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The paper provides an analysis of the impact of the values of cutting tool inclination strategies and angles measured in the parallel and perpendicular to feed direction, radial depth of cut and feedrate on the surface roughness. The workpiece was made of the AISI H13 steel, hardness 50 HRC, and was machined using a ball-nosed end mill with CBN edges. The research methodology involved experiments conducted based on the Taguchi orthogonal array, optimization of parameters with the use of Taguchi method and process modelling using neural networks. Thanks to the use of neural networks, the analyses were performed for various levels of machining efficiency, obtained as a result of different radial depths of cut and feedrates. In order to obtain mathematical models welldescribing strongly nonlinear impact of the cutting tool inclination strategies and angles, a separate neural network learned for each tool inclination strategy. The prediction of results was made using a set of neural networks. The analyses and experiments resulted in surfaces with very low Ra parameter of 0.16 mm and mathematical models with a good fit to the experimental data. Values of the cutting tool inclination angle that allow obtaining the surface of specific surface roughness were specified for various levels of machining performance. [ABSTRACT FROM AUTHOR]

This study introduces a new method for efficient and low-damage machining of Ti6Al4V: laser-assisted CBN belt grinding. The impact of laser power and grinding depth on the machining behavior of the material is investigated, the elemental distribution and chemical state of the ground surface are analyzed, and the removal mechanism of laser-assisted CBN belt grinding is described. The results show that increasing laser power will improve processing efficiency, enhance plastic material removal, and improve surface quality; the tangential grinding force is decreased by 63.5% and the normal grinding force is decreased by 72.6% at the maximum laser power; a large amount of Ti and N are present on the ground surface, and they are present in the form of TiN compounds. This study is a guide to the research on efficient and low-damage machining of hard-to-process materials like titanium alloys. [ABSTRACT FROM AUTHOR]

In the engineering world, the machining of advanced materials like titanium alloys, which is having their superior applications in a variety of domains, that is, bio-implants, biomedical, aerospace, and so on, has been a challenge for many decades to the researchers. The optimised surface topography for such alloys has been revealed as a function of various input parameters. In this study, an attempt has been made by conducting the experimental investigation on the surface integrity and the quality machined work surface in turning of titanium alloy, that is, Ti6Al4V through employing cryogenically treated and non-cryogenically processed CBN inserts. The surface quality and the integrity of processed titanium alloy work-surface have been investigated under the influence of various considered input factors. The design of experimentation was constructed for planning the experiments. The analysis of variance test has been attempted for the studied response, that is, surface roughness and the mathematical models for the studied surface roughness (with both CBN inserts; cryogenically and non-cryogenically treated) have also been developed. The attained optimised parametric conditions for surface roughness are; feed rate – 0.067 mm/rev, cutting speed – 63.852 m/min, and depth of cut – 0.526 mm; and feed rate – 0.066 mm/rev, cutting speed – 59.450 m/min, and depth of cut – 0.309 mm, for non-cryogenically and cryogenically treated CBN inserts, respectively. Artificial neural network (ANN)-based modelling has also been attempted to predict and analyse the dataset of experiments. There is a variation of 1.43% between ANN predicted data of NC CBN and NC CBN experimental data. Further, there is an error of 0.2% between ANN predicted data of Cryo-CBN and Cryo-CBN experimental data. The microstructure analysis of the turned titanium surface reflected the presence of few tearing and groove lines with both the CBN inserts employed. The scratches and bamboo lines have been due to the built-up edges produced in the inserts. [ABSTRACT FROM AUTHOR]

Hot machining is one method of machining easily hard materials. Heat is added to the cutting tool, resulting in a reduction in hardness and improved machining capabilities. During the hot turning process, the surface quality of the machined component improves. Cutting speeds, feed rates, and depth of cut for both CBN and TiAlN-coated tungesten carbide insert are optimised by trial and error. The effects of CBN and TiAlN inserts on hot turning and cold turning with minimal fluid application have been analysed in terms of power consumption, surface roughness, cutting force. [ABSTRACT FROM AUTHOR]

