Tool Materials

Although there have been great advances in the development of cutting tool materials which have significantly improved the machinability of a large number of metallic materials, including cast irons, steels and some high temperature alloys such as nickel-based alloys, no equivalent development has been made for cutting titanium alloys due primarily to their peculiar characteristics. This paper reviews the main problems associated with the machining of titanium as well as tool wear and the mechanisms responsible for tool failure. It was found that the straight tungsten carbide (WC/Co) cutting tools continue to maintain their superiority in almost all machining processes of titanium alloys, whilst CVD coated carbides and ceramics have not replaced cemented carbides due to their reactivity with titanium and their relatively low fracture toughness as well as the poor thermal conductivity of most ceramics. This paper also discusses special machining methods, such as rotary cutting and the use of ledge tools, which have shown some success in the machining of titanium alloys. © 1997 Elsevier Science S.A.

The last decade has seen an increasing interest in the novel applications of electrical discharge machining (EDM) process, with particular emphasis on the potential of this process for surface modification. Besides erosion of work material during machining, the intrinsic nature of the process results in removal of some tool material also. Formation of the plasma channel consisting of material vapours from the eroding work material and tool electrode; and pyrolysis of the dielectric affect the surface composition after machining and consequently, its properties. Deliberate material transfer may be carried out under specific machining conditions by using either composite electrodes or by dispersing metallic powders in the dielectric or both. This paper presents a review on the phenomenon of surface modification by electric discharge machining and future trends of its applications.

A robust 3-D ®nite element model of a cutting tool is presented in this paper. The model takes into consideration the thermal and mechanical interactions at the tool/chip and tool/workpiece interfaces. Temperature-dependant material properties are incorporated in the model. The model was applied to the special case of the turning of Al/SiC particulate metal matrix composites, where high tool wear rates represent a challenge to the industry. The temperatures and stresses predicted by the model are in agreement with experimental measurements and tool wear observations. The wear patterns predicted by the model include crater wear, tool pitting and tool chipping. Thus, the model presented could be utilized in the selection of the tool material, geometry and cutting parameters that would result in the least tool wear, and hence helps to reduce machining costs and tool change down-time. Controlling tool wear is expected to enhance the surface integrity of the workpiece. #

The paper presents a review of original investigations on the surface modification of metallic materials with low energy (up to 40 keV), high current (up to 40 J/cm 2 ) electron beams of microsecond duration. Based on material research and on simulations of temperature and stress fields, ...

An experimental study on drilling of graphite/bismaleimide (Gr/Bi) titanium (Ti) stacks was conducted by using dierent cutter materials with a standard geometry to understand and characterize the process. The tool materials used were high-speed steel (HSS), high-speed cobalt (HSS-Co), and carbide. It was observed that at the interface of Gr/Bi±Ti, high temperatures induced material damage near and around the hole region. Dissimilar mechanical and thermal properties aected the tool life and allowed for increased matrix degradation and burr formation in Ti, regardless of the cutting tool material. As a result, fewer holes were produced when high spindle speeds and slow feeds were used. It was also found that carbide drills outperformed all other tools in terms of tool life, minimal surface damage, and heat induced damage on both workpiece materials. Ó

In the last decades, the improvement in the coatings of carbide tools and in the chemical and mechanical properties of tool materials, has caused the increase of tool working life in machining processes. This fact has allowed the use of the so-called dry machining technology and also machining with minimal quantity of lubricant. There are many important factors that justify the development of such technologies, including the high costs of refrigeration, the ecological damages caused by the use of lubricants, the increasing law demands, related to the preservation of the environment, workers' health, etc. The main objective of this work is to compare the performance of the uncoated and diamond coated carbide drills, using minimal lubrication (10 ml/h of oil in a flow of compressed air) and abundant soluble oil as a refrigerant/ lubricant in the drilling of aluminum-silicon alloys (A356). The results showed an irregular wear in the surface of the diamond coated drill and a decrease in the quality of the hole made by it, compared to the uncoated drill. Taking into consideration all the conclusions reached in this work, the most important one is that the performance of the process (in terms of forces, tool wear and quality of holes), when using minimal lubrication, was very similar to that obtained when using a high amount of soluble oil, with both, coated and uncoated drills. This conclusion proves the potential of using this technique in the drilling process of aluminum-silicon alloys. # 2002 Published by Elsevier Science B.V.

