Search

Surface roughness is one of the main bases for measuring the surface quality of machined parts. A large amount of training data can effectively improve model prediction accuracy. However, obtaining a large and complete surface roughness sample dataset during the ultra-precision machining process is a challenging task. In this article, a novel virtual sample generation scheme (PSOVSGBLS) for surface roughness is designed to address the small sample problem in ultra-precision machining, which utilizes a particle swarm optimization algorithm combined with a broad learning system to generate virtual samples, enriching the diversity of samples by filling the information gaps between the original small samples. Finally, a set of ultra-precision micro-groove cutting experiments was carried out to verify the feasibility of the proposed virtual sample generation scheme, and the results show that the prediction error of the surface roughness prediction model was significantly reduced after adding virtual samples. [ABSTRACT FROM AUTHOR]

When machining high-speed steels (HSS) with micro-wire electrical discharge machining (micro-WEDM), high surface quality is achieved as standard. The value of the roughness parameter Ra is less than 0.2 μm. However, the problem is the performance of the electroerosion process (MRR), which is low. This problem is related to the mechanical and physical properties of the HSS in combination with the setting of the main technological parameters (MTP). The proposed solution to eliminate this problem relies on the selection of proper procedures for the determination of optimization criteria in relation to Ra and MTP, with the inclusion of properties of the machined material. The solution consisted in the identification of four significant physical (ρ, κ) and mechanical (Rm, HRC) indicators of HSS properties, on the basis of which a suitable combination of the process output parameters Ra and MRR can be determined through established mathematical regression models using simulation and optimization. In the next step, the proper values of the MTP output process parameter settings, which correspond to the optimized output parameters Ra and MRR during machining of HSS by micro-WEDM technology, were then obtained by the same approach. [ABSTRACT FROM AUTHOR]

A coating can be a deciding factor for machining performance of a tool by improving its tool life and wear resistance. Additionally, a variety of elements, including coating thickness, composition ratio, layer sequencing in multilayer coatings, and deposition process, affect the coating's performance. In this study, the properties of single-layer AlTiCrN and AlTiN coatings deposited using PVD high-power impulse magnetron sputtering (HiPIMS) and scalable pulse power plasma (S3p) and multilayer TiN/TiAlN- and AlTiN/TiAlN-coated carbide tools deposited using PVD cathodic arc evaporation (CAE) were investigated. Initially, the coatings were characterized for physical properties. Moreover, the performance of these coatings for dry machining of DSS2205 steel are described with respect to tool wear and tool life. It was observed that the AlTiCrN coating deposited by the HiPIMS technique exhibited excellent properties, including low surface roughness 0.19 µm, coefficient of friction 0.35 µm, higher adhesion strength 110 N, and maximum operating temperature 1150 °C, followed by the S3p AlTiN coating with surface roughness 0.21 µm, adhesion strength 107 N, coefficient of friction 0.34 µm, and 850 °C maximum operating temperature. The TiN/TiAlN coating exhibited poor properties among all the tools used. Machining performance confirmed the excellent results obtained through characterization for the AlTICrN coating during dry machining of the DSS2205. [ABSTRACT FROM AUTHOR]

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]

The machining of Ti-6Al-4V alloys is challenging due to their high strength, poor thermal conductivity, and high chemical reactivity. When used in traditional machining, cryogenic coolants can reduce tool wear, thus extending tool life, improving surface finish, and requiring less power with reduced environmental effects. In this context, this study aimed to perform a machinability analysis of the surface roughness, power consumption, tool wear, and specific energy consumption of a Ti-6Al-4V titanium alloy and to comprehend the performance of dry and cryogenic machining in turning operations. A comprehensive analysis of tool wear and specific cutting energy (SCE) under dry and cryogenic machining was conducted. It was found that the machining time under a cryogenic environment was increased by 83% and 39% at 80 and 90 m/min compared to a cutting speed at 100 m/min. The higher cutting speed (100 m/min) in cryogenic environments produced an improved surface finish. Compared to dry machining, the cooling effect of liquid CO2 helped dissipate heat and reduce thermal damage, improving surface finish. The findings revealed that in dry conditions, approximately 5.55%, 26.45%, and 27.61% less power was consumed than in cryogenic conditions at 80, 90, and 100 m/min cutting speeds, respectively. Based on the outcomes of the work, the application of cryogenic cooling can be considered an alternative to dry and flood cooling for improving the machinability of Ti-6Al-4V alloys. [ABSTRACT FROM AUTHOR]

