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The shape of the gap is narrow and thin in low-speed wire electrical discharge machining (WEDM-LS) workpiece with large thickness; it is likely that a lot of debris cannot be removed out of the gap in time, or even accumulate somewhere, which causes a poor machining stability and low processing efficiency. In this paper, ultrasonic vibration (USV) and magnetic field (MF) complex–assisted techniques are combined with WEDM-LS to improve the machining performance. The velocity and pressure of the flow field in USV-assisted WEDM-LS are analyzed according to the theory of fluid mechanics. The fluid-solid coupling model of electrode wire and working fluid, the two-phase flow model of the working fluid, and the debris are established in COMSOL Multiphysics software, and the influence of different amplitudes on motion and distribution of debris is analyzed. It is indicated by the simulation results of debris motion that the exclusion rate of debris increases by 22.5% and the debris are distributed more evenly in the discharge gap. The experiment of a USV-assisted WEDM-LS machining workpiece with large thickness is conducted. It shows that the probability of abnormal electrical discharge reduces obviously and the distribution of discharge point is more uniform, which increases the pulse utilization and discharge efficiency. In addition, the material removal rate (MRR) increases by 44.4%, the surface roughness value (Ra) reduces by 12.8% on average, the number of debris recast to the surface decreases significantly, and the micro-cracks on the machined surface of the workpiece decrease in USV-assisted WEDM-LS. [ABSTRACT FROM AUTHOR]

Axial ultrasonic vibration-assisted cutting (AUVC) has been proved to have better machining performance compared with conventional cutting methods; however, the effect of numerous and complex influencing factors on machining performance has not been clearly revealed, and a recommended combination of cutting conditions has not been proposed yet, especially for difficult-to-machine material such as Ti6Al4V alloy. This paper focuses on the experimental and theoretical investigation into Ti6Al4V machining performance with AUVC method. First, a retrospective of the separation characteristics of AUVC is provided, and the variable parameter cutting characteristics are demonstrated. The influencing factors on machining performance are classified into four categories: machining parameters, vibration parameters, tool choice, and cooling conditions. The relationship between these factors in terms of their effect on machining performance is established theoretically. Then, it describes experiments to determine the influence of these factors on cutting force, tool life, and surface roughness. For absolute influence, the orders for cutting force, tool life, and surface roughness are respectively cutting depth > amplitude > feed rate > rotation speed, rotation speed > feed rate > amplitude > cutting depth, and feed rate > amplitude > cutting depth > rotation speed. However, for relative influence, the order is unified as amplitude > feed rate > rotation speed > cutting depth. Finally, it suggests a smaller feed rate, larger amplitude, moderate rotation speed, and smaller cutting depth in addition to a WC tool coated with TiAlN and used under HPC cooling condition for optimal performance of AUVC. This recommendation is based on the theoretical analysis and experimental results of cutting force, surface roughness, and tool life. [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]

Machining of CFRP composites is usually described as a challenging process from tool life and surface quality perspectives. To achieve a flawless machined surface at reasonable cutting tool life/cost, an optimum combination of cutting tool material and geometry is the key. The cutting tool angles are of importance as these dictate the cutting mechanism as well as the cutting edge robustness and the introduction of vibration to the machining process opens up new horizons of improvement and stirs further research questions. This article investigates the effect of tools with different geometry possessing different rake angles when used in ultrasonic-assisted edge trimming operation dealing with multidirectional CFRP laminates. A full-factorial experimental design was adopted to analyze the effect of process parameters typically cutting speed, feed rate, rake angle, amplitude, and their interactions. Machining performance indicators were captured which were the cutting forces, tool wear, chip temperature, and surface roughness. The results showed that UAM mode contributed to an increase in the cutting forces, tool wear, and chip temperature compared to the conventional mode. On the other hand, UAM mode improved the quality of the machined surface. Additionally, the ultrasonic mode enhanced the material removal mechanism using a tool with a negative rake angle. [ABSTRACT FROM AUTHOR]

