finish turning operations of AISI 1018 under high speed and dry machining conditions. Test results show that a low CBN content with a TiCN binder and smaller grain size offers the best tool life and surface integrity of the final part. Currently manufacturers use coated carbide tools with a recommended cutting speed of 200-300m/min with coolant to complete the finishing process for turning low carbon steel parts. In this study, by implementing CBN tools under the dry condition at 500 m/min cutting speed (speed was selected from the preliminary test performed using the uncoated CBN from 500 to 1200 m/min), the buildup edge formation has been reduced, tool life was measured to increase by 307% compared to the benchmark tool (Coated Carbide), and surface finish was measured in the range of 0.8-1.6μm Ra. / Thesis / Master of Applied Science (MASc)

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.

Using of process liquids improves the procedure and results of machining, on the other hand, increases costs and raises some ecological and hygienic issues. In the work there is gradually analyzed mechanism of chip formation, progress and distribution of heat and thermal fields as well as economic and ecological aspects of dry machining and influence of dry machining on durability of tools. In the experimental part there are evaluated data which were measured during the drilling of cylindrical workpiece with regards to progress of workpiece thermal fields while using various kind of tool coating. In the final part there are stated recommendations for practice.

No description available.

Stainless steel is a metal material widely used in many industries because of its high tensile strength, toughness, and corrosion resistance. Machining stainless steel is challenging due to its high work hardening tendency, low thermal conductivity, and ductility of the material resulting in built-up edge formation. Machining stainless steel at lower cutting speeds must be performed with coolant, which adds to the cost of the process and increases concerns for the environment and the operator's health and safety. Industries such as the aerospace and die-mold industries demand high-speed machining to realize productivity targets. Therefore, a cermet tool material was selected for the present study because of its high temperature resistance, high bending strength, and fracture toughness. The study focused on investigating wear mechanisms and developing a coating on a cermet tool for dry high-speed machining stainless steel to increase tool life. The wear mechanisms of tools were investigated at a fixed cutting interval in relation to the tool's composition and microstructure. Scanning Electron Microscope (SEM) was used to study the microstructure and identify elements on the tool. X-ray diffraction (XRD) was used to identify the phases and concentrations of key elements on the tool. The new advanced in-house coating was developed with Super Fine Cathode (SFC) technology on a Kobelco AIP-20 Physical Vapour Deposition (PVD) coater. The micromechanical properties of the commercial coating and in-house coatings were investigated with the help of nanoindentation and scratch tests. Atomic Force Microscopy (AFM) and SEM were used to investigate the coating microstructure and surface topography. An Alicona variable focus 3D microscope was used to investigate wear volume and wear behaviour. It was discovered that various secondary carbides used by manufacturers to manufacture cermet tools change the microstructure, which affects the machining performance of the cermet tool material. Microchipping at the depth of cut (DOC) causes catastrophic notch wear. It was found that the developed in-house coatings were able to delay the initial wear (microchipping), which improved the tool's life by 318%. This research contributes to meeting the manufacturing industry's challenging demand for dry-high speed machining with reduced manufacturing costs. / Thesis / Doctor of Philosophy (PhD) / Cutting is the process of removing unwanted material from the bulk material to obtain the desired shape. Each metal material has unique mechanical properties that lead to various machining challenges. The cutting process is done with the help of a cutting tool that wears out during the process, and a coating layer is often used to protect the tool. Stainless steel 304 is a widely used material that is difficult to machine. This study includes a systematic approach to understanding the wear mechanisms of tools and existing commercial coatings during the dry machining of stainless steel 304. An in-house coating was developed and deposited on the selected cutting tool to protect it, reduce tool wear and extend its working life. The research results will help reduce machining costs by reducing tool and coolant costs and meet the current industry demand for dry high-speed machining. It will also reduce environmental impact by reducing waste and hazardous chemicals and addressing occupational health and safety concerns.