In the context of satisfying sustainability requirements nowadays, dry machining is one of the ideal strategies to eliminate the environmental and human health burdens of machining processes. In addition, micro-textured cutting tools are used to improve the performance of dry machining processes. Micro-textures reduce the chip-tool contact length and thus reduce friction and heat, which results in fewer cutting forces and temperature. However, the action of micro-cutting of the bottom side of the chip, which is known as derivative cutting, cuts down the gains of using textured tools, where derivative cutting leads to higher cutting forces, heat, and tool wear. This study aimed to investigate the effects of significant texture design parameters (i.e., micro-groove width) when cutting AISI 1045 steel using different machining parameters (i.e., 75 m/min and 150 m/min of cutting velocity, 0.05 and 0.10 mm/rev of feed). Three different textured cutting tool designs were prepared using the laser texturing technique and then utilized in machining experiments. In addition, the measured machining outputs were forces, power consumption, flank wear, and surface roughness. There were no marks for the derivative cutting when using the textured cutting tool with the narrowest micro-grooves according to the obtained microscopical images after the machining tests. In addition, the textured cutting tool, which included the narrowest micro-grooves, showed better performance compared to the non-textured cutting tool and the other textured tool designs in terms of cutting and feed forces, power consumption, flank tool wear, and surface roughness at the used cutting conditions. This confirmed that the careful optimal design of the micro-textured tools can reduce or eliminate the severity of the derivative cutting, and thus improve the overall machining performance. [ABSTRACT FROM AUTHOR]

After applying high-frequency vibration of micro-displacement to the tool of the common turning method, it has a significant positive effect on improving the machinability of the machined material, but the high-frequency vibration amplitude will make the tool produce a serious plowing effect and impact effect; it will not only shorten the tool life but also affect the processing force and surface roughness. As one of the main factors affecting the plowing effect of three-drive ultrasonic elliptical vibration-assisted turning, the contribution of tool geometry to the machining performance of three-drive ultrasonic elliptical vibration-assisted turning was investigated. It is considered that the tool nose radius, tool sharp angle, and clearance angle all have an influence on the processing force and surface roughness, and among them, the effect trend of the tool clearance angle on the two is obviously different from the tool nose radius and sharp angle. As one of the main factors affecting the impact effect of three-drive ultrasonic elliptical vibration-assisted turning, the effect trend of workpiece geometry (length-diameter ratio) on the processing force and surface roughness formed by three-drive ultrasonic elliptical vibration-assisted turning was determined. It is found that the processing force fluctuates greatly when the three-drive ultrasonic elliptical vibration-assisted turning is used to process workpieces with large length-diameter ratios, and the average processing force and surface roughness also tend to increase. The study also found that under the same cutting conditions, the machining performance and machining system stability of three-drive ultrasonic elliptical vibration-assisted turning are better than common turning. However, the influence of the workpiece geometry on the surface roughness and processing force of three-drive ultrasonic elliptical vibration-assisted turning is more significant than that of common turning. [ABSTRACT FROM AUTHOR]

The compliant mechanism (CM)-based fast-tool servo (FTS) is used in ultraprecision machining contexts to produce high value products for technically advanced applications. Far too often, the FTS' machined products are expected to be geometrically complex with minimal form tolerance and surface roughness. Since the FTS' enclosing CM is responsible for guiding the cutting motion, its design is of utmost importance in determining the quality of the machined product. The objective of this paper is therefore to review specifically the design and structural related aspects of CM-based FTS that affects its ultraprecision machining performance. After a brief introduction, the fundamentals for designing ultraprecision capable CMs such as flexure hinge modelling, actuator selection and isolation and CM designing are comprehensively explained. In the subsequent section, the various configurations of CM-based FTSs that exist so far and their functionalities are listed. The critical factors which impact the CM-based FTS' ultraprecision machining performance are identified and mitigating measures are provided wherever possible. Before concluding, the research questions that should be investigated for raising the state of the art of CM-based FTSs are presented as food for thought. With this review article, not only can practitioners have a clearer picture of how better to design their CMs for their FTSs, but they can also improve upon existing FTS designs from leading researchers so that products of higher quality than before can be made for the future. [ABSTRACT FROM AUTHOR]