The use of multiwall carbon nanotube (MWCNT) reinforced polymer nanocomposites have significant importance since MWCNT enhances the aspect ratio and interface conditions of polymer materials. However, the machining aspects of carbon nanofillers are still a potential area of research. The mechanical and electrical properties of MWCNT/epoxy nanocomposites makes it a suitable alternative to conventional engineering materials. This work focused the machining characteristics optimization during drilling of MWCNT/epoxy nanocomposites using TOPSIS and GRA theory. The machining characteristics are considered which are surface roughness, torques and thrust. By using both the multi-criteria optimization techniques, all the machining characteristics aggregated into the single objective function. The effects of drilling parameters have been investigated by variance analysis. The outcomes of both the proposed module give different optimal conditions of process parameters. The confirmatory experiment carried out to validate the obtained results, and it has been observed that GRA is more feasible than TOPSIS. During machining, the cutting force rises with the high feed rate, and the lower value of feed rate reduces the surface roughness. The achieved improvements in drilling performances are highly required for an efficient machining environment. Further, a microstructural investigation was done to check the quality of the machined samples. [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]

The geometric complexity of 3D-printed parts increases the difficulty of surface finishing with the conventional grinding technique. In this study, a rotary ultrasonic-assisted abrasive flow finishing (RUA-AFF) method is proposed towards improving the performance of the AFF process by providing rotary motion and ultrasonic vibration to the equipment. Finishing experiments are carried out involving Al6061 to investigate the capabilities of the proposed RUA-AFF. The obtained results show that (1) the higher ultrasonic vibration amplitude results in the greatest improvement in the work surface quality and a higher increase in material removal rate (MRR); (2) with the higher ultrasonic frequency and rotational speed, the surface roughness and MRR are decreased marginally; (3) there are two material remove modes in the RUA-AFF process: abrasive impingement and micro-cutting. These indicate that the high efficiency and high-quality finishing of Al6061 can be performed with the proposed RUA-AFF technique. [ABSTRACT FROM AUTHOR]

Silicon carbide particle-reinforced aluminum matrix composites (SiCp/Al) are increasingly applied in high-end industries because of their excellent comprehensive material properties. However, as a typical difficult-to-cut material, machining of SiCp/Al using traditional processes faces serious challenges. Jet electrochemical machining (Jet-ECM) is a new-generation electrochemical machining (ECM) technology, which exhibits improved process flexibility and machining accuracy, in addition to the basic advantages of the ECM process. Jet-ECM appears to be a potential alternative machining technology for SiCp/Al to achieve high machining rate and damage-free surface. In the present work, the polarization curves obtained by electrochemistry study showed that a passivation-tanspassivation transition behavior with increasing the voltage occurs in NaNO3 electrolyte, while NaCl electrolyte causes active behavior. Thus, compared to NaCl electrolytes, the NaNO3 electrolyte is relatively suitable for Jet-ECM of SiCp/Al because of its potential to improve the machining localization. Besides, the effects of process parameters (including voltage, electrolyte type, and concentration) on the machining performance were systematically investigated. It was found that the voltage has the most significant influence on the machined dimple profile. A higher voltage helps in achieving a large depth. The surface roughness is dependent on the selection of the electrolyte and voltage. The NaNO3 electrolyte is preferred to realize smooth surface. Additionally, it was found that with increasing voltage, the surface roughness increases. Finally, this work was extended to be Jet-ECM with linear movement of the nozzle, and well-formed SiCp/Al grooves can be obtained using the selected process parameters. [ABSTRACT FROM AUTHOR]

Electric discharge machining (EDM) of tool steel (D2 grade) has been performed using different tool designs to produce through-holes. Machining performance has been gauged with reference to machining time, hole taper angle, overcut, and surface roughness. Inaccuracies and slow machining rate are considered as the most common limitations of the electric discharge machining (die-sinking). Traditionally, a cylindrical tool is used to form circular holes through EDM. In this study, the hole formation is carried out by changing the tool design which is the novelty of the research. Two-stage experimentation was performed. The newly designed tools substantially outperformed a traditional cylindrical tool, especially in terms of machining time. The main reason for the better machining results of modified tools is the sparking area that differs from the traditional sparking. Comparing against the performance of a traditional cylindrical tool, the newly designed tools offer a considerable reduction in the machining time, radial overcut, and roughness of the inside surfaces of machined holes, amounting to be approximately 50%, 30.6%, and 38.7%, respectively. The drop in the machining time along with a condensed level of radial overcut and surface roughness can shrink the EDM limitations and make the process relatively faster with low machining inaccuracies. [ABSTRACT FROM AUTHOR]