Titanium alloys have been widely used in the aerospace, biomedical and automotive industries because of their good strength-to-weight ratio and superior corrosion resistance. However, it is very difficult to machine them due to their poor machinability. When machining titanium alloys with conventional tools, the tool wear rate progresses rapidly, and it is generally difficult to achieve a cutting speed of over 60 m/min. Other types of tool materials, including ceramic, diamond, and cubic boron nitride (CBN), are highly reactive with titanium alloys at higher temperature. However, binder-less CBN (BCBN) tools, which do not have any binder, sintering agent or catalyst, have a remarkably longer tool life than conventional CBN inserts even at high cutting speeds. In order to get deeper understanding of high speed machining (HSM) of titanium alloys, the generation of mathematical models is essential. The models are also needed to predict the machining parameters for HSM. This paper aims to give an overview of recent developments in machining and HSM of titanium alloys, geometrical modeling of HSM, and cutting force models for HSM of titanium alloys.

The residual stresses that develop in fibre-reinforced laminates during autoclave processing while the laminate is confined to the process tool often lead to dimensional changes such as spring-in of angles and warpage of flat sections. A large number of experiments were performed to examine the effect of design and process parameters on spring-in and warpage of composite laminates with a symmetrical lay-up. The parameters studied include part angle, thickness, lay-up, flange length, tool material, tool surface, and cure cycle. This paper shows that both design and process parameters can have a significant effect on spring-in and warpage and that there are interactive effects between them. The paper also shows that spring-in of angled laminates is sensitive to the measurement technique as the measured spring-in often is compounded by warpage of flat laminate sections. #

Inconel 718 is one of a family of nickel based superalloys that are used extensively by the aerospace industry in the hot sections of gas turbine engines. The literature detailing the effects of varying operating parameters on tool life when machining nickel based superalloys is comprehensive, however, relatively little of this data refers to their effects on machined workpiece surface integrity and residual stress generation. Greater knowledge of the effects of operating parameters on surface integrity is critical to the acceptance of new cutting tool materials, tool geometries and strategies. The paper initially reviews prior work on the surface integrity achieved when turning Inconel 718. Following on from this a series of experiments evaluating the effects of varying cutting tool material, geometry, wear level and operating parameters are detailed. The results show that the largest influence on surface integrity was tool wear. Cutting with a worn tool resulted in greater microstructural deformation, microhardness changes and high surface tensile stresses. High tensile stresses were also formed in the surface layer when cutting with a coated tool, while cutting with an uncoated tungsten carbide insert at the same operating parameters produced deep compressive stresses beneath a reduced tensile layer.

The tool-using behaviors of wild chimpanzees comprise the most impressive assemblages and flexible repertoires of nonhuman material culture. We expand knowledge of the breadth and complexity of tool use in this species by providing the first descriptions of the form and function of two distinct tool sets used by chimpanzees in preying upon termites within the forests of the Goualougo Triangle, Republic of Congo. Further, we report the first application of remote video monitoring technology to record wild chimpanzee tool-using behavior. Based on tool assemblages recovered at termite nests, we hypothesized that chimpanzees were regularly visiting two forms of termite nests and using specific tools to extract termite prey depending on the structure of the nest. Six months of continuous remote video monitoring at six termite nests confirmed that chimpanzees use a tool set to puncture and fish at subterranean termite nests and another tool set to perforate and fish at epigeal (aboveground) nests. Our findings of strict adherence to tool forms at different nest types, tool material selectivity, repeated visits to nests with reusable wood tool assemblages, and differences in material culture between communities have broad implications for our understanding of the ecological and cultural factors that shape hominoid tool use.

Structural parts made of composites have frequently to be drilled in the aircraft industry. However, little is know about the interacting conditions between the drilling tool and the material, which may be multi-type and multi-size. This study proposes a model which links the axial penetration of the drill bit to the conditions of delamination (crack opening mode I) of the last few plies. Several types of tool/material contact conditions were analyzed and were compared with experimental measurements, and with a model taken from the literature. Our study shows a close correlation between experiment and calculation when the thrust force of the drill is modeled by taking into account the geometrical nature of the contact between the tool and a laminate composite material. Ó

Alumina based ceramic cutting tool is an attractive alternative for carbide tools in the machining of steel in its hardened condition. These ceramic cutting tools can machine with high cutting speed and produce good surface finish. The wear mechanism of these ceramic cutting tools ...

The eternal goal achieving optimum gear manufacturing results in a quick and flexible way can be obtained by efficient machine tools and thorough processes know how. Gear manufacturing is associated with complicated generating kinematics, chip formation and tool wear mechanisms. To capture quantitatively the tool wear progress and the cutting loads, empirical, analytical, numerical as well as FEM-based methods describing the chip geometry and predicting the tool life and cutting forces have been developed. The application of innovative tool materials and coatings, optimized tool geometries and appropriate conduct of reconditioning procedures contribute to the significant reducing of the manufacturing cost.