In this paper, the effect of minimum quantity lubrication (MQL) on tool wear in the hard turning of 100Cr6 ball bearing steel has been investigated and the results are compared to those obtained through dry and wet lubrication methods. The tools used in the study include CBN and nano-CBN tools. The nano-CBN tool is a new generation of CBN tools manufactured based on nanotechnology. No research has been conducted on the impact of this tool on machining processes. The ratio of NCBN tool flank wear land to the CBN tool flank wear land in dry, wet and MQL methods were 0.18, 0.23 and 0.28, respectively. The wear of CBN tool in turning with MQL was 2.8 times greater than the wear of nano-CBN tool in dry machining. In turning with nano-CBN tool, the height of the tool flank wear with MQL was reduced by 22% and 7% concerning wet and dry methods, respectively, while these values were 51% and 24%, respectively, for the CBN tool. The CBN tool wear depends on the lubrication method but the wear of the nano-CBN tool is almost independent of the lubrication method. [ABSTRACT FROM AUTHOR]

This study proposes a novel design of binders for polycrystalline cubic boron nitride (PcBN) cutting tool materials. Well-known binder phases TiC and TiN were combined with transitional metal nitrides ZrN, VN, and HfN. Performance screenings of longitudinal turning Inconel 718 and AISI 316 L highlighted the superior performance of PcBN materials with mixed TiC-ZrN and TiC-VN binders. These two systems were further sintered in a wider range of temperatures. XRD and STEM-XEDS analysis confirmed mutual dissolution of both TiC and ZrN, and TiC and VN, thus forming two types of solid solutions (Ti,Zr)(C,N) and (Ti,V)(C,N). Extended performance tests showed that tools with TiC-ZrN binder outperform reference PcBN with TiC binder by up to 20% when machining Inconel 718. When machining hardened Caldie tool steel, the performance of tools with TiC-ZrN and TiC-VN binders were 80–90% higher than the reference tools. [ABSTRACT FROM AUTHOR]

Nickel-based superalloys are known to be difficult to machine. These alloys are generally machined with cemented carbide tools under low productivity process conditions. Superhard polycrystalline cubic boron nitride (PcBN) tooling offers the possibility of increased production rates, however, a thorough understanding of the material performance and degradation is required before a transition from carbide tools occurs. This study investigated the performance and wear mechanism of three different PcBN tools with low (50 vol. %), medium (65 vol. %), and high (90 vol. %) cBN content, when turning AD730, a new Ni–Co-based superalloy. Due to the novelty of the material, little research has been done on its machinability with carbide and even less with PcBN tooling. The results showed the high-cBN grade was the best performer in terms of machining time. However, an undesirable wear morphology is generated, leading to excessively high cutting forces. Both the medium-cBN and low-cBN showed promise with stable rake and flank wear, but with notching as a drawback. Degradation analysis of medium-cBN grade revealed diffusional dissolution of cBN and formation of a reaction layer atop the cBN grains. The reaction layer, which acts as a diffusional barrier, consisted of three sub-layers: (1) Al 2 O 3 , (2) (Ti, Nb, Zr)N, and (3) (Ti, Cr, Nb, Zr)N. The low-cBN grade also showed a reaction layer; however, the smaller cBN grain size of this grade did not allow the layer to sufficiently stabilize. [ABSTRACT FROM AUTHOR]

This paper investigates the machinability of AISI 316L stainless steel without and with NMI treatment, when machined with three different PcBN tool grades: low cBN content (50% vol.), medium (65% vol.) and high (90% vol.). The NMI treatment consisted of resulfurized and Ca-treated steels with two different Si/Al ratio. The tool materials were evaluated in terms of tool life, showing the best performance for the medium cBN content grade. Results showed that the crater wear has a more significant effect on the tool performance than the standard wear criteria of maximum flank wear. The worn tools were examined using scanning electron microscopy (SEM), focused ion beam (FIB) and transmission electron microscopy (TEM). In most cases, the crater exhibited three distinct regions from the edge to the end of the contact zone: the plateau, middle crater, and the upper region. Plateau and crater region displayed tool protective layer (TPL), consisting mostly of Al, Si, Mg and Ca-oxides; and some dimples in the tool from preferential wear of cBN grains. In the upper region of the best performing material, a ~1.5 μm thick TPL of mostly MnCr 2 O 4 spinel was found, a result of the transfer of Mn- and Cr-rich oxide NMIs found in this material or oxidation of workpiece material, during the machining process. [ABSTRACT FROM AUTHOR]