The droplet dynamic behavior of spraying during the manufacturing process affects tool life, cooling, and lubrication. A detailed understanding of droplet dynamic behavior is required to improve the surface quality while reducing the cutting fluid consumption. In this study, quantitative measurements for droplet diameter, number concentration, and axial velocity were carried out through a phase Doppler particle analyzer technique. The droplet characteristic spatial distributions of a standard twin-fluid nozzle (STN) and a novel twin-fluid nozzle (NTN) under different gas-to-liquid mass ratio (GLR) values were analyzed in detail. The results showed that the high-speed internal gas flow of an atomizing core has a significant effect on improving the synergistically enhanced atomization behavior, and more smaller droplets and an increased droplet momentum are easily obtained. Furthermore, a better spatial distribution of atomization characteristics can be achieved under a higher GLR of 4.3%. Furthermore, the effects of the novel atomizing core structural parameters on the droplet mean velocity spatial distribution, droplet turbulence, and root mean square velocity fluctuation were investigated. The results also showed that the improved NTN can effectively improve the spray atomization performance and droplet dynamic characteristics. In addition, comparative studies of the effect of the atomizing core structure on the machining performance were performed. Compared with the STN, the improved NTN achieves a significant reduction in cutting temperature, tool wear, and surface roughness of 17.25%, 33.96%, and 37.83%, respectively, owing to the better droplet dynamic characteristics and spatial distribution of spray atomization characteristics. [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]

Many techniques have been developed to improve the machinability of aeronautical materials titanium and nickel-based alloys such as ultrasonic-assisted turning, laser-assisted turning, and cryogenic-assisted turning. This collaborative scientific investigation presents the steps taken to gain insight into the phenomena of machining Nimonic 90 (a nickel-based alloy) alloy using ultrasonically assisted turning. The cutting speed, feed rate, depth of cut, and frequency are taken as input parameters and average surface roughness (Ra), power consumption (P), and chip formation are considered as output parameters. The experiments are carried out with the full factorial design. The UAT (ultrasonically assisted turning) process gives a significant improvement in average surface roughness and power consumption because of the intermittent cutting action of the cutting tool. UAT process shows a 70–80% reduction in average surface roughness (Ra) and a 6–15% reduction in power consumption as compared with CT (conventional turning) process. Ultrasonically assisted turning also resulted in the thin and smoother chips as compared with CT process which helps to achieve a more superior machining effect. Finite element modeling shows that the quasi-static nature of the stress induced in the UAT process leads to lower force and ultimately lower power generation. Moreover, a sustainability assessment model is implemented to investigate the effect of UAT in terms of machining performance as well as sustainability effectiveness in a single integrated approach. The novelty of this work lies in providing an integrated concept that combines experimental analysis and sustainability assessment when using ultrasonic vibrational energy during turning of Nimonic 90. [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]

In abrasive waterjet (AWJ) process, abrasive properties are of critical factors that influence machining performances. Abrasive process parameters including abrasive material, size and flow rate, exert a significant impact on cutting ability and quality of AWJ. In this paper, monolithic abrasive material (garnet, alumina and silicon carbide) and corresponding mixing abrasive materials are adopted to evaluate the effect of abrasive process parameters on the cutting ability and quality, respectively. Two kinds of cutting experiments are conducted with a monolithic abrasive to explore the influence of variation in abrasive material, size and flow rate on the machining performance. The cutting depth experiments for evaluating the cutting ability in terms of cutting depth are conducted with a right trapezoid aluminium alloy block. The kerf cutting experiments are taken to evaluate the cutting quality by the kerf taper angle, kerf width and surface roughness. On this basis, AWJ experiments with mixing abrasive materials are taken to probe into the composition of mixing abrasives' effect on cutting performance. It is found that the abrasives consisting of 75% alumina and 25% garnet in mass fraction lead to a maximum cutting depth of 41.7 mm and the smallest surface roughness of Ra 2.1 μm under the flow rate of 130 g/min. [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]

