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Coated polycrystalline cubic boron nitride (PcBN) tools are increasingly used for industrial applications with stringent requirements. However, information on the mechanical integrity of these systems is quite limited. Within this context, the adhesion strength of two TiN/TiAlN-coated and microstructurally different PcBN substrates – high- and low-cBN content grades with metallic and ceramic binders, respectively – is investigated by means of Rockwell C indentation testing. In doing so, special attention is paid to substrate microstructure effects on emergence and evolution of damage as applied load is increased. For both coated systems, it is found that damage scenario evolves from early adhesive delamination within the contact area towards radial cracking and spalling outside the residual imprint. However, critical loads for transition between damage stages are discerned to depend on microstructural assemblage of the substrate. Higher resistance to radial cracking and delamination is exhibited by the high cBN-content grade, in agreement with its higher hardness and toughness. Failure micromechanisms associated with cracking and spalling are similar for both coated-PcBN systems. Very interesting, delamination outside the residual imprint is determined to be of cohesive nature within the substrate, an experimental fact resulting from interaction among indentation-induced radial, cone-like and lateral fissures in PcBN.

In this research work, we have found that tool wear rate of the materials of high-speed steel and Stainless steel of 440C Grade which are having optimum composition of carbon and other constituents. Here we have expounded the distinguishing characteristics of high-speed steel and Stainless Steel in respect to the tool wear. Subsequently, we have carried out heat treatment process, where two machined specimens were kept inside the muffle furnace once it attained required temperature, it was maintained at that temperature for a certain period of time and then cooled back to room temperature, we have conducted hardness test, tool wear test. In addition to these cutting operations have performed over mild steel workpiece.

Interrupted cutting operations, such as milling, produce fluctuating tool temperatures which directly affect the process outputs. Thus, prediction of cutting tool temperatures enables process planning, selection of materials for tool substrate and coating layers, and tool geometric design for improved productivity in machining operations. Theoretical analysis of temperature is a cost effective way to predict the tool temperatures. Considering the industrial needs, a theoretical model should be fast, easy to implement, and reliable. To that end, a novel hybrid model, which assembles analytical and numerical methods, is proposed in this study. This novel transient thermal model simulates the interrupted cutting with coated cutting tools. The proposed model includes an analytical heat flux calculation at the tool-chip interface considering the sticking-sliding contact behavior. The determined heat flux is, then, used to perform a numerical solution of the transient heat conduction problem in the cutting tool geometry with temperature-dependent thermal properties. The developed model is validated with experimental results found in literature under different cutting conditions. The results show that the model can predict the maximum temperatures generated in a thermal cycle with an accuracy of 2–10%. Thus, the proposed model can be further used to determine the process parameters, properties of coating layers, and tool geometric design. Publisher's Version

In this study, the effect of adding nanosize additive to glass fiber reinforced composite plates on mechanical properties and surface milling was investigated. In the light of the investigations, with the addition of MWCNTs additive in the composite production, the strength of the material has been changed and the more durable composite materials have been obtained. Slots were opened with different cutting speed and feed rate parameters to the composite layers. Surface roughness of the composite layers and slot size were examined and also abrasions of cutting tools used in cutting process were determined. It was observed that the addition of nanoparticles to the laminated glass fiber composite materials played an effective role in the strength of the material and caused cutting tool wear.

Carbon fiber reinforced polymer (CFRP) is widely used in high-tech industries because of its interesting characteristics and properties. This material presents good strength and stiffness, relatively low density, high damping ability, good dimensional stability, and good corrosion resistance. However, the machinability of composite materials is complex because of the matrix/fiber interface, being a challenging machining material. The CFRP milling process is still necessary to meet dimensional tolerances, the manufacture of difficult-to-mold features like pockets or complexes advance surfaces, finish the edges of laminated composites, or drill holes for the assembly of the components. Besides, the demand for low-cost, reconfigurable manufacturing systems of the industry demonstrates that the application of industrial robots (IRs) in the CFRP milling process becomes an alternative for providing automation and flexibility. Therefore, the objective of this work is to evaluate the performance of the low payload IR KUKA KR60 HA in a milling experiment of CFRP, which indicates its potential application as an alternative to milling process. Furthermore, the influence of the cutting tool geometry as well as the cutting parameters in the machining behavior with IRs is evaluated.

The problem of optimal cutting of honeycomb blocks is considered in the article. The urgency of using irregular shapes application cutting from honeycomb blocks made of modern composite materials is substantiated. The problem is to obtain a cut of a given shape from honeycomb blocks. The optimal cutting plane of the single cell face of a honeycomb block is found on the basis of calculations for the stability and stretching force in adjacent faces applying a finite element method. The problem of obtaining faces and nodal points of a honeycomb block when calculating the coordinates of the optimal cut points of a real honeycomb block using machine vision methods. The most suitable algorithms, a part of the OpenCV library, are considered. The authors decided to develop their own algorithm for recognizing an irregular cellular structure since the existed algorithms did not solve the stated problem. As opposed to existing algorithms, the proposed one finds all the nodal points and faces even on the deformed sections of the honeycomb block avoiding false faces. The method helps to find coordinates of all nodal points and determine the connection of adjacent points with a face. As a result, real faces, not perfect geometrically, are replaced by line segments. The test result proves its correctness and practical applicability. The proposed method solves an optimal cutting problem of aluminum honeycomb block. It should be noted that the proposed method is customizable and can be applied to any honeycomb or cellular panels.

Laser irradiation de-coating is a promising new approach for effective coating removal of cutting tools. While this method has demonstrated feasibility for conventional coatings, its use and efficacy on lubricant coating is however yet to be ascertained. This paper reports on the results of excimer laser de-coating of hard DLC from DLC-coated tungsten carbide (WC) substrates. A range of fluence and pulse was studied to evaluate the effectiveness of the de-coating process. Result shows that laser parameters of 7 J/cm2 fluence, 400 pulse and 25 Hz frequency were found to yield optimum results in removing hard DLC coating of 3.2 μm thickness from WC substrates. The experimental work indicated successful laser de-coating of hard DLC coating without noticeable damage to the WC substrate. The capability of this new de-coating process is significant in the aerospace industry as it could facilitate re-grinding and recoating of drills thereby improving economics of manufacturing. The process windows could also be applied in the removal of DLC from other cutting tools and applications.