This research work focuses on the experimental investigations conducted using uncoated cBN tool and (AlCrN) PVD Coated cBN tool for turning Inconel 718. Two different sets of experiments - one with uncoated cBN and another with coated cBN inserts were conducted considering three different levels of cutting speeds, feed rates and depth of cuts. The performance of the coated cBN over the uncoated inserts were evaluated and it was found that the AlCrN coated cBN inserts can produce 10-12% drop in the cutting force, 15% reduction in the flank wear and 10% reduction in the surface roughness. [ABSTRACT FROM AUTHOR]

Hard turning, a comparatively modern machining technology, can replace the conventional grinding process for finishing of parts made out of steel. Nowadays, industries prefer hard turning to grinding. This is due to some of the most distinctive features of hard turning over grinding, such as lower machining time and manufacturing cost, and the achievement of grinding equivalent quality characteristics on parts and machining can be possible in a dry environment, which eliminates the hazardous effect of cooling media used during machining on the environment and humans. However, in hard turning, machining parameters (cutting speed-vc, depth of cut-ap, and feed rate-f) are critical for achieving specified quality attributes and establishing a costeffective setup. The influence of machining parameters on workpiece surface roughness (Ra) and tool flank wear (VB) has been investigated in this research using the Taguchi Design of Experiment (DOE) approach, as well as signal to noise (S/N) ratio, and Analysis of variance (ANOVA) techniques. The experiments have been carried out on automotive gear made of SAEAISI 5120-compliant 20Mn5Cr5 alloyed hardened steel. The CBN cutting tool has been used for this research. [ABSTRACT FROM AUTHOR]

The present research investigates the performance of a TiN/PVD-coated CBN7050 tool when turning the gray cast iron EN-GJL-250. This is performed through carrying out two series of tests. The first are parametric tests aiming at evaluating the effect of each cutting parameter, i.e., the cutting speed, the feed rate and the depth of cut on the cutting forces, the cutting pressure, the surface roughness, and the cutting power. The second series of tests concern the modeling that would lead to predicting the output parameters. Both the analysis of variance and the response surface methodology are selected to develop the relationship between the input factors (Vc, f, and Doc) and the output parameters. The tests are carried out according to the Taguchi design (L27). The derived models are used to perform a multi-objective optimization of the cutting parameters through the application of the desirability function approach (DFA) for four objectives. Furthermore, the CBN7050 tool wear behavior was investigated during the machining of gray cast iron EN-GJL-250. Tool lives reached 7, 18, and 41.5 min when Vc was varied from 450, 600, to 750 m/min, respectively. Finally, a topographical analysis of the machined surface 3D roughness was carried out for different cutting parameters and led to displaying the texture of the surfaces. [ABSTRACT FROM AUTHOR]

Point grinding is an abrasive machining process that utilises miniature single layer superabrasive tools to remove material. The use of such small diameter tools offers advantages in the manufacturing of small or difficult to access complex 3D geometries, however, in their current state, these tools suffer from several critical challenges preventing their successful implementation. An investigation into the use of a typical commercially available point grinding tool for machining of hardened steel components has been carried out, with the aim of identifying the critical process challenges. The requirement for high rotational speeds, high tool deflection, variation in grit protrusion heights and bond layer thickness, accelerated tool wear, increased sensitivity to runout, zero cutting speed at tooltip and high tool loading have been identified as the main issues affecting the point grinding process. It is crucial that these challenges are correctly understood to facilitate future tool development. [ABSTRACT FROM AUTHOR]