Electro-discharge machining (EDM) is a useful non-conventional machining operation frequently applied to make different complex geometries in any conducting material. The objectives of the present paper are to study the effect of a variation of thermo-physical properties (TPP) of three different tool materials on EDM performances. The different performances compared in this paper are: material removal rate (MRR), tool-wear rate (TWR), surface roughness (SR), radial overcut (ROC), surface-crack density (SCD) and surface hardness. Two of the most widely used work piece materials, such as corrosion-resistant austenitic stainless steel (SS316) and high strength corrosion-resistance titanium alloy (Ti-6Al-4V), are machined with the help of three different tools by varying input current and maintaining constant pulse-on time, pulse-off time and flushing pressure. Microstructural studies of the tool tip surface after machining have also been carried out. It is found that among these three tool materials, the copper tool showed the best machining performance with respect to material removal rate, radial overcut, surface finish and surface-crack density. This work will help industry personnel to choose a suitable tool for a specific work piece material. [ABSTRACT FROM AUTHOR]

This study assessed the machining properties of 11-year-old Eucalyptus urophylla × E. grandis, known as E. urograndis wood, that was infected by stem canker disease, Chrysoporthe deuterocubensis. Instead of being discarded directly, the study aimed to explore the possibility of infected trees being used in other applications such as furniture. Sawing, planing, and boring properties as well as the surface roughness of the healthy and infected trees were evaluated. The samples were collected from infected and healthy trees and classified according to the severity of the attack: healthy (class 1), moderately infected (class 2), severely infected (class 3), and very severely infected (class 4). Prior to sawing, planing, and boring, the samples were prepared according to ASTM D 1666-11 Standard Test Methods for Conducting Machining Tests of Wood and Wood-Base Materials. All samples were sawn, planed, and bored and were evaluated for their respective machining quality. The surface roughness of the machined samples was also assessed. Overall, E. urograndis of different infection severity has very good machining properties ranging from Grade I to III. Fuzzy grain, chip grain, chip mark, and tear out are the most commonly seen physical defects. As for surface roughness, healthy trees have lower surface roughness compared to that of infected trees, which indicates a better surface quality. The findings of this study suggested that infected E. urograndis can still be used in many applications. The results of this study will provide us with better knowledge about the machining performance of disease-infected E. urograndis wood and its possibilities to be used as raw material for the wood products industry. [ABSTRACT FROM AUTHOR]

The industry anticipates technological advancements for productivity improvement, and this can be accomplished by improving the machining performance in the areas where machinability challenges exist. The machinability and productivity of wire electric discharge machining (WEDM), which is a popular non-conventional cutting process, can be improved while having comparable surface integrity. Previously the non-conventional machining literature is focused on the machinability investigations of various industrial materials and process optimization. However, no extensive research on the study of flushing parameters optimization to improve machinability in non-conventional machining is known. In this research, WEDM of M42 HSS using controlled flushing is performed resulting in improved machinability in terms of material removal rate (MRR), surface roughness (Ra), and kerf width (KW). The findings indicate that the nozzle diameter (76.85%) has a substantial influence on total machining performance. Nozzle diameter, nozzle-workpiece distance, servo voltage, and flushing pressure all had a substantial influence on MRR, with percentage contributions of 34.50%, 26.02%, 22.94%, and 14.21%, respectively. Furthermore, multi-response optimization is also performed and depicts the possibility of achieving optimized values of MRR, Ra, and KW simultaneously. The flush-controlled machining improved work quality in terms of accurate production, increased productivity by lowering process time, and improved surface integrity of the machined piece thus can be a possible process advancement in the aerospace and automotive industries. [ABSTRACT FROM AUTHOR]