This study investigated the effects of the cryogenic treatment on cutting tool performance in the turning of AISI H11 steel. In the experiments, TiCN/Al2O3/TiN-coated tungsten carbide tools were used. Shallow cryogenic treatment was applied for 6 hat -80 degrees C (SCT6), deep cryogenic treatment at -196 degrees C for 6 h (DCT6), and deep cryogenic treatment at -196 degrees C for 24 h (DCT24). Turning tests were conducted at three cutting speeds (200, 240, and 280 m/min), three feed rates (0.15, 0.18 and 0.21 mm/rev), and a 0.6-mm depth of cut under dry cutting conditions. Experimental results showed that the cryogenic treatment increased the abrasion resistance of the cutting tool. The best cutting tool wear and surface roughness performance was obtained with the DCT24 tool. As a result of the tool life test, DCT24 tool wore 14.5% less than U tool. In terms of surface roughness, DCT24 tool improved up to 16.5% compared to the U tool. Moreover, it was determined that the cryogenic treatment provided an increase in the hardness of the cutting tools. The highest hardness increase also occurred in the DCT24 tool (10.87%). In addition, cryogenic treatment types were optimized for flank wear and surface roughness using the Taguchi method, and the effect levels of the cutting tools and cutting parameters were determined via analysis of variance. According to ANOVA results, for flank wear, the parameter having the most effect was the cutting speed, with an ratio of 56.811%, while for surface roughness it was the feed rate, with 95.827%. (C) 2020 The Author. Published by Elsevier B.V. Duzce University Research FundDuzce University [BAP-2016.22.01.435] This study was supported by the Duzce University Research Fund (BAP-2016.22.01.435). WOS:000556883600010 2-s2.0-85087078183

The features of magneto-abrasive machining of taps for metric thread cutting were investigated. The calculation method of integral intensity of the magneto-abrasive machining of the working surfaces of the taps by the quantitative values of normal and tangential components of moving speed of the quasi-stable volumes of the magneto-abrasive tool was developed. Based on the results of calculations, it was possible to predict the probable influence of the taps’ location in the working zone on the quality and efficiency of machining their working surfaces. The calculation method is relevant for taps of all diameters with a profile angle of 60°. The working surfaces of the tool would not be effectively machined if the location angle of taps to the plane of the working zone of the machine equals 20–60°. Depending on the expected major polishing or strengthening effect of magneto-abrasive machining, the taps are required to be located at an angle of 60–90° to the plane of the working zone of the machine.

The need for rare resources, such as tungsten or cobalt, combined with the high energy requirements to produce cutting materials, is forcing research and development to work out environmentally friendly alternatives. Natural rocks could be an alternative since they are available in large quantities worldwide, have a potentially suitable property profile, and do not require energy-intensive processes to make them usable as cutting materials. However, there are only a few studies on the usability and suitability of natural rocks as cutting materials for machining processes. Therefore, in this article, inserts made of natural rocks were ground and used in turning operations. First, the properties of various natural rocks were determined, as were the tool properties after grinding. Then, the tool load and wear during the machining process were recorded and evaluated to assess the potential applications of this alternative cutting material more accurately. It is therefore becoming apparent that flint and quartz are suitable for use as alternative cutting materials and should be further researched.

This paper proposes a method for determining the parameters of a single-lane hyperboloid as the initial tool surfaces of finger modular mills for large-modular gears and design dependences for determining the parameters of a hyperboloid in which the deviation of its curvilinear axial profile will be minimal from the involute curve. The influence of the gear module and the number of teeth and the theoretical deviations from the involute profile that can be achieved with this method of replacing the original tool surface are calculated and studied. Recommendations for design are given and the design of schemes of cutting and cutting part of a finger mill on the basis of a hyperboloid at their realization by non-grinding carbide plates of rectangular form is offered that considerably improves manufacturability of production of such mills and reduces their cost. The advantages and disadvantages of such tools, which are made on the basis of hyperboloid in comparison with the tools of standard designs, are determined., В данной работе предложена методика определения параметров однополосного гиперболоида в качестве исходных инструментальных поверхностей пальцевых модульных фрез предназначеных для обработки крупномодульных зубчатых колес и расчетные зависимости для определения параметров гиперболоида, при которых отклонение его криволинейного осевого профиля будет минимально от кривой эвольвенты, что важно при проектировании таких инструментов. Рассчитано и исследовано влияние модуля зубчатого колеса и числа зубов и теоретические отклонения от эвольвентного профиля, которые можно достичь при таком способе замены исходной инструментальной поверхности. Приведены рекомендации по проектированию и предложена конструкция схем резания и режущей части пальцевой фрезы на базе гиперболоида при их реализации неперетачиваемыми твердосплавными пластинами прямоугольной формы, что значительно улучшает технологичность изготовления таких фрез и снижает их стоимость. Определены преимущества и недостатки таких инструментов, которые выполнены на базе гиперболоида по сравнению с инструментами типовых конструкций., В даній роботі запропоновано методику визначення параметрів однополосного гіперболоїду в якості вихідних інструментальних поверхонь пальцевих модульних фрез призначених для обробки крупномодульних зубчастих коліс та розрахункові залежності для визначення параметрів гіперболоїду при яких відхилення його криволінійного осьового профілю буде мінімальне від кривої евольвенти, що є важливо при проектуванні таких інструментів. Розраховано та досліджено вплив модуля зубчастого колеса та числа зубів і теоретичні відхилення від евольвентного профілю, яких можна досягти при такому способі заміни вихідної інструментальної поверхні. Наведено рекомендації з проектування та запропоновано конструкцію схем різання та різальної частини пальцевої фрези на базі гіперболоїду при їх реалізації непереточуваними твердосплавними пластинами прямокутної форми, що значно покращує технологічність виготовлення таких фрез і знижує їх вартість. Визначені переваги та недоліки для таких інструментів, що виконані на базі гіперболоїду в порівнянні з інструментами типових конструкцій.

This paper features a comprehensive analysis of various multiscale selforganization processes that occur during cutting. A thorough study of entropy production during friction has uncovered several channels of its reduction that can be achieved by various selforganization processes. These processes are (1) self-organization during physical vapor deposition PVD coating deposition on the cutting tool substrates; (2) tribofilm formation caused by interactions with the environment during operation, which consist of the following compounds: thermal barriers; Magnéli phase tribo-oxides with metallic properties at elevated temperatures, tribo-oxides that transform into a liquid phase at operating temperatures, and mixed action tribo-oxides that serve as thermal barriers/lubricants, and (3) multiscale selforganization processes that occur on the surface of the tool during cutting, which include chip formation, the generation of adhesive layers, and the buildup edge formation. In-depth knowledge of these processes can be used to significantly increase the wear resistance of the coated cutting tools. This can be achieved by the application of the latest generation of complex adaptive surface-engineered systems represented by several state-of-the-art adaptive nano-multilayer PVD coatings, as well as high entropy alloy coatings (HEAC).