In the current scenario, machinability of the super alloys is of greater importance in an aircraft turbine engine and land-based turbine applications owing to its superior properties. However, the machinability of these alloys is found to be poor owing to its inherent properties. Hence, a predictive model has been developed based on DEFORM 3D to forecast the machining attributes such as cutting force and insert's cutting edge temperature in turning of Nimonic C263 super alloy. The dry turning trials on Nimonic C263 material were carried out based on L27 orthogonal array using CBN insert. Linear regression models were developed to predict the machining attributes. Further, multi response optimization was carried out based on desirability approach for optimizing the machining attributes. The validation test was carried out for optimal parameter values such as cutting speed: 117 m/min, feed rate: 0.055 mm/rev and depth of cut: 0.25 mm. The minimum cutting force of 304N and insert's cutting edge temperature of 468 °C were obtained at optimum level of parameters. The predicted values by FEA and linear regression model were compared with experimental results and found to be closer with minimum percentage error. The minimum percentage error obtained by FEA and linear regression model for the machining attributes (cutting force, temperature) as compared with experimental values were (0.32%, 0.23%) and (2.34%, 1.63%) respectively. [ABSTRACT FROM AUTHOR]

Surface grinding is a widely used machining process for finishing of materials. Industry is looking for materials and techniques which are more productive as well as environment friendly. Researchers have worked upon various aspects to improve the overall performance of surface grinding in context of environmental and economic issues. But no comprehensive review on surface grinding, which covers all technological issues related to the process, including modelling and simulation, has been reported yet. This review is on research and technological advancements in surface grinding. It discusses critical findings pertaining to these advancements and gives recommendations related to surface grinding. [ABSTRACT FROM AUTHOR]

Despite excellent mechanical and physical features of titanium metal matrix composite (Ti-MMC), hard and abrasive ceramic particles within the matrix structure, as well as high price, may lead to severe difficulties on machining and machinability of Ti-MMCs. Review of literature denotes that only limited studies are available on machining Ti-MMCs with commercial cutting tools under various cutting conditions and cutting tools/inserts. Furthermore, limited studies are available on machinability attributes of Ti-MMC under various cutting conditions used. Therefore, to remedy the lack of knowledge observed, this work intends to report turning Ti-MMCs with carbide, and cubic boron nitride (CBN) inserts under various cutting conditions. The mean values of surface roughness (Ra) and directional cutting forces, as well as flank wear (VB) were studied as the machinability attributes. The microstructural evaluations were conducted to discover the wear modes. Furthermore, the statistical tools were used to present the factors governing machining attributes studied. Adhesion, abrasion, and oxidation were observed as the principle wear modes on the flank sides of the tested inserts. According to experimental results and statistical analysis, the Ra and VB could be controlled by cutting parameters only when CBN inserts were used. Despite the inset used, factors governing both responses were not identical. Although average cutting forces were directly affected by cutting parameters used, however, the relatively low correlation of determination (R2) of directional cutting forces can be attributed to effects of cutting speed, elevated temperature in the cutting zone as well as rapid tool wear which are all correlated to others. [ABSTRACT FROM AUTHOR]

Since the machinability data on grade 3 austempered ductile iron is scarce, this experimental work mainly focuses on the impact of machining parameters on cutting force and surface roughness while turning the above work material with cubic boron nitride and tungsten carbide inserts. Parameters like depth of cut, cutting speed and feed were considered in this study when analyzing the machinability of austempered ductile iron. Austempered ductile iron was turned with CBN and coated WC inserts. The response surface methodology was utilized to design the experiments and optimize the cutting parameters for the work material by each of the above inserts. The cubic boron nitride insert performs well as compared to the coated tungsten carbide for turning the austempered ductile iron and it has been concluded by taking lower force and higher surface finish in to consideration. The optimum parameters for turning austempered ductile iron with the cubic boron nitride insert is as follows: 174 meter/minute cutting speed, 0.102 millimeter/revolution feed and depth of cut of 0.5 millimeter. [ABSTRACT FROM PUBLISHER]