This study aims at investigating the effects of high-pressure jet assistance (HPJA) in rough turning of Inconel 718. A finite element (FE) model for orthogonal machining has been developed in order to reach additional data, compare trends to the experimental ones and understand the influence of the jet on the cutting process. Mechanical and thermal loads induced by the jet are considered. Consequences on the primary and secondary shear zones, chip formation and tool rake face have been studied on a whole pressure range (30-130 MPa) and compared to dry cutting. It is shown that the jet is able to decrease the cutting forces, chip radius and tool-chip contact length. Contact pressure and temperature fields on the cutting tool are also reduced as well as the sticking part of the contact zone. Authors confirmed that the effects of convection are able to change and even amplify the influence of the pure mechanical load induced by the jet.

By virtue of their characteristics, the applications of composite materials based on carbon ®bre reinforced plastic (CFRP) have been increasing considerably. Thus new manufacturing process and production techniques must be developed to ensure high precision and good surface quality of the components. As a result of this manufacturing scenario, it is necessary to study the machining process. This work reports practical experiments in turning, to study the performance of different tool materials such as ceramics, cemented carbide, cubic boron nitride (CBN), and diamond (PCD). The results show that only diamond tools are suitable for use in ®nish turning. An optimisation methodology was used in rough machining to determine the best cutting conditions. The tests were carried out with cemented carbide tool at various cutting speeds. In the optimisation methodology were used the cutting length as the tool replacement criterion and some parameters were monitored such as the feed and cutting forces that can used be used as a safety system. Finally, it is concluded that the optimisation of the cutting conditions is extremely important in the selection of the tools and cutting conditions to be used in the CFRP manufacturing process. # 1999 Elsevier Science S.A. All rights reserved.

Cryoprocessing, a supplementary process to conventional heat treatment process, is the process of deep-freezing materials at cryogenic temperatures to enhance the mechanical and physical properties of materials being treated. The execution of cryoprocessing on cutting tool materials increases wear resistance, hardness, and dimensional stability and reduces tool consumption and down time for the machine tool set up, thus leading to cost reductions. The effects of cryoprocessing on tool steels and carbides, metallurgical aspects including reduced amount of retained austenite, precipitation of η-carbides, phase change in carbides, improvement in wear resistance, and applications are reviewed for manufacturing industry. Although it has been confirmed that cryogenic processing can improve the service life of tools, the degree of improvement experienced and the underlying mechanism remains ambiguous. The steps involved in cryoprocessing are critical enough to account for the significant incongruity in posttreated performance.

The paper initially reviews prior work on the influence of operating parameters on tool life when milling Inconel 718. Following this review, experimental work is described which evaluates the effect of varying feed rate/chip thickness, immersion ratio (radial depth of cut), tool material and geometry on the tool life, tool wear and productivity obtained when end milling Inconel 718.

Generating computer animation involves two interwoven components. The first component is the set of tools (tools) used to generate and render computer animation. Tools consist of software and hardware that allow the creation of abstract geometric models, modification of these models over time, as well as their rendering. The second component is the sequence of instructions to be carried out

Design is a rich domain in which to investigate barriers and biases in computersupported communication because it involves many different modes of communication in socialtechnical contexts. This chapter briefly describes different design approaches. It analyzes the biases and barriers of two different types of design communities: communities of practice and communities of interest. To address the communication challenges between diverse design communities, boundary objects are needed to establish common ground and shared understanding in the context of complex design tasks. We explore the unique possibilities that computational media have to support our conceptual framework. Our work is based on the fundamental belief that there is no media-independent communication and interaction-that tools, materials, and social arrangements are always involved in some way in these activities. The possibilities and the practice of design are functions of the media with which we design. We present examples of such environments from our work.

The high strength to density ratio of titanium alloys coupled with excellent corrosion resistance even at elevated temperatures make them ideal for aerospace applications. Moreover, the biocompatibility of titanium also enables its widespread use in the ...

This paper describes the wear mechanism and tool life when machining Hastelloy C-22HS with coated carbide. The experiment was conducted using four different cutting tool materials under wet condition -namely, Physical Vapor Deposition (PVD) coated with TiAlN; TiN/TiCN/TiN; Chemical Vapor Deposition (CVD) coated with TiN/TiCN/Al 2 O 3 ; and TiN/TiCN/TiN -to study the tool behavior, in terms of wear and tool life machining of Hastelloy C-22HS. Tool failure modes and wear mechanism were examined at various cutting parameters. Flank wear, chipping, notching, plastic lowering at cutting edge, catastrophic and wear at nose were found to be the predominant tool failure for the four types of cutting tools, especially with CVD tools. Attrition/adhesion, oxidation and built-up edge (BUE) are the wear mechanisms observed in all cutting tools. The results obtained indicated that PVD cutting tools performed better than CVD cutting tools, in terms of tool life with current parameters.