Orientador: Amauri Hassui Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica Resumo: Sabe-se que atualmente a competitividade das empresas é fator de sobrevivência. Assim, a busca por redução de custo é um constante desafio. Um aspecto dentro dos processos de fabricação que atua diretamente nesse tocante é o desenvolvimento de melhores ferramentas de corte. Este trabalho trata da reafiação de ferramentas de corte denominadas bedame, que possuem custo mais elevado que as demais ferramentas. O material usinado foi o ferro fundido nodular, que possui propriedades mecânicas características e consumir menor energia em sua fusão. Nos processos de usinagem são utilizadas as mesmas ferramentas para os ferros fundidos nodulares e cinzentos, porém o primeiro é um material dúctil, diferente do segundo que é frágil. Isso implica em um comportamento diferente na usinagem, mostrando que cabe neste caso uma melhor adequação das ferramentas de corte. Após a utilização de bedames novos, estes foram reafiados em quatro modelos diferentes. Posteriormente foram testados quatro tipos de revestimento PVD. Na sequência avaliou-se também a influência da velocidade de corte, avanço e concentração do fluido de corte. O critério adotado para a determinação do fim da vida dos bedames foi à qualidade da face usinada. Os ensaios foram feitos em sequência, sendo que o passo seguinte utilizava apenas os melhores resultados do passo anterior. Os resultados indicaram que bedames com ângulo de saída positivo, revestidos com AlTiN, usinando com menores velocidades de corte e avanço e com maior concentração de óleo no fluido de corte, apresentaram vida mais longa. Por outro lado, o mesmo bedame, só que revestido com TiCN e operando nas mesmas condições, apresentou a melhor relação custo benefício dentre os bedames reafiados. Concluiu-se assim que é viável economicamente a reafiação dos bedames Abstract: It is known nowadays that the companies' competitiveness is a survival factor. So, the search for cost reduction is a constant challenge. One aspect of the manufacturing processes that act directly in this aspect is the development of better cutting tools. This work is about cutting tools to part materials named parting tools that has higher costs than the other cutting tools. The machined material was the nodular cast iron that has specific mechanical characteristics and demands less energy in its melting. In the machining processes it is usually used the same cutting tools to machine nodular and grey cast iron, but the first is ductile different from the second that is fragile. This implies in a different machining behavior, showing that is possible in this case a better adequation of the cutting tools. After using the new parting tools, they were resharpened in four different models. After that were tried four different PVD coatings. In the sequence it was also evaluated the influence of the cutting speed, the feed and cutting fluid concentration. The criteria adopted to determine the end of the parting tool life was the quality of the machined surface. The tests were carried out in sequence in such a way that the next step used just the best results of the former step. The results indicated that parting tool with positive rake angle, coated with AlTiN, operating in lower cutting speeds and feeds and with higher cutting fluid concentration, presented longer tool life. On the other hand, the same parting tool, but coated with TiCN and operating at the same cutting conditions, presented a better cost benefit relation among the resharpened cutting tools. It can be concluded that is economically feasible the parting tools resharpening Mestrado Materiais e Processos de Fabricação Mestre em Engenharia Mecânica

Tool failure is one of the main causes of failure in CNC machine tool machining. The real-time online monitoring technology of CNC machine tool is studied, which is helpful to improve the efficiency of failure-free operation of CNC machine tool and reduce the probability of scrap and equipment failure due to tool failure. Here, the correlation between inverter input current and tool wear condition was studied first, based on which a new method about how to calculate line current on inverter input side was defined, according to definition of current virtual value. Then, a real-time monitoring system for online tool wear is designed and developed. The experimental results show that the system can reflect the tool wear condition and remind to change tool timely.

The development of approaches for the non-thermal sterilization of instruments is an urgent task to ensure the safety of meat industry products, where the use of hot water leads to the formation of condensates and a deterioration in the hygienic condition of the premises. In this study, an installation for sterilizing knives was created, which works by activating aqueous salt solutions with a glow discharge. The power consumption of the installation reactor is only 125–150 Wh. The temperature rise of the sterilizing agent used is about 1.1 ± 0.2 °C/min/L. The effectiveness of the installation for plasma-activation of aqueous solutions of chloride and sodium sulfate by glow discharge (PAW) in relation to the inactivation of microorganisms, including Staphylococcus aureus, Salmonella typhimurium, Pseudomonas gessardii and L. monocytogenes, on steel surfaces was evaluated. Samples of stainless steel (parts of knives) were used in two versions (new and artificially aged). Mono- and polyspecies bacterial biofilms were grown on the surface of the samples. The treatment was carried out by immersing samples of steel plates in plasma-activated aqueous solutions. It was found that the treatment of plates in a knife sterilizer for 1 min had an effective effect on the inhibition of all types of studied bacteria.

This study proposes a novel use of laser heating to increase the adhesion between coatings fabricated by low-temperature PVD and replaceable cemented carbide cutting inserts, thus extending the life of these cutting tools in the machining of difficult-to-machine materials. Our previous studies conducted on CVD coatings showed that these coatings had higher adhesion due to a much higher process temperature. However, taking into account the fact that PVD coatings have better technological properties (e.g., lower structure porosity, higher hardness, and better tribological properties) than CVD coatings, it is fully justified to investigate ways of improving the PVD coating adhesion to the substrate. In this study, replaceable cutting inserts with different hard coatings of titanium nitride were used. Laser heating was conducted with different power densities. The adhesion strength of the tested coatings was determined via vibration spectrum analysis. In addition, 2D surface imaging, scanning electron microscopy, and X-ray fluorescence spectrometry were employed to examine the coatings after laser heating. A significant increase in the adhesion of single-layer (TiN) and double-layer (TiCN + TiN) coatings to the cemented carbide substrate, together with increased tool life, was observed after heating the samples with 40% of the maximum laser power. The application of a multilayer coating containing thermal shock-sensitive (TiAlSi) N did not increase the tool life. This paper attempts to interpret the obtained results.

Orientador: Anselmo Eduardo Diniz Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica Resumo: O presente trabalho compara a usinabilidade de duas ligas de níquel similares existentes no mercado, utilizadas na fabricação de válvulas automotivas para motores de combustão interna. Procura-se explicar a usinabilidade destes materiais com base em suas propriedades mecânicas e térmicas. O aço válvula (VAT 36®) tem 36% de níquel em sua composição química e o aço (VAT 30®), similar ao aço (Ni30) da empresa Hitachi, tem 30 a 33% de níquel, o que representa um ganho de custo em sua fabricação. Para esta comparação foram utilizados ensaios de torneamento. As ferramentas ensaiadas eram negativas e positivas, a refrigeração das ferramentas utilizou pressão convencional e alta pressão 70 bar e a usinagem foi feita com duas velocidades de corte 70 e 85 m/min. Foram realizados ensaios de vida de ferramenta de corte, medidas as potências de corte e feitos testes de rugosidade das peças torneadas. A análise das ferramentas desgastadas apontou em todas as arestas, evidências de adesão, abrasão e attrition. Comparando-se as propriedades de ambos os aços válvula, verificou-se que o aço (VAT 30®) sendo 11% mais duro, 7% mais resistente à tração, conduzindo 28% menos calor e sendo 40% mais fácil de encruar, do que o aço (VAT 36®), supostamente deveria gerar menor vida das ferramentas. Mas os resultados mostram que a vida da ferramenta na usinagem do aço válvula (VAT 30®) foi maior que do (VAT 36®), com excessão do ensaio de usinagem com ferramenta positiva, alta pressão de refrigeração e velocidade de corte de 70 m/min. As causas deste resultado foram a menor ductilidade do aço (VAT 30®) (alongamento 10% menor) e o fato de ser menos abrasivo, com 22% menos carbonetos presentes, o que dificultou o surgimento do mecanismo de desgaste por adesão/attrition e de abrasão. O aço (VAT 30®) consumiu, em geral, maior potência de corte que o aço (VAT 36®), devido à sua maior resistência mecânica e maior taxa de encruamento. Os resultados mostram ainda, que o aço (VAT 30®), por alongar 10% menos, isto é, ter menor tendência de deformar-se plasticamente, tem menor tendência de gerar rugosidade na peça, do que o aço válvula (VAT 36®) Abstract: The present work compares the machinability of two similar nickel alloys used in the manufacture of automotive valves for internal combustion engines. The valve steel (VAT 36®) has 36% nickel in its chemical composition and steel (VAT 30®), similar to Hitachi (Ni30) steel, has 30 to 33% nickel, which represents a gain in cost in its manufacturing. Turning tests were used for this comparison. The tools tested were negative and positive, tool cooling used conventional pressure and high pressure 70 bar and the machining was done with two cutting speeds 70 and 85 m/min. Cutting tool life tests were performed, cutting power was measured and surface roughness tests were performed on turned parts. The analysis of worn tools indicated, evidences of adhesion, abrasion and attrition in all edges used in the experiments. Comparing the properties of both valve steels, it was found that steel (VAT 30®) being 11% harder, 7% more mechanically resistant, conducting 28% less heat and being 40% easier to hardening than the steel (VAT 36®), was supposed to lead to shorter tool life. But the results show that the tool lives in the machining of the valve steel (VAT 30®) was higher than (VAT 36®), except for the positive tool with high cooling pressure and cutting speed of 70 m/min. But steel (VAT 30®), which is 10% less ductile and 22% less abrasive, hindered the appearance of both adhesion/attrition and abrasion wear mechanism and consequently lead the tool to longer tool lives. The (VAT 30®) consumed, in general, less cutting power than the (VAT 36®) steel due to its higher mechanical strength and higher hardening rate. The results show that steel (VAT 30®), because it is less ductile and consequently presents lower tendency to deform plastically, has a lower tendency to generate roughness than the valve steel (VAT 36®) Doutorado Materiais e Processos de Fabricação Doutora em Engenharia Mecânica CNPQ 155588/2015-0