Metal matrix composites are the desired materials in aerospace and automotive industries since they possess high specific strength. However addition of reinforcement to the matrix material brings the adverse effects of high wear rate of tool materials used in their machining. The current study addresses the issues of wear and performance of superhard tools when high speed machining cast Al-Si alloy reinforced with particulate SiC (20% vol.). A wide range of developed superhard materials was compared to the commercial PCD tools. Nano grain sized wBN-cBN, binderless cBN; B 6 O-cBN, nano-diamond with WC binder; diamond/MAX-phase; and diamond/SiC tool materials were employed. Use of nano-diamond/WC and diamond/MAX-phase composites resulted in their rapid deterioration due to primarily adhesive pluck-out of diamond and binder phase. Diamond/SiC material exhibited slightly lower performance than the PCD, with the primary wear being the abrasive on the SiC binder phase. Machining with cBN-based tooling at lower speed lead to formation of stable build-up layer, frequently accompanied by severe seizure of tool and workpiece material. However at speed of 400 m/min the absence of such build-up layer caused rapid tool wear. Presence of chemical and diffusional wear mechanisms for diamond tooling has been confirmed through scanning and transmission electron microscopy. Archard-type model of abrasive tool wear was developed for modelling of tool deterioration for all studied tool materials. [ABSTRACT FROM AUTHOR]

The high-performance machining of difficult-to-cut alloys requires the development and optimization of high-performance tools, able to withstand the thermo-mechanical tool load without compromising the surface quality of produced components. In this context, the machinability of titanium aluminides still represents a demanding challenge. In this paper, the performance of cubic boron nitride (CBN) and polycrystalline diamond (PCD) cutting inserts is compared to that of uncoated and coated carbide tools. Longitudinal external turning tests were performed on a Ti-43.5Al-4Nb-1Mo-0.1B (TNM) at.% cast and hot isostatically pressed (HIPed) γ-TiAl alloy, by using a conventional lubrication supply. In addition, PCD tools were also applied under cryogenic cooling with liquid nitrogen. Results proved that PCD cutting tools have the potential to improve the machining productivity of titanium aluminides, due to their high hardness and excellent thermal conductivity. A noteworthy further increase of tool life was possible by using PCD cutting inserts under cryogenic cooling conditions. [ABSTRACT FROM AUTHOR]

In grinding many qualitative models for chip formation have been developed so far, which divide different phases of chip formation. A newly developed experimental single grain scratching method is presented, which enables to observe the chip formation in situ by means of a high speed video camera. Hence, it was possible to detect the transition of the chip formation phases for the first time and to determine specific grain engagement depths at the transition points. Based on experimental investigations using CBN grains and workpieces made of hardened steel 100Cr6 (AISI 52100) the influence of the 3D grain shape on the chip formation was analysed on the basis of characteristic values. Finally, a quantitative chip formation model was derived, which takes account of the 3D grain shape as well as the cutting speed and the status of lubrication. Although the influencing quantity of the different grain shape characteristic differs, it has to be stated that the grain shape in direction of motion as well as in transversal direction has significant influence on the chip formation in grinding. [ABSTRACT FROM AUTHOR]

This paper presents an experimental evaluation of the performance of cubic boron nitride (CBN) tools in the machining of high-chromium white cast iron. Two types of CBN tool materials were evaluated in the tests, including polycrystalline cubic boron nitride (pCBN) and binder-less crystalline cubic boron nitride (bCBN). Performance in terms of the levels of cutting forces, tool wear, surface roughness and process stability was evaluated during and after cutting tests. The work materials used in the cutting tests included two groups with chemical compositions of two levels of carbon silicon (lower C-Si and higher C-Si) in as-cast and hardened states, respectively. Test results indicate that the cutting tool materials clearly exhibited different behaviour in the machining of high-chromium white cast iron. The pCBN tools demonstrated lower tool wear rates than the bCBN tools but had higher roughness levels on the workpiece surfaces. The cutting tools also behaved differently according to the different levels of C-Si content and heat treatment of the work materials. In addition, the study reveals the mechanism of the interactions between CBN tools and high-chromium white cast iron under a range of machining parameters. [ABSTRACT FROM AUTHOR]

Abstract: The present work concerns an experimental study of hard turning with CBN tool of AISI 52100 bearing steel, hardened at 64 HRC. The main objectives are firstly focused on delimiting the hard turning domain and investigating tool wear and forces behaviour evolution versus variations of workpiece hardness and cutting speed. Secondly, the relationship between cutting parameters (cutting speed, feed rate and depth of cut) and machining output variables (surface roughness, cutting forces) through the response surface methodology (RSM) are analysed and modeled. The combined effects of the cutting parameters on machining output variables are investigated while employing the analysis of variance (ANOVA). The quadratic model of RSM associated with response optimization technique and composite desirability was used to find optimum values of machining parameters with respect to objectives (surface roughness and cutting force values). Results show how much surface roughness is mainly influenced by feed rate and cutting speed. Also, it is underlined that the thrust force is the highest of cutting force components, and it is highly sensitive to workpiece hardness, negative rake angle and tool wear evolution. Finally, the depth of cut exhibits maximum influence on cutting forces as compared to the feed rate and cutting speed. [Copyright &y& Elsevier]