In the beginning, metalworking fluids consisted of simple oils applied with brushes to lubricate and cool the machine tool. As cutting operations became more severe, metalworking fluid formulation became more complex. There are now several types of metalworking fluids in the market and the most common can be broadly categorized as cutting oils or water-miscible fluids. In this paper, attention is focused on recent research work on formulation and application of vegetable oil-based metalworking fluids in turning process. In addition, the performances of various vegetable oil-based metalworking fluids based on some process parameters such as thrust force, surface roughness, temperature developed at the tool chip interface, and tool wear during turning process using different tool materials were highlighted. © 2012 Springer-Verlag London.

http://link.springer.com/article/10.1007/s00170-012-4607-0

Surface quality is one of the most impellent customer requirements in machining. The main aspect of surface quality on machined parts is probably surface integrity, such as roughness and residual stresses. In particular, residual stresses in the machined surface and subsurface are affected by tool geometry, material and machining parameters. These residual stresses can have significant effects on the service quality and the component life; they can be determined by either empirical or numerical investigations for the selected configurations; however, they are expensive procedures. The problem becomes more difficult if the aim is the inverse determination of the cutting conditions which correspond to a requested residual stress profile, inside the machined material. This paper presents a predictive hybrid model based on the artificial neural networks (ANNs) and finite element method (FEM) that can be used for both forward and inverse prediction. The former is able to determine a residual stresses profile corresponding to a given tool, material and process conditions, the latter is able to determine these conditions when a constraint on the residual stresses distribution is given. Three layer neural networks were trained basing on selected data from numerical investigations on hard machining of 52100 bearing steel, and then validated with data obtained by experiments. Prediction errors range between 4% and 16% for the whole data set, both for forward analysis and inverse process design, showing that this hybrid ANN-FEM based approach provides a robust framework for 52100 machining analysis.

Approximately two-thirds of all the superalloys produced are consumed by the aerospace industry for the manufacture of jet engines and associated components, mainly in the hot end of aircraft engines and land-based turbines. The remaining third of superalloy consumption is used by the chemical, medical and structural industries in applications requiring high temperature properties and/or exceptional corrosion resistance. Ability to retain high mechanical and chemical properties at elevated temperatures make superalloys ideal materials for use in both rotating and stationary components in the hot end of jet engines. These materials as well as structural ceramic and hardened steels pose formidable challenges for cutting tool materials during machining, hence they are referred to as difficult-to-cut. The basic difference between rotary cutting and conventional cutting is the movement of the cutting edge in addition to the main cutting and feed motions. Self-propelled rotary tools (SPRT) employs round inserts rotating continuously about its axis as a result of the driving motion impacted by the cutting force, thus minimising the effect of thermal energy along the entire edge and preventing excessive heating of a particular portion of the insert edge. Major benefits provided by SPRT include several hundred-fold increase in tool life, lower cutting temperature, higher metal removal rate, generation of fine surface finishes due to the circular cutting edge and improved machinability of difficult-to-cut materials such as nickel and titanium base alloys. Extremely low rate of flank wear can be obtained when machining aerospace superalloys, particularly titanium alloys, even at higher speed conditions with very negligible or no effect on the machined surfaces. This paper will provide an overview of developments in rotary tools, the principles of rotary cutting, structure and design of SPRT, factors influencing rotary tool life and detail information of practical machining data as well as analysis of tool failure modes and tool wear mechanisms in comparison to conventional (fixed tool) machining technique.

The 'Canadian prairies' represent one of the world's great breadbaskets, supplying people all over the world with agricultural commodities ranging from various grains, through legumes and oilseeds, to both grain and grass-fed meat products. However, the expansion and intensification of Canadian agriculture in the last century has significantly altered the structure and degraded the function of prairie ecosystems. This, combined with climate change, has put the ecological sustainability of the region at risk and raises questions about the region's ability to continue supporting millions of distant consumers. We use variants of two existing sustainability assessment tools, material flows analysis (MFA) and ecological footprint analysis (EFA) to estimate the terrestrial ecosystem area and other physical inputs used on the Canadian prairies to satisfy export demand and to link this production to documented processes of ecological degradation. We discuss the implications of this interregional framework for impact analysis and conclude that, in a globalizing, ecologically full-world, trade-dependence implies previously-ignored risks to both importers and exporters. The results underscore the importance for all countries to protect or restore their own natural capital assets and enhance their self-reliance. Citizens and their governments, particularly of countries that have become irreversibly import-dependent, have a direct interest in ensuring that the ecosystems that support them are sustainably managed, wherever in the world the latter may be located.