Carbon fiber-reinforced polymers (CFRPs) have very good mechanical properties, such as extremely high tensile strength/weight ratios, tensile modulus/weight ratios, and high strengths. CFRP composites need to be machined with a suitable cutting tool, otherwise, the machining quality may be reduced, and failures often occur. However, as a result of the high hardness and low thermal conductivity of CFRPs, the cutting tools used in the milling process of these materials complete their lifetime in a short cycle, due to especially abrasive wear and related failure mechanisms. As a result of tool wear, some problems, such as delamination, fiber breakage, uncut fiber and thermal damage, emerge in CFRP composite under working conditions. As one of the main failure mechanisms emerging in the milling of CFRPs, delamination is primarily affected by the cutting tool material and geometry, machining parameters, and the dynamic loads arising during the machining process. Dynamic loads can lead to the breakage and/or wear of cutting tools in the milling of difficult-to-machine CFRPs. The present research was carried out to understand the influence of different machining parameters on tool abrasion, and the work piece damage mechanisms during CFRP milling are experimentally investigated. For this purpose, cutting tests were carried out using a (Physical Vapor Deposition) PVD-coated single layer TiAlN and TiN carbide tool, and the abrasion behavior of the coated tool was investigated under dry machining. To understand the wear process, scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) was used. As a result of the experiments, it was determined that the hard and abrasive structure of the carbon fibers caused flank wear on TiAlN- and TiN-coated cutting tools. The best machining parameters in terms of the delamination damage of the CFRP composite were obtained at high cutting speeds and low feed rates. It was found that the higher wear values were observed at the TiAlN-coated tool, at the feed rate of 0.05 mm/tooth.

Ceramic roller is more reliable than metal roller. However, ceramic materials are difficult to process due to their high hardness and great brittleness. They are easy to crack and easy to damage cutting tools. To batch processing of ceramic roller blanks (CRBs), a special ceramic roller cutting equipment (SCRCE) is designed to deal with CRBs of different diameters and lengths. To avoid clamping damage to CRBs, the SCRCE adopts the new clamping mechanism. The blanks are orientated to double rotating shafts with V-type sleeves to reduce friction. Moreover, the SCRCE adopts a new ring-cut method. The ring-shape cutting is used. The cutting spindle and the blanks are revolving at the same time in cutting processing. The design and modelling of the special cutting equipment is also finished. To analysis the axial displacement of CRBs while cutting, the simulation model with ADAMS is built and the related characteristic is simulated. The test result shows that the new type cutting machine is suitable for ceramic roller blank cutting process.

Alloy Ti-6Al-4V is a frequently used material in aero space applications due the high strength and low weight. This material is however often considered as a difficult to machine alloy due to several material properties such as the inherent characteristics of high hot hardness and strength which is causing an increased deformation of the cutting tool during machining. The thermal properties also cause a low thermal diffusion from locally high temperatures in the cutting zone that allows for reaction to the tool material resulting in increased tool wear. Predicting the behavior of machining of this alloy is therefore essential when selecting machining tools or machining strategies. If the surface integrity is predicted, the influence of different machining parameters could be studied using Particle Finite Element (PFEM)-simulations. In this investigation the influence from cutting speed and feed during turning on the residual stresses has been measured using x-ray diffraction and compared to PFEM-simulations. The results showed that cutting speed and feed have great impact on the residual stress state. The measured cutting force showed a strong correlation especially to the cutting feed. The microstructure, observed in SEM, showed highly deformed grains at the surface from the impact of the turning operation and the full width half maximum from the XDR measurements distinguish a clear impact from different cutting speed and feed which differed most for the higher feed rate. The experimental measurements of the residual stresses and the PFEM simulations did however not correlate. The surface stresses as well as the sign of the residuals stresses differed which might be due to the material model used and the assumption of using a Coulomb friction model that might not represent the cutting conditions in the investigated case. © 2018 Elsevier B.V. All rights reserved.

Cemented carbide tools are often used for milling operations that cause high thermal and mechanical process loads, e.g. machining processes for titanium alloys. However, the disposal of those tools after one life cycle would significantly reduce their resource efficiency. Therefore, regrinding operations are crucial in order to recycle worn tools and ensure an economical as well as resource efficient manufacturing process. The main challenges during regrinding are the precise quantification of present defects and the subsequent determination of the grinding allowance. As it is, a worker performs both tasks using his individual estimations. Consequently, the estimated grinding allowance is often too low or too high. This either decreases the lifetime of the reground tools due to remaining defects or reduces the resource efficiency since more material than necessary is removed. This paper investigates the determination of the grinding allowance and the environmental impact of regrinding operations on the life cycle of the investigated tools. It is shown that about 12.5% percent of the worn tools are being unnecessarily disposed of. Furthermore, the resource efficiency of tools with small breakouts might be increased by 20% if the recommended allowance strategy is utilized. The tool wear of the grinding tools is also taken into consideration in order to further increase the resource efficiency of the whole life cycle, including milling tool and grinding wheel. The results show that small grain sizes and low grain concentrations are not suitable for efficient regrinding processes since higher wear and consequently higher geometrical inaccuracies of the reground tools occur.