The high-purity G5 graphite material is widely used for glass moulding and provides high hardness and brittleness because it is sintered to fine particles unlike other graphite materials. Hence, tool cutting of a G5 workpiece is performed by local fracture instead of plastic deformation of the machined surface. Although a diamond-coated tool with outstanding hardness is used to machine very hard graphite, the tool shows variability regarding the service life and machining performance depending on the grain size, even in the same machining environment. We investigated the wear and change trend of machined surface roughness considering microcrystalline diamond (MCD) and nanocrystalline diamond (NCD)-coated tools, which are generally used to machine graphite materials, and analysed their relation with coating. For rough machining, the MCD-coated tool, for which the delamination of coating occurred later, showed less wear and improved machined surface roughness. For precision machining, the NCD tool showed less tool wear rate relative to the cutting length, leading to a small difference in the machined surface roughness between the two tools. We conclude that if rough and precision machining processes are performed using the same cutting tool, the MCD-coated tool is advantageous in terms of service life, while the difference in roughness of the final machined surface between the tools is negligible. [ABSTRACT FROM AUTHOR]

For improving energy efficiency of machining process, extensive studies focused on how to establish energy consumption model and optimize cutting parameters. However, the existing methods lack a systematic method to promote the widespread use of energy efficiency methods in industry. This paper proposes a systematic method integrating energy model, experiment design, and multi-objective optimization model. Firstly, the energy model is established considering cutting energy and non-cutting energy. Then, the orthogonal experiment is designed with the three levels of four factors of spindle speed, feed speed, cutting depth, and cutting width in the X and Y cutting directions. The data of energy consumption, surface quality, and machining time are obtained to study the effects of different cutting elements and cutting directions. Meanwhile, the standby, spindle idling, feed, SEC (specific energy consumption), material cutting, and idling feed models of the CNC machine tools are established based on the experimental data. Additionally, five sets of experimental data are tested for verifying the accuracy of the established energy consumption model, which can reach 99.4%. Finally, a multi-objective optimization model for high efficiency and energy saving of processing process is established to optimize the cutting parameters considering energy consumption, processing time, and surface quality simultaneously. Combining the case of milling with constraints including machine tool performance, tool life, processing procedures, and processing requirements, the Pareto solution set is used to solve the Pareto of the target model. Through drawing a three-dimensional needle graph and two-dimensional histogram, the optimal cutting parameter combination for rough machining and semi-finish machining is provided assisting in promoting the application of the sustainable techniques in the industry. [ABSTRACT FROM AUTHOR]

The development and application of wire electrochemical micromachining (WECMM) technology have become a research hotspot of non-traditional machining. However, a series of problems cannot be eliminated due to the machining products of micromachining gap, which leads to poor machining performance. This paper proposed a new method named ultrasonic vibration–added wire electrochemical micromachining (UA-WECMM) technology, which can solve the mass transfer problem in WECMM with extremely narrow gap. Firstly, the flow field of machining gap was simulated. The results showed that the pressure range of machining gap was larger and was more conducive to the renewal of electrolyte when ultrasonic vibration was added. Secondly, the effects of ultrasonic amplitude and ultrasonic vibration object on machining accuracy and surface quality were compared by experiments, which illustrated that the machining performance was greatly improved with the increase of ultrasonic amplitude of the workpiece. The slit width can be reduced from 196.2 to 151.2 μm, and the surface roughness can be reduced from Ra 0.863 to Ra 0.259 μm. Finally, the micro-gear structure with surface roughness of Ra 0.263 μm and depth-to-width ratio of 6.7:1 was fabricated, which proved that UA-WECMM technology is an effective technology for fabricating metal microstructures with high aspect ratio and good machining quality. [ABSTRACT FROM AUTHOR]