The study deals with the machinability properties of austempered ductile iron using cubic boron nitride cutting tools. To emphasize the role of the austempering process, ductile iron specimens were first austenitized in salt bath at 900°C for 60 min, after which they were quenched in a salt bath at 250°C and 325°C for 60 min. Machining tests were carried out at various cutting speeds under the constant depth of cut and the feed rate. Tool performance was evaluated based on the workpiece surface roughness and flank wear. The influence of the austempering temperature and cutting speed on the chip form was also studied. The results point out that the lower austempering temperature results in the increase in the cutting forces, while better surface roughness is attained. [ABSTRACT FROM AUTHOR]

In this study, investigations were carried out to evaluate the characteristics of ultrasonic vibration-assisted cutting of tungsten carbide material using a CNC lathe with CBN tool inserts. The cutting forces were measured using a three-component dynamometer, and the machined workpiece surfaces and chip formation were examined using a SEM. The experimental results showed that the radial force F x was much larger than the tangential force F z and axial force F y . The SEM observations on the machined workpiece surfaces and chip formation indicated that the critical condition for ductile mode cutting of tungsten carbide was mainly the maximum undeformed chip thickness when the tool cutting edge radius was fixed, that is, the ductile mode cutting can be achieved when the maximum undeformed chip thickness was smaller than a critical value. Corresponding to the chip formation mode (ductile or brittle), three types of the machined workpiece surfaces were obtained: fracture free surface, semi-fractured surface and fractured surface. It was also found that the cutting speed has no significant effect on the ductile chip formation mode. [ABSTRACT FROM AUTHOR]

Direct machining steel parts at a hardened state, known as hard turning, offers a number of potential benefits over traditional grinding in some applications. In addition, hard turning has several unique process characteristics, e.g., segmented chip formation and microstructural alterations at the machined surfaces, fundamentally different from conventional turning. Hard turning is, therefore, of a great interest to both the manufacturing industry and research community. Development of superhard materials such as polycrystalline cubic boron nitride (known as CBN) has been a key to enabling hard turning technology. A significant pool of CBN tool wear studies has been surveyed, in an attempt to achieve better processing and tooling applications, and discussed from the tool wear pattern and mechanism perspectives. Although various tool wear mechanisms, or a combination of several, coexist and dominate in CBN turning of hardened steels, it has been suggested that abrasion, adhesion (possibly complicated by tribochemical interactions), and diffusion may primarily govern the CBN tool wear in hard turning. Further, wear rate modeling including one approach developed in a recent study, on both crater and flank wear, is discussed as well. In conclusion, a summary of the CBN tool wear survey and the future work are outlined. [ABSTRACT FROM AUTHOR]

Advanced materials, such as high abrasion resistant cast iron, have great applications for abrasive and erosive environments. Since the amount and the hardness of the microstructural carbides constituents in this material is extremely high, the abrasion-resistance cast iron is generally difficult to be machined with traditional cemented carbide tool. The hard and abrasive particles in this material can remarkably shorten the cutting tool life through abrasion of tool face and deterioration of cutting edge. In this article, Cubic Boron Nitride (CBN) cutting tool has been used to machine a novel-abrasion-resistance (N-AR) cast iron. The performances of CBN tool under different lubrication conditions were evaluated in view of tool wear, cutting force, and surface roughness (Rz). Further more, the wear rate of CBN tool under different machining condition and the mechanism of the CBN tool in machining of this type of work materials has also been investigated. [ABSTRACT FROM AUTHOR]