Tool condition monitoring systems are essential in micromilling applications. A tool’s slenderness requires high-precision monitoring systems for online measurements. In most cases, tool health is indirectly estimated by processing and analyzing the cutting process parameters. In that sense, the main challenge lies in the proper selection of the process parameters and their processing techniques, so that a robust and accurate assessment of the tool’s health is obtained. This paper proposes a frequency- and time-frequency-based analysis of cutting force and vibration signals for estimating the tool condition of a high-speed micromilling process. Measurements obtained from different cutting conditions were utilized in the analysis. The results indicate variations in the dominant frequencies, which result from tool wear. Furthermore, it is important to note that the analysis results obtained from the two process signals provide more reliable results and improve the sensing bandwidth.

WC cemented carbides are used extensively as cutting and drilling tools in the cutter heads of the full face Tunneling Boring Machines (TBMs). This paper describes the effects of microstructural properties of selected cemented carbide grades, operating as cutting tools in dry and foam conditioned soil, towards abrasive wear resistance. The work was carried out with the purpose of identifying the most promising cemented carbide microstructural formulation against abrasive wear and of defining the possible changes induced on the wear mechanisms by conditioning agents. Microstructures of six commercial grades of cemented carbides with different Co content and WC grain size were characterized. The wear tests were carried out using a testing device simulating the working environment of TBM cutter heads both in dry and conditioned soil. According to all experimental findings, wear resistance of the investigated cemented carbides strongly decreases as the grain size and mean binder free path increase, regardless of the test conditions. Furthermore, the carbides distribution, hereinafter called Delaunay distance, plays a crucial role on wear behavior, having a linear relation with the specific volume loss. Moreover, the optimal microstructural features to promote wear resistance are here described. Finally, foam conditioning of soils was found to strongly influence the wear resistance, by reducing binder ploughing and WC microcracking.

Machining efficiency could be increased and chatter vibrations could be suppressed by employing irregular pitch angles onto milling cutters. Applying variable pitch cutters could improve machining stability by disrupting the regenerative chatter mechanism and reducing cutting forces due to decreased nonlinear dynamic chip thicknesses. Previous studies on variable pitch cutters have been mainly on investigating vibration suppression and dynamic modelling. There is a lack of efficient and practical variable pitch cutter design methods for practical industrial applications. An analytical method for designing milling cutters with alternating variable pitches has been proposed in this paper. In this method, a new variable, the generic sum of phase difference between the inner and outer waves, has been defined to model the machining dynamics and stability of the variable pitch cutter. The phase difference value has then been investigated to obtain its generic optimal solution to the stability limit considering different cutting conditions. Based on this, the analytical variable pitch cutter design method is derived. The experimental results have manifested that, compared with uniform pitch cutter, the variable pitch cutter, designed using the proposed method, was able to achieve 1) a critical stable axial depth of cut improvement of 126% under the desired spindle speed, 2) a cutting force reduction of 53%, 3) a decrease of 75% and 52% in Sq (the root mean square length of the scale limited surface) and Sz (the maximum height of the scale limited surface) of the machined surfaces respectively. These significant improvements approved the superiority and robustness of the proposed design method for chatter suppression and may promote the application of variable pitch cutter technologies.

In turning operations, the wear of cutting tools is inevitable. As workpieces produced with worn tools may fail to meet specifications, the machining industries focus on replacement policies that mitigate the risk of losses due to scrap. Several strategies, from empiric laws to more advanced statistical models, have been proposed in the literature. More recently, many monitoring systems based on Artificial Intelligence (AI) techniques have been developed. Due to the scope of different artificial intelligence approaches, having a holistic view of the state of the art on this subject is complex, in part due to a lack of recent comprehensive reviews. This literature review therefore presents 20 years of literature on this subject obtained following a Systematic Literature Review (SLR) methodology. This SLR aims to answer the following research question: “How is the AI used in the framework of monitoring/predicting the condition of tools in stable turning condition?” To answer this research question, the “Scopus” database was consulted in order to gather relevant publications published between 1 January 2000 and 1 January 2021. The systematic approach yielded 8426 articles among which 102 correspond to the inclusion and exclusion criteria which limit the application of AI to stable turning operation and online prediction. A bibliometric analysis performed on these articles highlighted the growing interest of this subject in the recent years. A more in-depth analysis of the articles is also presented, mainly focusing on six AI techniques that are highly represented in the literature: Artificial Neural Network (ANN), fuzzy logic, Support Vector Machine (SVM), Self-Organizing Map (SOM), Hidden Markov Model (HMM), and Convolutional Neural Network (CNN). For each technique, the trends in the inputs, pre-processing techniques, and outputs of the AI are presented. The trends highlight the early and continuous importance of ANN, and the emerging interest of CNN for tool condition monitoring. The lack of common benchmark database for evaluating models performance does not allow clear comparisons of technique performance.

Inconel 718 is the most popular nickel-based superalloy, extensively used in aerospace, automotive and energy industries owing to its extraordinary thermomechanical properties. It is also notoriously a difficult-to-cut material, due to its short tool life and low productivity in machining operations. Despite significant progress in cutting tool technologies, the machining of Inconel 718 is still considered a grand challenge. This paper provides a comprehensive review of recent advances in machining Inconel 718. The progress in cutting tools’ materials, coatings, geometries and surface texturing for machining Inconel 718 is reviewed. The investigation is focused on the most adopted tool materials for machining of Inconel 718, namely Cubic Boron Nitrides (CBNs), ceramics and coated carbides. The thermal conductivity of cutting tool materials has been identified as a major parameter of interest. Process control, based on sensor data for monitoring the machining of Inconel 718 alloy and detecting surface anomalies and tool wear are reviewed and discussed. This has been identified as the major step towards realising real-time control for machining safety critical Inconel 718 components. Recent advances in various processes, e.g. turning, milling and drilling for machining Inconel 718 are investigated and discussed. Recent studies related to machining additively manufactured Inconel 718 are also discussed and compared with the wrought alloy. Finally, the state of current research is established, and future research directions proposed.

Metal additive manufacturing (AM) has been one of the most useful processes in the manufacturing field. It has significant advantages in terms of the benefits of feature freedom and material waste reduction. These processes commonly use a heat source to fabricate a 3D shape through melting of a metal powder and subsequent solidification. The directed energy deposition method can stack the desired amount of material in the required location. This study addresses the thermal effects of a WC-Co cutting tool insert deposited by AM of titanium alloy powder in the turning process. First, the optimal deposition conditions were selected by conducting preliminary experiments. Second, titanium alloy powder was deposited on the turning insert under the selected conditions. Finally, verification evaluation was carried out in the turning process. The thermal effects of the turning insert with the titanium alloy were compared with an ordinary cutting tool insert. The average temperature of the cutting tool was reduced by 15% during operation.