An attempt has been made to study the influence of magnetic field on the micro hole machining of Ti-6Al-4V titanium alloy using electrochemical micromachining (ECMM) process. The presence of magneto hydro dynamics (MHD) is accomplished with the aid of external magnetic field (neodymium magnets) in order to improve the machining accuracy and the performance characteristics of ECMM. Close to ideal solution for magnetic and nonmagnetic field ECMM process, the parameters used are as follows: concentration electrolyte of 15 g/l; peak current of 1.35 A; pulse on time of 400 s; and duty factor of 0.5. An improvement of 11.91–52.43% and 23.51–129.68% in material removal rate (MRR) and 6.03–21.47% and 18.32–33.09% in overcut (OC) is observed in ECMM of titanium alloy under the influence of attraction and repulsion magnetic field, respectively, in correlation with nonmagnetic field ECMM process. A 55.34% surface roughness factor reduction is ascertained in the hole profile in magnetic field-ECMM in correlation with electrochemical machined titanium alloy under nonmagnetic field environment. No machining related stress is induced in the titanium alloy, even though environment of electrochemical machining process has been enhanced with the presence of magnetic field. A slight surge in the compressive residual factor, aids in surge of passivation potential of titanium alloy, resulting in higher resistance to outside environment. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is a non-conventional machining process which has been widely used to machine difficult-to-cut materials. However, the efficiency of EDM hole making processes is low, and the quality of drilled holes is a concern especially when machining deep blind holes due to the poor removal of debris in the discharging gap. In this study, a new strategy based on shape modification of the electrode was developed to address this issue by indirectly changing the flow of dielectric. The electrodes of five different shapes with identical machining area were applied to improve the debris removal during the machining process. The effects of various electrode profiles on the machining performance were investigated. Machine time, material removal rate (MRR) and electrode wear rate (EWR) were used to evaluate the machining performance. The computational fluid dynamic (CFD) software Fluent was used to simulate the flow of dielectric caused by different electrode profiles. The results show that, compared with the straight electrode, the maximum effective cutting depth of curved electrodes and long-curved electrodes increased 13.793% and 132.184%, respectively, and the MRR of stepped electrodes was significantly higher after the machining depth reached 2 mm and 4 mm for electrodes with the working length of 2 mm and 4 mm, respectively. The surface roughness was identical for holes machined by all types of electrode. However, obvious carbon adhesion can be observed at lower cutting depth for straight electrode, followed by curved and long-curved electrodes. [ABSTRACT FROM AUTHOR]

The nature of electrical discharge machining makes it difficult to predict or even measure machining performance, which is why great attention has been paid to methodologies for measuring these performances. In this work, an experimental approach for measuring machining electrical discharge performance and geometric errors was presented. This can improve the authenticity of the parameters measured. A technique for identifying machining parameters using a multi-output system based on fuzzy logic has been proposed. The objective was to determine the influence of machining parameters on the machining performance and associated geometric errors. It is shown that the fuzzy model is capable of giving results providing a good correlation between the real and predicted values. The average error of the model was approximately 1.51% for material removal rate, 3.386% for tool wear rate, 2.924% for wear rate, 5.285% for surface roughness, 4.004% for radial overcut, 4.381% for circularity, and 2.937% for cylindricity. [ABSTRACT FROM AUTHOR]

This study is focused on developing and fabricating ball micro end mills with spiral blades by using low speed wire electrical discharge machining (LS-WEDM). Firstly, the new type ball micro end mill is designed and the mathematical model of wire movement trajectory is established for optimizing machining parameters and realizing visual prediction. Then, the diameter, spiral width, and the length consistent accuracy of ball micro end mills fabricated by LS-WEDM is investigated in detail, and more importantly, the three-spiral blades ball micro end mill with the diameter of about 278 μm and the length of 1860 μm is firstly and efficiently manufactured by LS-WEDM. Besides, the micro machining performance and tool wear of LS-WEDM fabricated ball micro end mill are evaluated by conducting micro milling experiments on nickel-based single-crystal superalloy DD5 material, and experimental results revealed that the main tool wear of the new type ball micro end mill is friction wear and adhesion wear rather than diffusion wear. Furthermore, the surface roughness of machined surface can be reduced to 183 nm, which indicates that the ball micro end mills with spiral blades fabricated by LS-WEDM are significantly potential to achieve high-quality machining for complex micro structures on hard material. [ABSTRACT FROM AUTHOR]