Abstract: Recent improvements in the machine tools technology (specially the stiffness and positioning accuracy) as well as the advent of the cubic boron nitride (CBN) ceramic cutting tools made the finishing operations for machining hardened steel parts possible, using tools with defined cutting geometry in substitution to the traditional grinding operations. The advantages presented by the hard turning are sufficiently attractive for many plants, however these are still reluctant to adopt and substitute a well known and dominated process (grinding) for other one not totally understood. Aiming to expand the knowledge of the processing effects of hard turning on the finishing of the machined workpiece, as well as the effects on the tool wear life. Series of experiments with seven different types of CBN inserts had been carried out using inserts with wiper geometry, coated with TiAlN and TiN as well as with no coated ones. The cutting parameters had been specified in such a form to cover the entire field recommended by tool suppliers. The machined part was an axle of DIN 100Cr6 steel tempered to 62 HRc. All the machining operations were carried out at a Mazak-Quick-Turn using an tool holder DCLNR-164D with insert geometry ISO CNGA120408SO1020 with edge with T preparation with 0.102mm×20°. The tool wear control was carried out using an optic microscope Zollern Saturn and a roughness profiler Hommelwerk T8000. Following parameters were parameters were determined: VB MAX , R a, material removal rate and the tool life determined by the Taylor''s equation obtained for theoretically ideal cutting conditions. Preliminary analyses of the results compares with the literature indicating that they are significant. [Copyright &y& Elsevier]

In precision machining, due to the recent developments in cutting tools, machine tool structural rigidity and improved CNC controllers, hard turning is an emerging process as an alternative to some of the grinding processes by providing reductions in costs and cycle-times. In industrial environments, hard turning is established for geometry features of parts with low to medium requirements on part quality. Better understanding of cutting forces, stresses and temperature fields, temperature gradients created during the machining are very critical for achieving highest quality products and high productivity in feasible cycle times. To enlarge the capability profile of the hard turning process, this paper introduces prediction models of mechanical and thermal loads during turning of 51CrV4 with hardness of 68 HRC by a CBN tool. The shear flow stress, shear and friction angles are determined from the orthogonal cutting tests. Cutting force coefficients are determined from orthogonal to oblique transformations. Cutting forces, temperature field for the chip and tool are predicted and compared with experimental measurements. The experimental temperature measurements are conducted by the advanced hardware device FIRE-1 (Fiberoptic Ratio Pyrometer). [ABSTRACT FROM AUTHOR]

Abstract: In the paper authors described a method of CBN grinding wheel cutting ability evaluation and research results achieved with this method during grinding process. Research results, which allowed for verification of the method (e.g. measurements of grinding force components, surface roughness and waviness parameters and stress level in surface layer) were also presented. [Copyright &y& Elsevier]

In this experimental study, three SiC/Al metal matrix composites (MMCs) with SiC particles of 30, 45 and 110μm in mean sizes were produced using a melt stirring-squeeze casting route. Machining tests were carried out on the MMCs using cubic boron nitride (CBN) cutting tools at various cutting speeds under a constant feed rate and depth of cut. The effect of reinforcement particulate sizes and cutting speeds on tool wear was investigated. Furthermore, surface roughness measurements were also carried out on the machined surfaces. The results showed that tool wear was mainly dominated by flank wear and strongly influenced by reinforcement particulate size. The MMC containing SiC particles of 110μm proved to be unsuitable for the machining operation using CBN cutting tools due to the heavy fracture of the cutting edge and nose. In the composites reinforced with SiC particles of 30 and 45μm, 150m/min cutting speeds led to the lowest tool flank wear values while 100 and 200m/min cutting speeds resulted in higher tool flank wear values. [Copyright &y& Elsevier]

Wear behavior of cubic boron nitride (CBN) cutting tool when cutting P20 tool steel was investigated. Oblique cutting tests were performed on a CNC lathe using five speeds, namely, 240, 600 and 1000 m min−1. The CBN cutting tools were found to be superior to tungsten carbide (WC) tools. Fourfold increase in productivity and significant reduction in chipping and cratering was achieved for CBN as compared to WC. Wear, as the width of the wear land (VB), was monitored at selected time intervals; furthermore, topography of worn surfaces was performed, using a profilometer. Wear characterization of the rake and the flank surfaces as well as of the collected chips was conducted using a scanning electron microscopy (SEM), backscattered electron imaging and energy depressive X-ray (EDX). It was found that deformation in the chips occurs by localized shear deformation and the dominant wear mechanism at all speeds used was identified to be diffusive wear. At a 1000 m min−1 cutting speed, a secondary wear mechanism was identified, which is melt wear, i.e., formation of low melting point Cr and Mn compounds with the tool material and the subsequent ejection from the cutting zone. [Copyright &y& Elsevier]