Literally, hard machining describes machining of parts having hardness over 45 HRC. Besides its advantages like high metal removal rate, easiness of adapting to complex part geometries, possibility of dry cutting; this operation, which can substitute grinding in most cases, has some disadvantages. One of them is the significant increase of surface roughness due to tool wear even when the tool life limit is not exceeded. In this study, considering hard turning praxes, higher depths of cut (0.5 to 1.0 mm) were examined when dry turning AISI D2 cold work tool steel, through-hardened to 62 HRC. TiN coated mixed ceramic inserts (Al2O3 + TiCN) were employed in the operations. Relationship between surface roughness and cutting parameters (cutting speed, feed and depth of cut) was modeled and analyzed using a Box-Behnken response surface methodology (RSM) design. A linear model best described this relationship. Despite the higher depths of cuts, the surface roughness values achieved were comparable to those in grinding operations. Finally, the optimal values of cutting parameters for minimum surface roughness were predicted.

International audience; The recent increase in machining productivity is closely related to longer tool life and good surface quality. In the present study, an experimental technique is proposed to evaluate the performance of a cemented carbide inset during the machining of AISI D3 steel. The aim of this technique is to find a relationship between the vibratory state of the cutting tool and the corresponding wear during machining in order to detect the beginning of the transition period to excessive wear. A spectral indicator named spectral center of gravity, SCG, is proposed to highlight the three phases of tool wear using the spectra of the accelerations measured. Very promising results are obtained which can be used to underpin an industrial monitoring system capable of detecting the onset of transition to excessive wear and alerting the user of the end of the tool’s life. The purpose of this study is to review the vibration analysis techniques and to explore their contributions, advantages and drawbacks in monitoring of tool wear.

WOS: 000401074600007, Machining of Inconel 718 is a challenging process because of high hot strength and hardness, high reactivity with the tool materials and low thermal conductivity of Inconel 718 alloy. Although SiAION ceramics in the form of indexable inserts are utilized successfully in turning and milling operations of Inconel 718, application of solid SiAION milling cutters on high speed milling of superalloys is rare. In this study, SiAION ceramics were manufactured in the form of solid milling cutters and tested in high speed milling of Inconel 718 in order to investigate the wear mechanisms during machining process. The wear based on the severe adhesion of the work-piece to the tool flank face and repeated formation and removal of an Al and Ti-rich diffusion layer was observed at the flank faces of the tools, Scientific and Technological Research Council of Turkey (TUBITAK-TEYDEB) [1140148], The financial support of this study by The Scientific and Technological Research Council of Turkey (TUBITAK-TEYDEB) under the project number 1140148 is gratefully acknowledged.

A variety of cutting tool materials are used for the contact mode mechanical machining of components under extreme conditions of stress, temperature and/or corrosion, including operations such as drilling, milling turning and so on. These demanding conditions impose a seriously high strain rate (an order of magnitude higher than forming), and this limits the useful life of cutting tools, especially single-point cutting tools. Tungsten carbide is the most popularly used cutting tool material, and unfortunately its main ingredients of W and Co are at high risk in terms of material supply and are listed among critical raw materials (CRMs) for EU, for which sustainable use should be addressed. This paper highlights the evolution and the trend of use of CRMs) in cutting tools for mechanical machining through a timely review. The focus of this review and its motivation was driven by the four following themes: (i) the discussion of newly emerging hybrid machining processes offering performance enhancements and longevity in terms of tool life (laser and cryogenic incorporation); (ii) the development and synthesis of new CRM substitutes to minimise the use of tungsten; (iii) the improvement of the recycling of worn tools; and (iv) the accelerated use of modelling and simulation to design long-lasting tools in the Industry-4.0 framework, circular economy and cyber secure manufacturing. It may be noted that the scope of this paper is not to represent a completely exhaustive document concerning cutting tools for mechanical processing, but to raise awareness and pave the way for innovative thinking on the use of critical materials in mechanical processing tools with the aim of developing smart, timely control strategies and mitigation measures to suppress the use of CRMs.

CASTELLANO Los procesos de mecanizado por arranque de viruta tienen una gran importancia en la industria actual, puesto que permiten la fabricación de piezas de características muy diversas y de diferentes materiales. En este trabajo se analizará el proceso de fabricación de una pieza en un torno. Para ello, se tomará como ejemplo una pieza de ajedrez (la reina) y, tras fijar sus características geométricas y de material, se explicarán los pasos a seguir hasta la redacción de la hoja de proceso, que definirá los pasos y las condiciones del mecanizado. Para poder redactar este documento, antes habrá que decidir la secuencia de las operaciones de mecanizado, además de escoger las herramientas, parámetros de corte y la máquina-herramienta adecuadas. Por otro lado, dado que en la actualidad la mayoría de las máquinas funcionan mediante control numérico, se programará y explicará todo el proceso en un simulador de este tipo. EUSKERA Txirbil-harroketa bidezko mekanizazio prozesuek garrantzi handia dute gaur egungo industrian, hainbat material zein ezaugarri ezberdinetako piezen fabrikazioa ahalbidetzen baitute. Lan honetan tornu batean egindako pieza baten fabrikazio prozesua aztertuko da. Horretarako, xake pieza bat (erregina) hartuko da eredutzat eta, bere ezaugarri geometriko zein materialak finkatu ostean, prozesu orriaren idazketara arte jarraitu beharreko pausuak azalduko dira. Dokumentu honek mekanizazioaren pausuak eta baldintzak definituko ditu. Dokumentu hau idatzi ahal izateko, lehenik eta behin, tresna, mozketa parametro eta makina egokiak hautatzeaz gain, mekanizazio lanen sekuentziak erabaki beharko dira. Gainera, gaur egun makina gehienak kontrol numeriko bidez jarduten dutenez gero, prozesu osoa mota horretako simulagailu batean programatuko da. ENGLISH Machining processes are very important in today´s industry, as they are used for the manufacturing of parts with very diverse characteristics and made of different materials. This project will analyze the manufacturing process of a workpiece in a lathe machine. A chess piece (the queen) will be used as an example, and, after fixing its dimensions and material, the steps to write the process instruction sheet will be explained. This script will define the different phases and conditions of the machining process. Before writing this document, the sequence of the different operations has to be defined, as well as the adequate tools, cutting parameters and the machine tool. In addition to that, and as nowadays almost every machine tool works with a numerical control, the whole process will be programmed and explained in this kind of simulator.

Рассмотрена проблема совместного влияния параметров геометрической точности металлорежущих станков и режущих инструментов на точность обработки поверхностей деталей машин. Представлены основные зависимости для развития вариационного метода расчета точности металлорежущих станков в метод расчета точности металлорежущих систем., The work considers the problem of the joint influence of the geometric accuracy pa-rameters of metal-cutting machines and cutting tools on the accuracy of surface machining of machine parts. The main dependences for the development of the variational method for cal-culating the accuracy of metal-cutting machines into the method for calculating the accuracy of metal-cutting systems are presented.

The edge geometry of cutting tools directly influences the chip formation mechanism in micro-mechanical machining, where the edge radius and uncut chip thickness are in the same order of magnitude. An uncut chip thickness that is smaller than the cutting edge radius results in a large negative rake angle during machining, and built-up edge formation then affects the mechanics of the process. In this study, micro-scale orthogonal cutting tests on titanium alloy Ti6Al4V were conducted to investigate the influence of built-up edge formation on the machining forces and surface roughness. Cutting edges in these tests are engineered using wire EDM technique to have an edge radius of around 2 μm and clearance angles of 7° and 14°. It is observed that machining process inputs (uncut chip thickness, cutting speed, and clearance angle) affect the size of the built-up edge, which in turn affect the process outputs. It is observed that built-up edge formation protects the cutting edge from flank and crater wear under micro machining conditions and the influence of built-up edge on the surface roughness varies depending on the cutting speed and uncut chip thickness. Our findings also indicate a close relationship between the minimum uncut chip thickness and the mean roughness depth (Rz) of the machined surface. The minimum uncut chip thickness is found to be around 10% of the edge radius in the presence of built-up edge.