Through numerical calculations, it could be found that when the blade surface quality reaches a certain level, the surface quality of the blade was continuously improved, and the guarantee effect on its performance would be weakened. Under this circumstance, continuing to improve the surface quality of the blade had no positive effect on the performance of the blade. Studies had shown that when the blade surface equivalent grit roughness Ks reaches 4.96 (about R a = 0.8 µm), the blade performance was close to the smooth surface of the blade, and no further processing was required to improve the surface roughness. When the surface equivalent grit Ks was greater than 4.96 µm, the surface roughness had a great influence on the blade performance. When Ks was larger than 40 µm, the negative effect is significantly increased. For the different characteristics of the blade and different processing conditions, four kinds of robot-based blade surface grinding schemes were proposed, of which the core content was the robot layout. Based on the robot group's fitting to the spatial surface and the path planning, the experimental verification was carried out. [ABSTRACT FROM AUTHOR]

To improve the machinability of Inconel 718, a lot of work has been done in the past decade by modifying tools and machining processes. However, a recently developed cryogenic-ultrasonic assisted turning (CUAT) process influencing the machinability of Inconel 718 as compared to the conventional turning process (CT) has not been conspicuously presented. This paper analyzes the machinability of Inconel 718 using indigenously developed ultrasonic assisted turning (UAT) and CUAT facilities. The influence of the UAT process of Inconel 718 on cutting parameters recommended by the industry has been investigated. Surface roughness (Ra) and power consumption are measured under the UAT process and then compared with the CT process. Particle swarm optimization (PSO) algorithm is used to identify the optimum cutting parameters to achieve minimum Ra and power consumption for UAT and CT processes. The optimized parameters are considered to confirm the usefulness of CUAT as compared to UAT and CT processes. Experimental results of this research work endorse positive effects of the CUAT process over UAT and CT processes in terms of Ra and chip morphology. Ra values under the CUAT process are reduced significantly in comparison to UAT and CT processes, respectively. UAT and CUAT processes resulted in discontinuous chips having smaller chip thickness in comparison to the CT process. The results are being shared with the local SMEs, and the industry is anticipated to be benefited in terms of improving cutting performance using CUAT and UAT. Moreover, a sustainability assessment model is implemented to investigate the effect of CUAT in terms of machining performance as well as sustainability effectiveness in a single integrated approach. [ABSTRACT FROM AUTHOR]

The specific cutting energy can characterize the machinability of the cutter for a material, and its change is a reflection of the size effect in the metal cutting process. It is critical to study the cutting process using an energy-based processing signature method with the purpose of improving the machining performance. In this paper, a specific cutting energy calculation method is presented based on a mechanistic model, and an exponential function is used to describe the trend in the specific cutting energy with the average undeformed chip thickness. A dimensionless index with value of greater than 1, referred to as the Specific Cutting Energy Index (SCEI), is proposed to address the energy efficiency of the milling process and reflect the machining performance for different machining parameters. Machining experiments with 300 M steel are conducted to validate the effectiveness of the proposed model. Analyses are performed to determine the relationships between SCEI and the material removal mode, chip morphology, tool wear rate, and surface roughness. Based on these results, a feed rate scheduling method is proposed to obtain optimal machining strategies using SCEI, which is an effective way to achieve high-performance machining. [ABSTRACT FROM AUTHOR]

This work presents a novel coolant suitable for different machining processes. The focus of this study is applying superabsorbent coolant (SAC) during milling of hardened H13 steel and evaluating the possibility of utilizing superabsorbent material as a coolant and comparing with dry and flood conditions. The use of SAC is a novel method of semi-dry machining that proves the performance of hydrogels as a coolant and opens a new window for industrial applications. The main purpose besides improving machining performance is that a suitable condition has been provided to use benefits of nanoparticles (higher thermal conductivity and lubricity) safely and prevent distribution of nanoparticles and other chemical additives in the air which can cause serious occupational and environmental problems as well. The results of machining studies indicate that SAC can considerably reduce cutting force, improve surface integrity, and increase tool life. In addition, the friction conditions at the cutting zone have been improved. The results show a lower surface roughness of the chip surface. [ABSTRACT FROM AUTHOR]

Coolant is a substance that applied in a machining process for the efficient machining of materials. The application of coolants is based on the several factors including the types of machining process, workpiece material, cutting tool and cost. Coolant helps to dissipate the heat that can be generated during the machining operation, induce lubricating effects to decrease the friction caused by the interfaces of two surfaces, flush away chips and offer corrosion protection. With the right type of coolants used, the performance of machining applications and the attributes of workpieces can be remarkably enhanced. The objective of the study to provides a critical review on the mechanism of coolant penetration, functions, variety of coolants, cooling actions, effectiveness, applications, and the additives that alter the ability and properties of coolants. Furthermore, the critical review also addresses the new technology cryogenic machining that uses cryogenic gases as coolants instead of conventional coolants. [ABSTRACT FROM AUTHOR]