Machining performance of AISI 316 stainless steel turning under dry and spray impingement cooling environments was investigated. The input parameters such as depth of cut, feed rate, cutting speed, water pressure and air pressure were considered for the spray assisted turning with uncoated carbide inserts. All the experiments were carried out using Taguchi based L16 orthogonal array of the design of experiments. Cutting tool temperature, chip temperature, surface roughness and tool flank wear were the measured machining performance responses. The machining performance responses were simultaneously optimized using Taguchi based Weighted Principal Component Analysis approach. The optimal combination of the machining parameters under spray impingement cooling was found to be 0.2 mm depth of cut, 0.04 mm/rev of feed rate, 66 m/min of cutting speed, 3.5 bar of water pressure and 1.5 bar of air pressure. The optimized result was verified through confirmatory experiments and an improvement in the SN ratio of 18.1540 dB for Combined Quality Loss (CQL) was obtained. Machining under spray impingement cooling environment was most effective in turning AISI 316 steel in comparison with dry machining since reduction in chip temperatures were found out to be greater than 300%. [ABSTRACT FROM AUTHOR]

The study investigates the effects of variables of laser-assisted turning (LAT) and conventional turning (CT) on machining performance of 45% volume fraction silicon carbide particle reinforced 2024 aluminum matrix composites (45 vol.% SiCp/2024Al). The process benefits of laser processing variables were analyzed by comparing the surface roughness, surface microstructure and residual stress. The variables in LAT are as follows: cutting speed, feed rate, and laser power. The experimental results show that under the same cutting parameters, the LAT outperforms the CT method by reducing the surface roughness value by up to 81.73%. Unlike in CT, LAT produces more residual compressive stress. Micro-structure analysis shows that there are no microcracks on the surface of the workpiece machined by LAT. [ABSTRACT FROM AUTHOR]

The present study deals with reaming of Al6061/SiC metal matrix composite. For the fabrication of the composite, stir casting technique was used. In the castings, 5 and 10 weight percentages of Silicon Carbide (SiC) 23µm size was used as the reinforcing material. The tensile and hardness tests carried out on the specimen indicated that it increased with the addition of SiC. The images from scanning electron microscope showed the fair distribution of reinforcement. After drilling 7.8 mm diameter holes, reaming was performed with 8mm diameter straight fluted HSS reamer under dry condition at cutting speeds of 18 and 24 m/min and feed rates of 0.2 and 0.4 mm/rev. Torque required for reaming was measured using 4 component Drill tool Kistler dynamometer 9272A. The estimation of progressive wear of the reamer was undertaken using a profile projector. With the introduction of SiC as reinforcement, the wear rate of the reamer increased as the reinforcement was highly abrasive in nature. The performance of HSS machine reamer was evaluated in terms of reaming torque, tool wear and surface roughness of the hole. [ABSTRACT FROM AUTHOR]

The present study is focused on liquid nitrogen treatment of M2 tool steel for 12 hours, 24 hours, and 36 hours at -196 0C followed by tempering at 150 0C. The treated tool samples are used for machining low carbon steel on a CNC lathe to varying combinations of Spindle speed (700, 1100 & 1800 rpm), Feed rate (0.1, 0.125 & 0.15 rev/mm) and Depth of cut (0.15, 0.3 & 0.45 mm). Taguchi's Design of experiments and ANOVA methods are used to statistically analyze the effect of cutting parameters and cutting forces on the tool wear and surface roughness after experimentation. SEM analysis is carried out to investigate the type of tool wear experienced by the cutting tools. The regression analysis has resulted in a model to predict the values of surface roughness, tool wear and friction coefficient, with a maximum error of ±6% from the actual experimental values. Рад се бави М2 алатним челиком третираним теч- ним азотом у трајању од 12, 24 и 36 часова на температури од -1960 Ц код кога је потом приме- њено отпуштање на температури од 1500 Ц. Трети- рани узорци су коришћени за обраду ниско-угље- ничног челика на ЦНЦ стругу при различитим брзи- нама вретена (700, 110 и 1800 rpm), брзини помоћ- ног кретања (0,1; 0,125 и 0,15 rev/min) и дубини резања (0,15; 0,3 и 0,45 mm). Тагучијев план експе- римената и АNOVA су коришћени за статистичку анализу параметара резања и сила резања код хабања алата и храпавости површине после изве- деног експеримента. SEM анализом је испитан тип хабања код резног алата. Регресионом анализом је добијен модел за предикцију вредности храпавости површине, хабања алата и коефицијента трења са максималном грешком ±6% на основу реалних експерименталних вредности. [ABSTRACT FROM AUTHOR]