In this paper, an underwater laser cutting process for maintenance and replacement operations is presented and investigated regarding process robustness for the application in rough environments. A Yb:YAG laser is used with 4 kW laser power in an active cutting process with oxygen as cutting gas. For 10 mm thick constructional steel plates a process window is determined with the focus on robustness for distance interferences. The examined parameter sets include the nozzle clearance, focus positioning and cutting gas pressure adjustment, as they are significant factors of influence in underwater laser cutting. By adjusting the developed parameter sets, sheets with thicknesses up to 50 mm, as well as plates that are fixed to a concrete backing are cut. The used equipment, which completely consists of standard components, is presented along with its preparation for underwater operation.

For the development of a robot based laser cutting process of automotive 3D parts consisting of carbon fibre reinforced plastics (CFRP), investigations with a newly developed fibre guided nanosecond pulsed laser with an average power of P L = 1.5 kW were conducted. In order to investigate the best combination of quality and process time 2 different optical fibres were used, with diameters of d f = 400 μm and d f = 600 μm. The main differences between the two setups are the resulting focal diameter and the maximum available pulse energy up to E P = 80 mJ. In a first instance, a comparable investigation was performed with both fibres for a constant pulse overlap. For each fibre the minimum required line energy was investigated and cuts were performed, distributed over the complete parameter range of the laser source. The influences of the fibre diameter on the quality and efficiency of the cutting process are summarized and discussed.

Using conventional grinding wheels, self-excited vibrations are one of the most limiting factors in terms of productivity and process stability in cylindrical plunge grinding. Depending on the dynamic behavior of the workpiece and machine, workpiece vibration copy on the grinding wheel's surface, caused by uneven wear. This results in increasing waviness and, therefore, increasing workpiece vibration. In this context, an active vibration control, using a self-built magnetic actuator to influence the tool wear, is presented. The limits and possibilities of this influence are examined in this paper, i. e. the generation and reduction of waves on the grinding wheel. Furthermore, the prevention of chatter vibration and its robustness against parameter variation is analyzed and presented.

Due to the rising number of car variants, the production systems in automobile industry are driven by a strong demand for flexible production processes. In the production of thin-walled workpieces, forming and cutting processes stand in concurrence to each other. In many applications, cutting processes facilitate higher flexibility regarding possible workpiece geometries. However, the required productivity is demanding. In this paper, a multi-sectional milling tool is developed to reach the required cutting performance by minimizing secondary processing times. Tool geometry is optimized with statistical methods to enable a target oriented tool development and reduce iterative development steps in milling tool design processes. BMBF/02PN2187

Huge amount of CVD-diamond coated milling tools were used for machining of CFRP and CFRTP sheets and blocks in the airplane and automotive industries. Because of chipping and tooth-tip damage in the diamond coatings during those dry machining processes, the tools must be exchanged with new ones to preserve the geometric accuracy in practice. WC (Co) substrate in these used tools had to be recycled to lower the production cost; reliable ashing process was necessary to remove only the used diamond coatings without significant damages even to the tooth tip of substrate. Furthermore, fast-rate ashing became a key to shorten the leading time for exchange of milling and drilling tools. High density oxygen plasma ashing method with use of the hollow cathode device was proposed to remove the used diamond coating with the film thickness of 10 μm. Both the emissive-light optical spectroscopy and the Langmuir probe method were employed to make quantitative diagnosis on the generated oxygen plasmas. The average ion density increased up to more than 1x1017 m-3, higher than the conventional plasma states by one order. Activated oxygen atom had overwhelming population among the generated species in this high plasmas density. This high density oxygen flux was responsible for complete and fast-rate removal of CVD diamond coating; e.g. the average ashing rate turned to be more than 10 μm/hour. The short-shank, end-milling tools were employed to describe this ashing behavior with time. Corresponding to the variation of CO-peak intensity in the measured spectra by on-line spectroscopy, the diamond film thickness reduced monotonically with time up to 3.6 ks. The removal rate gradually decreased with time in the final stage. Fine tuning of oxygen plasma processing conditions was capable to reduce the damage depth of tool teeth tips down to 1 μm, significantly less than the standard tolerance of 5 μm.

Finite element (FE) models and the multi objective genetic algorithm (MOGA-II) have been applied for tool performance optimization while machining aluminum-based metal matrix composites. The developed and verified FE models are utilized to generate data for the full factorial design of experiment (DOE) plan. The FE models consist of a heterogenous workpiece, which assumes uniform distribution of reinforced particles according to size and volume fraction. Cutting forces, chip morphology, temperature contours, stress distributions in the workpiece and tool by altering cutting speed, feed rate, and reinforcement particle size can be estimated using developed FE models. The DOE data are then utilized to develop response surfaces using radial basis functions. To reduce computational time, these response surfaces are used as solver for optimization runs using MOGA-II. Tool performance has been optimized with regard to cutting temperatures and stresses while setting a limit on specific cutting energy. Optimal solutions are found with low cutting speed and moderate feed rates for each particle size metal matrix composite (MMC).

Cemented carbides are hard materials used for the fabrication of cutting tools. They consist of hard micron or sub-micron carbide grains held together in a matrix of a tough metallic binder such as cobalt. The understanding and control of cobalt characteristics are of crucial importance to improve the mechanical properties of WC-Co cemented carbide materials. Indeed, cobalt controls the toughness of the material and its properties seem to condition the durability of cemented carbides. At low temperature, pure cobalt is normally found in hcp structure, while above 426 degrees C (700 K) it changes to fcc crystalline structure. Remarkably, in cemented carbides, cobalt appears even at low temperature as fcc, otherwise as a mixture of fcc and hcp. It is unsure if these crystal structures are due to the presence of internal stresses or due to W and C soluted atoms. However, this paper demonstrates that cobalt in WC-10wt.%Co cemented carbide may show some characteristics of a glass transition at around 669 degrees C (942 K) in the 1 Hz frequency range, inducing a glassy state to cobalt, which is of great interest from a fundamental point of view, however challenging to control in materials technology.

The steel turning AISI 52100 has been gaining prominence in industry in recent years, as it allows machined parts to have better quality without the need for furthers processes. However, to ensure the final product quality, it is important that the turning for machining procedure is well planned and prepared, so that the cutting tools have their wear minimized in the process, while putting good productivity rates and zero occurrences of reworked parts. Thus, this article will study the quality of the machined surface in the turning process using interchangeable PCBN inserts. The aim is to identify the optimal combination of the input parameters that are cutting speed (Vc), feed (f) and machining depth (ap). The response measured is the roughness parameter Ra, under the influence of cutting fluid and tool wear.