Inappropriate machining conditions such as cutting forces cause tool failures, poor surface quality and worst of all machine breakdowns. This may be avoided by using optimal machining parameters, e.g. feed-rate, and continuing to monitor it throughout the machining process. To optimize feed-rate, we propose a system that consists of an optimisation module, a process control module and a knowledge based evaluation module. STEP-NC is the underlying data model for optimisation. Given the nominal powers, the cutting force can be estimated based on the higher-level production information such as workpiece properties, tool materials and geometries, and machine capabilities. The main function of the Process Control module is process monitoring and control. The output is the desired actual feed-rate. Finally, the actual feed-rate is recorded and evaluated in the Knowledge Based Evaluation module.

Forming tools manufacturers have extensively incorporated high-speed milling technology for the finishing of large punch or die tools. The main objective is to achieve a good surface quality directly form machining, without any additional, tedious, manual work. Currently, new advanced high-strength steels (AHSS) are being used for car body parts. In this case, there are two special changes related to the forming tools: a higher proportion of harder surfaces on the working area, and long try-out iterations, due to their great springback. Tempered surfaces and insert blocks harder than 60 HRC are needed to withstand the forming charges with a good working life expectancy. From this, two problems arise with regards to highspeed finishing: first, the deflection of the tool due to the cutting forces, which can produce unacceptable dimensional errors; and second, in the same finishing operation, zones with sharp changes in hardness must be machined with the same CNC program and cutting tool. The key to solving both problems will be the use of newly developed utilities in the preparation stage, and the elaboration of CNC programs using CAM software. In the first case, the deflection of tool is dealt with by a milling model which obtains the values of cutting forces. This model characterises the couple tool/material with six coefficients, which are previously obtained for ball-end milling tools and base die materials. Inputs provided by the CAM user include feed per tooth, and radial and axial depths of cut. The problem of surfaces with areas of different hardness and poorly defined boundaries is solved with a special postprocessor coded in C language. Once the CAM user has defined (on the CAD model) the theoretical boundaries of the tempered areas, the insert blocks or the deposition material areas, this utility includes changes of the programmed feed function in the CNC program.

The present study describes an experimental research on surface modification during electrical discharge machining (EDM) by depositing a hard layer over the work surface of C-40 grade plain carbon steel using specially prepared powder metallurgy compact tools. The investigated process parameters were composition, compaction pressure, sintering temperature, pulse on-time, peak–current setting, and duty factor. Measurements of deposited layer thickness, mass transfer rate, tool wear rate, surface roughness and microhardness were undertaken on the EDM-ed specimens. Different studies like X-ray diffraction, optical microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were carried out to ascertain the characteristics of the deposited layer on the work surface. These analyses confirmed the presence of the tool materials in the work surface layer. At first, an L-16 orthogonal array was applied as Taguchi DOE technique and the ANOVA was done to study the effects of pertinent process parameters. An optimum condition was achieved using overall evaluation criteria. Later on, a detailed study was carried out to get a smooth and regular deposition of material. The characterization of the deposited layer is presented. The deposited layer with a wide range of average layer thickness of 3–785 μm, enriched with tool materials (W and Cu) and with the formation of tungsten carbide, and having microhardness of 9.81–12.75 GPa at the hardest zone was successfully deposited over the work surface.

Silicon is a representative operational material for semiconductor and micro-electronics. In certain MEMS applications, it is required to fabricate three dimensional channels and complex pattern on silicon substrate. Such features are typically fabricated by photolithography and chemical etching. These processes have low productivity and have certain other limitations. Therefore, a viable switch-over from nontraditional fabrication processes to traditional machining is highly desired for improved productivity in high-mix low-volume production. However, machining of silicon by traditional process is extremely difficult due to its high brittleness. Even very small forces produced during machining can cause brittle fracture on silicon surface resulting in deteriorated surface quality. The fundamental principle in machining of a brittle material such as silicon is to achieve material removal through plastic deformation rather than crack propagation. This paper presents the experimental results of ductile-mode machining of silicon by micro ball end-milling. The workpiece surface was inclined to the rotational axes of the cutter to improve the surface finish. It was established experimentally that 15-m deep, fracture-free slots can be machined on silicon wafer by micro ball end-milling if the feed rate is below a certain threshold. The influence of several machining parameters on the roughness of machined-surface was also investigated. Cubic boron nitride (CBN) is presented as much economical alternative tool-material to single-crystal diamond for machining silicon in ductile-mode.