In precision hard turning, tool flank wear is one of the major factors contributing to the geometric error and thermal damage in a machined workpiece. Tool wear not only directly reduces the part geometry accuracy but also increases the cutting forces drastically. The change in cutting forces causes instability in the tool motion, and in turn, more inaccuracy. There are demands for reliably monitoring the progress of tool wear during a machining process to provide information for both correction of geometric errors and to guarantee the surface integrity of the workpiece. A new method for tool wear monitoring in precision hard turning is presented in this paper. The flank wear of a CBN tool is monitored by feature parameters extracted from the measured passive force, by the use of a force dynamometer. The feature parameters include the passive force level, the frequency energy and the accumulated cutting time. An ANN model was used to integrate these feature parameters in order to obtain more reliable and robust flank wear monitoring. Finally, the results from validation tests indicate that the developed monitoring system is robust and consistent for tool wear monitoring in precision hard turning. [ABSTRACT FROM AUTHOR]

In this study, experiments are carried out to evaluate the characteristics of high speed cutting of tungsten carbide material using a Makino V55 high speed machine tool with cubic boron nitride (CBN) tool inserts. The cutting forces were measured using a three-component dynamometer, the surface roughness of the machined workpiece was measured using a Mitutoyo SURFTEST 301, and the machined workpiece surfaces and the chip formation were examined using a scanning electron microscope (SEM). Experimental results indicate that the radial force Fx is much larger than the tangential force Fz and the axial force Fy. Two types of surfaces of the machined workpiece are achieved: ductile cutting surface and fracture surface. Continuous chips and discontinuous chips are formed under different cutting conditions. Depth of cut and feed rate almost have no significant effect on the surface roughness of the machined workpiece. The SEM observations on the machined workpiece surfaces and chip formation indicate that the ductile mode cutting is mainly determined by the undeformed chip thickness when the tool cutting edge radius is fixed. Ductile cutting can be achieved when the undeformed chip thickness is less than a critical value. [Copyright &y& Elsevier]

This technical note looks at several attempts to machine parts coated with Ni5Al thermal spray. This coating is used in the overhaul and repair of gas turbine components. Machining the thermal sprays to achieve the dimensional tolerances and surface finish is needed. Turning tests were performed with small carbide inserts and with CBN. A study was made of tool performance and cutting process. In this way, tool life, wear mechanism, chip formation process, and actual roughness of turned parts were analyzed. In addition to the good performance of CBN inserts, some disadvantages of using coolant with CBN tools were detected and analyzed. [ABSTRACT FROM AUTHOR]

This article describes issues related to the machining of parts made of sintered nickel-cobalt alloy. Longitudinal turning with a CBN (cubic boron nitride) tool was analyzed. The results of experiments showed the influence of cutting parameters in the field of finishing machining on the values of cutting forces and specific cutting force, taking into account the wear of the cutting edge. Measurements and analysis of the topography and roughness parameters of the machined surface, as well as the cutting tool wear, were presented. The microscopic examination showed that the average grain size of the sintered nickel-cobalt alloy was 3.22 ± 0.1 (μm). The presence of the hardening state variability of the material during machining, as well as the value of the cutting force fluctuation as a function of the tool wear VB, were stated. The specific cutting force values increased to a small degree for the tool wear in the range of VB = 0–0.2 mm, and reached similar values in the range kc = 5500–7500 N/mm2. The specific cutting force values increased significantly for wear VB > 0.2 mm and were characterized by a large variability. The occurring phenomena were analyzed and several explanations were proposed. A recommendation was developed for the machining of parts made of sintered nickel-cobalt alloy. The Taguchi method was used in the experiment methodology. [ABSTRACT FROM AUTHOR]