With the increased prerequisites for ecological protection, the vegetable oil and nano-fluid-based minimum quantity lubrication (MQL) technology have become a modern research trend. For instance, the palm oil exhibits superior lubricity owing to fatty acid and film-developing characteristics of the carboxyl group. Conversely, due to unique physiochemical properties of Al2O3 nano-particles, they exhibit superior lubricity during machining operations. Thus, here, it was attempted to discover the benefits of Al2O3 and palm oil–mixed nano-fluid in MQL-assisted milling of Inconel 690 for eco-benign and cleaner manufacturing. During the experiment, different concentrations (0.5–5%) of Al2O3 nano-particles were mixed with palm oil. Afterward, the performances were evaluated with respect to the surface roughness, specific cutting energy, tool wear, and cutting temperature. From an economic perspective, the determination of ideal concentration (%) of the Al2O3 nano-particle is a crucial concern. Thus, a fuzzy interference system (FIS)–based model has been developed to obtain the optimum concentration (%) of Al2O3 nano-particle. The multi-performance characteristics index (MPCI) values confirmed that 2.5% was the optimum concentration for Al2O3 in MQL milling environment. Afterward, the machining performances obtained from 2.5% Al2O3 particle concentration have been compared with dry, flood, and pure palm oil condition. It is clearly found from the comparison that MQL milling with 2.5% Al2O3 nano-particle concentration demonstrated much better machining behavior than another lubricating medium. [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]

Abstract Taguchi coupled grey relation analysis is adopted to study the effects of machining parameters of Wire Electrical-Discharge Machining (WEDM) on magnesium metal matrix composite reinforced with Reduced Graphene Oxide(r-GO). An optimal combination of process parameter was expected to be finalized in this research to attain maximum Material Removal Rate (MRR) with a minimal surface roughness (Ra) value. The composite was fabricated through solvent based powder metallurgy route for varying percentage of r-GO. Experimental combination for WEDM of developed composite specimens were finalized to be L27 orthogonal array (OA) using Taguchi's method mainly based on the control factors namely reinforcement weight percentage (wt.%), pulse ON time (P1), pulse OFF time (P2) and wire feed rate (Wfd). ANOVA results revealed that wt.% and P1 are the most influencing parameters for MRR and Ra. Outputs scaleup that the developed regression model augments well with the experimental values. Using grey relation analysis (GRA) the optimal parameter was set and the final results obtained based on the optimal combination was found to be with a maximum MRR (18.38 mm3/min) and minimum Ra (3.29 μm). Traces of intermetallic formation are identified over the machined surface due to the action of machining parameters. [ABSTRACT FROM AUTHOR]

Titanium alloys are typical difficult-to-machine materials. The experiment is conducted by turning Ti-6Al-0.6Cr-0.4Fe-0.4Si-0.01B (TC7) with PCD and PCBN tools under dry condition. The paper focuses on studying the performance of PCD tools in dry turning TC7 and investigating the machinability of TC7. Wear mechanisms of two cutting tools are analyzed and compared by scanning electronic microscopic (SEM) images of worn inserts. The effect of cutting parameters (cutting speed, feed rate and depth of cut) on tool life is studied by measuring the average flank wear with 3D super-depth-of-field instrument. The influence of cutting parameters on cutting temperature, surface roughness, and surface microhardness is also investigated. The results show that although non-uniform wear band forms on both tools of PCD and PCBN, the wear of PCBN is serious than that of PCD. The adhesion-dissolution-diffusion mechanism takes effect on two tools during machining. For PCD tool, obvious adhesion and chipping occur. For PCBN tool, adhesion, notching, and crater occur. The main conclusion is that PCD tool has better performance than PCBN tool. PCD tool is suitable for machining TC7. The machinability of TC7 is poorer than that of TC4. The hardening of workpiece surface layer occurs. [ABSTRACT FROM AUTHOR]