In the modern manufacturing of sophisticated parts with 3D sculptured surfaces, die and mold making operations are the most widely used machining processes to remove unwanted material. To manufacture a die or a mold, many different cutting tools are involved, from deep hole drills to the smallest ball nose end mills. Since the specification of each tool is very different from each other, each mold or die is specific with their complicated shapes and many machining rules exist to consider, a great deal of expertise is needed in planning the machining operations. An expert system (DieEX) developed for this purpose is described in the present work. The geometry and the material of the workpiece, tool material, tool condition and operation type are considered as input values and various recommendations about the tool type, tool specifications, work holding method, type of milling operation, direction of feed and offset values are provided. r

This paper reports on the tribological properties of commercial Cr-N physical vapour deposition (PVD) processes for enhanced mechanical protection of forming and machining tools. The study is carried out on conventional tooling materials as substrates, i.e. high speed steels (M2) and cemented tungsten carbide. Electron beam (EB), magnetron sputtering (MS) and cathodic arc (CA) commercial Cr-N PVD processes from three different EU coating centers/companies are evaluated in terms of their tribological behaviour by standard characterization techniques for material properties: surface hardness and roughness, film adherence strength and wear resistance under sliding conditions. The results are discussed on the basis of their current applications and their influence on tool performance for manufacturing processes. Moreover, film tribological performance is correlated with their microstructural properties as obtained by electron microscopy and X-ray diffraction. In terms of surface hardness and adherence strength, CA Cr-N seems to outperform EB and MS coatings. However, EB and MS exhibit enhanced surface finish which might be more appropriate for some applications.

a b s t r a c t WC-Co cemented carbides are a class of hard composite materials of great technological importance. They are widely used as tool materials in a large variety of applications that have high demands on hardness and toughness, including mining, turning, cutting and milling. The HVOF (high velocity oxygen fuel) technology has been very successful in spraying wear resistant WC-Co coatings with higher density, superior bond strengths and less decarburization than many other thermal spray processes, attributed mainly to its high particle impact velocities and relatively low peak particle temperatures. The degree of decomposition and bond strength is directly related to relevant particle parameters such as velocity, temperature and state of melting or solidification. These are consecutively related to process parameters such as powder particle size distribution, carrier gas flow rate, and fuel type employed. To obtain detailed particle data important for thermal spraying, mathematical models are developed in the present paper to predict the particle dynamic behavior in a liquid fuelled HVOF thermal spray gun. The particle transport equations are coupled with the three-dimensional, chemically reacting, turbulent gas flow, and solved in a Lagrangian manner. The melting and solidification within the particles as a result of heat exchange with the surrounding gas flow is solved numerically. The in-flight characteristics of WC-Co particles are studied and the effects of carrier gas parameters on particle behavior are examined. The results demonstrate that WC-Co particles smaller than 5 lm in diameter undergo melting and solidification prior to impact while most particles never reach liquid state during the HVOF thermal spraying. The flow rate of carrier gas has considerable influence on particle dynamics as well as deposition on substrate. At higher flow rate the powder particles are redirected further away from the substrate center, while smaller flow rate results in better heating, higher impact velocity and deposition closer to the substrate center.

An important trend in material research is to predict mechanical properties for a new titanium alloy before committing experimental resources. Often the prediction of mechanical properties of these alloys changes depending on their chemical composition and processing methods. Therefore, modeling the relationship between composition and property is crucial to the engineering. This study employs an adaptive fuzzy-neural network approach to predict the mechanical properties of titanium alloys. In adaptive fuzzy-neural network, to reduce the complexity of fuzzy models while keeping good model accuracy, a fuzzy clustering algorithm and a back-propagation learning algorithm are introduced to improve the accuracy of the simple model. For purpose of constructing this model, experimental results for 57 specimens with 14 different chemical compositions were gathered from the literature. The chemical composition contents were employed as the inputs while yield strength, tensile strength, elongation and reduction of area, which were employed as the outputs. Thus, the model can be trained by using the prepared training set. After training process, the testing data were used to verify model accuracy. It is found that there is insignificant difference between predict results and experimental value and the maximum relative error is less than 9%. It proved that the predictive performance of the clustering-based adaptive fuzzy-neural network modeling is available and effective in simulating the composition content and predicting the mechanical properties of titanium alloys.

Purpose: The goal of this project is development of the contemporary gradient materials using the powder metallurgy methods to ensure the required properties and structure of the designed material. Design/methodology/approach: The materials were fabricated with the conventional powder metallurgy method consisting in compacting the powder in the closed die and finally sintering it. Forming methods were developed for the HS6-5-2 high-speed steel and non-alloy steel powders, making it possible to obtain materials with three layers, and later after their further modification with six layers in their structure. Findings: It was found out basing on the microhardness tests that hardness of test pieces grows along with the sintering temperature and with carbon content in the interface and non-alloy layers. It was also observed that porosity decreases along with the carbon content in these layers. It was found out, basing on the comparison of structures and properties of the compacted and si...