Many microslits are typically manufactured on quartz substrates and are used to improve their industrial performance. The fabrication of microslits on quartz is difficult and expensive to achieve using recent traditional machining processes due to its hardness, electrically insulating nature, and brittleness. The key objective of the current study was to demonstrate the fabrication of microslits on quartz material through a magnetohydrodynamics (MHD)-assisted traveling wire-electrochemical discharge micromachining process. Hydrogen gas bubbles were concentrated around the entire wire surface during electrolysis. This led to a less active dynamic region of the wire electrode, which decreased the adequacy of the electrolysis process and the machining effectiveness. The test results affirmed that the MHD convection approach evacuated the gas bubbles more rapidly and improved the void fraction in the gas bubble scattering layer. Furthermore, the improvements in the material removal rate and length of the cut were 85.28% and 48.86%, respectively, and the surface roughness was reduced by 30.39% using the MHD approach. A crossover methodology with a Taguchi design and ANOVA was utilized to study the machining performance. This exploratory investigation gives an unused strategy that shows a few advantages over the traditional TW-ECDM process. [ABSTRACT FROM AUTHOR]

Electrical Discharge Machining (EDM) consists of a non-conventional machining process, which is widely used in modern industry, and especially in machining hard-to-cut materials. By employing EDM, complex shapes and geometries can be produced, with high dimensional accuracy. Titanium alloys, due to their unique inherent properties, are extensively utilized in high end applications. Nevertheless, they suffer from poor machinability, and thus, EDM is commonly employed for their machining. The current study presents an experimental investigation regarding the process of Ti–6Al–4V ELI with high power EDM, using a graphite electrode. Control parameters were the pulse-on current (Ip) and time (Ton), while Machining performances were estimated in terms of Material Removal Rate (MRR), Tool Material Removal Rate (TMRR), and Tool Wear Ratio (TWR). The machined Surface Roughness was calculated according to the Ra and the Rt values, by following the ISO 25178-2 standards. Furthermore, the EDMed surfaces were observed under optical and SEM microscopy, while their cross sections were also studied in order the Average White Layer Thickness (AWLT) and the Heat Affected Zone (HAZ) to be measured. Finally, for the aforementioned indexes, Analysis Of Variance was performed, whilst for the MRR and TMRR, based on the Response Surface Method (RSM), semi-empirical correlations were presented. The scope of the current paper is, through a series of experiments and by employing statistical tools, to present how two main machining parameters, i.e., pulse-on current and time, affect major machining performance indexes and the surface roughness. [ABSTRACT FROM AUTHOR]

In this work, an extensive analysis has been presented and discussed to study the effectiveness of using different cooling and lubrication techniques when turning AISI 1045 steel. Three different approaches have been employed, namely dry, flood, and minimum quantity lubrication based nanofluid (MQL-nanofluid). In addition, three multi-objective optimization models have been employed to select the optimal cutting conditions. These cases include machining performance, sustainability effectiveness, and an integrated model which covers both machining outputs (i.e., surface roughness and power consumption) and sustainability aspects (carbon dioxide emissions and total machining cost). The results provided in this work offer a clear guideline to select the optimal cutting conditions based on different scenarios. It should be stated that MQL-nanofluid offered promising results through the three studied cases compared to dry and flood approaches. When considering both sustainability aspects and machining outputs, it is found that the optimal cutting conditions are cutting speed of 147 m/min, depth of cut of 0.28 mm and feed rate of 0.06 mm/rev using MQL-nanofluid. The three studied multi-objective optimization models obtained in this work provide flexibility to the decision maker(s) to select the appropriate cooling/lubrication strategy based on the desired objectives and targets, whether these targets are focused on machining performance, sustainability effectiveness, or both. Thus, this work offers a promising attempt in the open literature to optimize the machining process from the performance–sustainability point of view. [ABSTRACT FROM AUTHOR]