Electric arc sweep milling is an arc machining process derived from blasting erosion arc machining (BEAM). Purpose of this technology is to increase machining performance of open channels which are extensively used in blisks. In this process, a tool electrode slides above the workpiece surface layer by layer and erodes material by thermal effect to form a complete groove. In this paper, capability of this process is studied initially and effects of input energy on material removal rate (MRR), tool wear ratio (TWR), surface roughness as well as cross section morphology are investigated and the MRR can reach up to 8000 mm3/min with TWR of 2.9%. Based on principle of electric arc sweep milling, in order to machine a groove, there are different possibilities for tool pathway. Therefore, influence of two different tool pathways for machining a simple groove is proposed. Comparison of reciprocating and rectangle pathway shows that in the latter, machining performance improves. The reason is wider clearance between tool electrode and groove wall in rectangle tool pathway that enhances fluid flow and debris particle evacuation in the gap. Therefore, to achieve a good machining result, tool pathway should also be considered for a better fluid distribution. [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]

Heat generation in metal cutting leads to numerous problems. Despite the development of many different cooling and lubrication methods in industry, opportunities are still open to develop novel methods. Minimum quantity lubrication (MQL) is a recent such development that has shown promising results. However, the effect of aerosol temperature on machining performance has not yet been studied in depth. Thus, the aim of this study is to explore the ability to improve surface roughness in machining by lowering the MQL aerosol temperature. To study the effect of the aerosol temperature in MQL, an experimental investigation is carried out using a simple turning operation on AISI P20 and D2 steels, with cutting tools and cutting fluids (CF) typically used in industry. The arithmetic average surface roughness of the workpiece is measured for each of the treatments. Measurements are taken with dry cutting condition, conventional flood cooling method, and several MQL temperatures. Significantly lower surface roughness in the workpieces is observed for all considered MQL temperatures in comparison to dry cutting and flood cooling conditions. Furthermore, a reducing trend with a quadratic behaviour in surface roughness is observed with decreasing temperatures. The lowest surface roughness is observed at MQL 5 °C for both material. Interestingly, the effect of aerosol temperature is observed to be high with D2 steel and lower temperatures achieved up to 50% reduction in surface roughness. The study concludes that surface roughness can be reduced using low-temperature MQL. The effect of the aerosol temperature on other tool-work material combinations and tribology studies are suggested as further work. [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]

In this paper, the evolutions of cutting force, cutting temperature, and surface roughness, and the corresponding machinability in asymmetric up-milling of TC25 alloy are investigated. The results indicated that radial depth of cut generated opposite influence on the cutting force/cutting temperature versus surface roughness. The reason can be accounted as the intertwining of feed marks at low radial depth of cut, and the mechanism of hard cutting at a high radial depth of cut. Moreover, the asymmetry has a significant effect on the machinability in asymmetry up-milling TC25 alloy. Changing the asymmetry, i.e., the radial depth of cut, can alter the machinability while maintain the balanced development of various indexes. The machinability reaches the best when the radial depth of cut is ae = 8 mm. The axial depth of cut and feed per tooth should be selected as large as possible to avoid work hardening and to improve machining efficiency in asymmetric up-milling TC25 alloy. The cutting speed should be controlled within Vc = 100–120 m/min to obtain better machinability. On the basis of this research, it is expected to find optimized milling parameters to realize high efficiency milling of TC25 alloy. [ABSTRACT FROM AUTHOR]