In the aero engine industry alternative manufacturing processes for load carrying aero engine structures imply fabrication. The concept of fabrication involves simple forgings, sheet metals and small ingots of e.g. titanium alloys which are welded together and heat treated. In the concept phase of the product development process, accurate evaluations of candidate manufacturing processes with short lead times are crucial. In the design of sheet metal forming processes, the manual die try out of deep drawing tools is traditionally a time consuming, expensive and inexact process. The present work investigates the possibility to design hot forming tools, with acceptable accuracy at short lead times and with minimal need for the costly die try out, using finite element (FE) analyses of hot sheet metal forming in the titanium alloy Ti-6Al-4V. A rather straightforward and inexpensive approach of material modelling and methods for material characterisation are chosen, suitable for early evaluations in the concept phase. Numerical predictions of punch force, draw-in and shape deviation are compared with data from separate forming experiments performed at moderately elevated temperatures. The computed responses show promising agreement with experimental measurements and the predicted shape deviation is within the sheet thickness when applying an anisotropic yield criterion. Solutions for the hot forming tool concept regarding heating and regulation, insulation, blank holding and tool material selection are evaluated within the present work.

This paper presents a quantitative analysis of a polycrystalline cubic boron nitride tool material by electron energy-loss spectroscopy spectrum imaging acquired in dual range mode. Having both the low-loss and core-loss regions acquired nearly simultaneously provides the advantage of accurate corrections for thickness effects and thus the possibility to perform quantification calculations. This has resulted in extracted bonding maps with areal (atoms/nm 2 ) or volumetric (atoms/nm 3 ) densities. Spectroscopic signatures in the low-loss and core-loss energy ranges, of the elements (Al, B, C, N, Ti and O) present in the existing phases, were studied and used when extracting the element specific bonding maps by the multiple linear least squares fitting procedure. Variations of elemental concentrations across the investigated area were determined, despite of phase overlap in the beam direction or energy overlaps in the EELS spectrum. Moreover, the surface oxidation of Ti(C,N) and AlN as well as the amorphisation of α-Al 2 O 3 is discussed.

The characteristics of carbon fibre reinforced plastics allow a very broad range of uses. Drilling is often necessary to assemble different components, but this can lead to various forms of damage, such as delamination which is the most severe. However, a reduced thrust force can decrease the risk of delamination. In this work, two variables of the drilling process were compared: tool material and geometry, as well as the effect of feed rate and cutting speed. The parameters that were analysed include: thrust force, delamination extension and mechanical strength through open-hole tensile test, bearing test and flexural test on drilled plates. The present work shows that a proper combination of all the factors involved in drilling operations, like tool material, tool geometry and cutting parameters, such as feed rate or cutting speed, can lead to the reduction of delamination damage and, consequently, to the enhancement of the mechanical properties of laminated parts in complex structures, evaluated by open-hole, bearing or flexural tests.

The use of multi-axis high-speed milling has increased in different industrial sectors such us automotive, aeronautical, and the manufacturing of complex moulds. This trend can be observed in last technical fairs and catalogues of main machine tool manufacturers.

It has been demonstrated in the paper that the deposition of the multi-layer and multi-component coatings with the PVD technique using cathode arc evaporation CAE process, on tools made from cemented carbides, results in the increasing of coating hardness and the improvement of their adhesion to the substrate, comprising with the single-or multi-layer coatings deposited using the PVD or CVD methods on the same substrate materials, deciding improvement of the working properties of cutting tools coated with the TiN + mono or multi (Ti, Al, Si)N + TiN system coatings, compared with coatings developed on the same sintered tool materials, but uncoated or coated with simple coatings. The paper presents the results of the structural examinations, mechanical tests and working properties of thin wear resistant coatings of the TiN + mono or multi (Ti, Al, Si)N + TiN type, deposited onto the substrate from the cemented carbides. Structural examinations of the applied coatings and their substrate was made using the SEM and on the light microscope. The evaluation of the adhesion of the deposited coatings onto the cemented carbides was done using the scratch tester. Cutting properties of the investigated materials were determined based on the technological continuous cutting tests of the C45E steel. Microhardness tests of the deposited coatings were made on the ultra-microhardness tester. Surface roughness tests were done either before depositing the coatings and after completing the PVD process.

In this work, the fabrication of bulk TiC 0.7 /TiB 2 nanostructured composites through metastable transformation processing is investigated by taking advantages of two non-conventional powder metallurgy methods. First, the highly metastable TiC 0.7 /TiB 2 agglomerated powders are synthesized by the so-called self-propagating high-temperature synthesis (SHS), followed by rapid quenching. Then, the spark plasma sintering (SPS) method is adopted to consolidate the SHSed powders.