Tool wear on the cutting edges of micro end mills is an important issue affecting process outputs such as tool deflections and surface roughness, especially when difficult-to-cut materials such as titanium alloys, stainless steel, etc. are machined at micro scale. An understanding of the interactions between tool wear, machining forces, tool deflections, and surface roughness is important in order to maintain component quality requirements. However, in literature, the number of studies concerning tool wear in micro end mills is limited. The goal of the paper is to better understand tool wear patterns (flank wear, edge rounding) of micro end mills and their relationship to machining parameters. In this study, first, the influence of tool wear on micro milling forces and surface roughness parameters is analyzed and favorable micro milling process parameters are identified. It is shown that, when machining with worn end mills, forces are affected by the tool wear patterns. Then, the influence of increased milling forces due to tool wear on tool deflections and tool breakage is studied using both experimental techniques and finite element analysis. The finite element model-based tool deflection and tool breakage predictions are validated through experiments. The results of this study can be used in process parameter selection in pocket micro milling operations and tool condition monitoring systems.

In analysis of machining processes, finite element analysis is widely used to predict forces, stress distributions, temperatures and chip formation. However, constitutive models are not always available and simulation of cutting processes with complex tool geometries can lead to extensive computation time. This article presents an approach to determine constitutive parameters of the Johnson-Cook's flow stress model by inverse modelling as well as a methodology to predict process forces and temperatures for complex three-dimensional tools using Oxley's machining theory. In the first part of this study, an analytically based computer code combined with a particle swarm optimization (PSO) algorithm is used to identify constitutive models for 70MnVS4 and an aluminium-alloyed ultra-high-carbon steel (UHC-steel) from orthogonal milling experiments. In the second part, Oxley's predictive machining theory is coupled with a multi-dexel based material removal model. Contact zone information (width of cut, undeformed chip thickness, rake angle and cutting speed) are calculated for incremental segments on the cutting edge and used as input parameters for force and temperature calculations. Subsequently, process forces are predicted for machining using the inverse determined constitutive models and compared to actual force measurements. The suggested methodology has advantages regarding the computation time compared to finite element analyses. BMBF/02PN2050

The work is aimed at improving the adaptive control efficiency for machining process on heavy machine tools. The integral complex of optimal control, which includes a heavy machine tool, systems of tools and tool management, adaptive control system with sets of measurement and diagnostic tools, the mathematical models of functioning of the technological system in terms of adaptive control developed. Ways to increase the efficiency and ecological compatibility of production and operation of machine tools in the manufacture of large-sized products for power purposes is studied in the paper.

Date of Conference: 11-12 June 2015 Conference Name: 15th CIRP Conference on Modelling of Machining Operations, CMMO 2015 As a result of increased use of CFRPs in the aerospace industry, the machining of CFRPs has been studied extensively. The majority of these studies consider drilling of CFRPs, since it is the most common process in the machining of structural parts used in aircraft. It has been shown that drilling process parameters and drill geometry significantly influence the quality of holes. In this study, a systematic approach has been used to compare the influence of drill geometry on process outputs such as drilling forces, torques and tool wear. Custom-made double point angle polycrystalline diamond (PCD) drills from the same manufacturer were used in the experiments. The advantage of this approach is that it eliminates the drill material and edge preparation effects on the experimental measurements, thus helps reveal the influence of drill geometry on the process outputs. The pros and cons of different drill designs are discussed and an appropriate design is identified for the drilling of thick CFRP laminate considered in this study.

© 2017, Allerton Press, Inc. The operation of a cutting wedge is studied in order to improve coating application on tools. A method of investigating the coating characteristics in plant conditions is outlined. The mechanisms of coating failure in cutting are established. The blunting of tools in the course of operation is analyzed. Coating application is optimized.

The machining of hard turning is carrying out on hardened steel in the range of 45 to 68 Rockwell hardness. It is substitute to traditional grinding process is a flexible, productive and successful machining process for hardened metals. Hence mainly used in various uses such as dies, moulds, tools, gears, cams, shafts, axles, bearings and forgings. The machining of hardened steel using superior tool materials such as coated carbide inserts, mixed ceramic inserts and cubic boron carbide nitride(CBN) have higher merits than traditional grinding such as high material removal rate, can produce good surface finish, reduced processing costs, ability to machine narrow walled sections and minimum environmental problems without using cutting fluid. Although the process is accomplish with small depth of cut and feed rates, evaluate to minimizing the machining time as high as 60% in hard turning process. In this paper, the machining of AISI D2 steel workpiece having 66 HRC hardness is carried out using coated carbide insert. The microstructure shows rolled grains of the steel along the direction of the material. The microstructure shows fine grains of cementite with the grain boundary chromium and other alloys and the presence of carbide, which increases strength and wearresistant. This paper discusses the importance of hard turning of AISI D2 steel. Investigations were carried out on conventional lathe using the prefixed cutting conditions. The graph shows the feed rate is the main impact with increasing feed rate, but reduces with larger cutting speed and rapidly increasing depth of cut. The responses studied in the investigation of surface roughness are studied in the investigation of surface roughness parameters (Ra,Rt and Rz) on responses are studied and presented in detail.

The aim of this work was to create a methodology for the development of wear-resistant coatings. These coatings were deposited on the working surfaces of carbide inserts which were used for rough re-profile machining of railway wheels-sets. The coatings were formed using a filtered cathodic vacuum arc deposition (FCVAD). An investigation into the effect of the FCVAD process parameters on the composition and properties of the coatings was undertaken. The experimental work replicated industrial application conditions in terms of cutting speed (40- 80 m/min), feed rates (0.8-1.2 mm/rev) and depth of cuts (4.0-8.0 mm). An increased tool life was achieved using carbide inserts with nanostructured multilayer composite coatings based on the Ti-TiN-TiAlCrN compound. The paper presents the results of carbide inserts with newly developed coatings for heavy duty machining of railway wheel-sets. The main coatings parameters i.e. microhardness, thickness, strength of adhesion of “coating-substrate” and surface morphology were studied. The nano-scale grain structure and thickness of sublayers for each coating component allowed achieving a balanced wear of rake and flank surfaces without micro/macro chipping of contact areas and cutting edge of the inserts. The results presented here show that the cutting tool life of the inserts with the new wear-resistance coatings exceeded commercial coated tools by a factor of more than two.

This paper is the result of research and operation modeling of the new systems for cooling of cutting tools based on thermoelectric module. A copper inlay with thermoelectric module on the back side was added to a standard turning tool for metal processing. For modeling and simulating the operation of thermoelectric module, finite element method was used as a method for successful solving the problems of inhomogeneous transient temperature field on the cutting tip of lathe knives. Developed mathematical model is implemented in the software package PAK-T through which numerical results are obtained. Experimental research was done in different conditions of thermoelectric module operation. Cooling of the hot module side was done by a heat exchanger based on fluid using automatic temperature regulator. After the calculation is done, numerical results are in good agreement with experimental. It can be concluded that developed mathematical model can be used successfully for modeling of cooling of cutting tools. [Projekat Ministarstva nauke Republike Srbije, br. TR32036]