In the present research work, the effect of several process parameters on the machining characteristics of pure titanium (ASTM Grade-I) has been reported. The machining characteristics that are being investigated are tool wear rate and the quality of the machined surface in terms of the surface finish. The mechanism of material removal was has also been correlated with the machining conditions. Four different process parameters were undertaken for this study; Tool material, abrasive material, grit size of the slurry used and power rating of the machine. The optimal settings of parameters are determined through experiments planned, conducted and analyzed using Taguchi method. The significant parameters are also identified and their effect on tool wear rate and surface roughness is studied. The results obtained have been validated by conducting the confirmation experiments. / 235 responses from the raw data help in analyzing the trend of the performance characteristic with respect to the variation of the factor under study. The level average response plots based on the S/N data help in optimizing the objective function under consideration. The peak points of these plots correspond to the optimum condition. The main effects of raw data and those of the S/N ratio are shown in (tool wear rate) and .

Seven types of coffee were prepared by four methods. Three of them -simple coffee infusion, preparation in ibrick and moka pot -are very often used to prepare coffee at home. The fourth one -a single-cup filter is typical for Vietnam. Cookware used for each method was made from glass, aluminium, stainless steel and two types of alloys. Amounts of Al leaching to coffee infusions were determined. On average, the highest amount of Al was in coffee infusions brewed in aluminium single-cup filter, and the lowest in infusions prepared by simple extraction. Other brewing methods in combination with different tool materials resulted in similar Al content. The type of brewing method significantly influences the Al content in final infusion. Aluminium content varies in infusions in relation to the method of choice, especially when using single-cup filter. Despite the fact that coffee is considered to be a poor source of Al for humans, in some cases, Al content in infusions can even reach the values reported for tea infusions.

Titanium is known as the metal of the future because of its excellent combination of properties such as high specific strength, low thermal conductivity, and high corrosion resistance. There is a critical need for developing and establishing cost-effective methods for the machining of titanium, especially in terms of tool-wear optimization. This paper addresses the application of ultrasonic machining, an impact machining process for the cost-effective machining of commercially pure titanium (ASTM Grade-I) and evaluation of tool-wear rate under the effect of different process parameters. Tool material, abrasive material, slurry concentration, abrasive grit size, and power rating of the ultrasonic machine were included as the input factors in this investigation. The optimal settings of these parameters were determined through experiments planned, conducted, and analyzed using the Taguchi method. The significant parameters contributing most to the variation in tool-wear rate were identified and the results obtained were validated by conducting the confirmation experiments. Thereafter, the outcome of the Taguchi model has been used for developing a micro-model for tool-wear rate (TWR); using Buckingham’s pie theorem. A comparison of the experimental results obtained assists in the validation of the model.

AbstrAct Purpose: The purpose of this research paper was to analyze the surface roughness produced by turning process on hard martensitic stainless steel by Cubic Boron Nitride cutting tool. The work piece material was hard AISI 440C martensitic stainless steel. Design/methodology/approach: The experiments were designed using various operating parameters like cutting speed, feed rate and depth of cut. These operating parameters are predominantly used in carrying out the experiments. Findings: Low surface roughness was produced at cutting speed of 225 m/min with feed rate of 0.125 mm/rev and 0.50 mm depth of cut (doc).However, moderate cutting speed of 175 m/min under above feed rate and doc is an ideal operating parameters taking flank wear in to account. Research limitations/implications: While searching for references in turning of martensitic stainless steel, very limited journals are available, but very few literatures are available on turning of AISI 440C hard martensitic stainless steel which was a constraint. Practical implications: The turning of hard martensitic stainless steel brings interesting information on surface roughness, tool wear etc. and further can be extended to turn with different cutting tools. Originality/value: The value of the research work lies in using the results by other researches. The result will upgrade the knowledge about the influence parameters on surface roughness especially on martensitic stainless steel especially on martensitic stainless steels.

In this study, the machinability of austempered ductile iron (ADI) having a ferritic structure was examined. For this purpose, three types of ductile iron materials (as cast, ADI-250, ADI-375) and two different types of cutting tool materials (ceramics and cermet) were used. To emphasize the role of austempering process, ductile iron (DI) specimens are first austenitized in salt bath at 900°C for 120 minutes after which they are quenched in salt bath at 250°C (ADI-250) and 375°C (ADI-375) for 120 min. Machining tests were carried out at various cutting speeds (100-500 m/min) under the constant depth of cut and feed rate. The performance of both ceramic and cermet tools were evaluated based on the workpiece surface roughness and flank wear. Wear conditions of the cutting tools were characterized by scanning electron microscope. The results point out that the lower austempering temperature results in increasing of the cutting forces, while better surface roughness is obtained. Additionally, the results indicate that the tool wear occurs mainly on the flank face. However, higher cutting speed results in chipping formation in cermet cutting tool.