• CMQL was proposed as an eco-friendly alternative to machine the CFRP. • The lubri-cooling mechanisms under different conditions were revealed. • CMQL indicates great potential for the machining of CFRP. Due to the hygroscopicity of CFRP, dry and/or near-dry cutting conditions instead of conventional flood lubrication is recommended for CFRP machining. However, thermal damage, poor surface integrity, and harmful dust occur when machining CFRP under dry conditions. To address the above problems, this paper aims to investigate the machining performance of CFRP laminates under cryogenic-based conditions, which are characterized as cryogenic supercritical carbon dioxide (scCO 2) and vegetable oil-based cryogenic minimum quantity lubrication (CMQL). The milling temperatures, milling forces, surface quality and surface generation mechanism were particularly studied to analyze the effect of cooling category on the milling performance of CFRP under varying cutting parameters. To reveal the underlying mechanisms of performance evolution with different lubri-cooling conditions, the basal tribology and wettability tests were innovatively carried out as a function of lubri-cooling environments. Results indicate that the minimum milling forces, milling temperatures and machined surface roughness were obtained under CMQL condition. Cryogenic cutting operation reduces the cutting temperature, increases the cutting force while improves the surface quality. The mechanism of material removal is significantly different under different tool-fiber angles. This study also demonstrated the feasibility of cryogenic cutting, especially CMQL condition to improve the surface quality during CFRP precision machining. [ABSTRACT FROM AUTHOR]

Micro electrical discharge machining (micro EDM) is able to remove conductive material by non-contact instantaneous high temperature, which is more suitable for machining titanium and its alloys compared with traditional machining methods. To further improve the machining efficiency and machined surface quality of micro EDM, the nano particle surfactant mixed micro EDM method is put forward in this paper. Experiments were conducted to explore the effect of nano particle surfactant on the micro EDM performance of titanium alloy. The results show that the material removal rate of micro EDM in dielectric mixed with TiO2 is the highest when open-circuit voltage is 100 V, followed by Al2O3 and ZrO2. Lower tool wear rate can be produced by using dielectric mixed with nano particle surfactant. The taper ratio of micro EDM in dielectric mixed with nano particle surfactant is higher than that in deionized water. The surface roughness Ra of micro EDM in dielectric mixed with TiO2 can be 50% lower than that in deionized water. It is helpful to improve the machining performance by adding surface surfactant in the dielectric of micro EDM. [ABSTRACT FROM AUTHOR]

Machining processes through cutting are accompanied by dynamic phenomena that influence the quality of the processed surfaces. Thus, this research aimed to design, make, and use a tool with optimal functional geometry, which allowed a reduction of the dynamic phenomena that occur in the cutting process. In order to carry out the research, the process of cutting by front turning with transversal advance was taken into account. Additionally, semi-finished products with a diameter of Ø = 150 mm made of C45 steel were chosen for processing (1.0503). The manufacturing processes were performed with the help of two tools: a cutting tool, the classic construction version, and another that was the improved construction version. In the first stage of the research, an analysis was made of the vibrations that appear in the cutting process when using the two types of tools. Vibration analysis considered the following: use of the Fast Fourier Transform (FFT) method, application of the Short-Time Fourier-Transformation (STFT) method, and observation of the acceleration of vibrations recorded during processing. After the vibration analysis, the roughness of the surfaces was measured and the parameter Ra was taken into account, but a series of diagrams were also drawn regarding the curved profiles, filtered profiles, and Abbott–Firestone curve. The research showed that use of the tool that is the improved constructive variant allows accentuated reduction of vibrations correlated with an improvement of the quality of the processed surfaces. [ABSTRACT FROM AUTHOR]

Duplex stainless steels are being used on applications that require high corrosion resistance and excellent mechanical properties, such as the naval and oil-gas exploration industry. The components employed in these industries are usually obtained by machining; however, these alloys have low machinability when compared to conventional stainless steels, usually requiring the employment of tool coatings. In the present work, a comparative study of TiAlSiN coating performance obtained by these two techniques in the milling of duplex stainless-steel alloy LDX 2101 was carried out. These coatings were obtained by the conventional direct current magnetron sputtering (dc MS) and the novel high power impulse magnetron sputtering (HiPIMS). The coatings were analyzed and characterized, determining mechanical properties for both coatings, registering slightly higher mechanical properties for the HiPIMS-obtained coating. Machining tests were performed with varying cutting length and feed-rate, while maintaining constant values for axial and radial depth of cut and cutting speed. The surface roughness of the material after machining was assessed, as well as the wear sustained by each of the tool types, identifying the wear mechanisms and behavior of these tools, as well as registering the flank wear values presented for each of the tested tools. The HiPIMS-obtained coating exhibited a very similar behavior when compared to the other, producing similar surface roughness quality. However, the HiPIMS coating exhibited less wear for higher cutting lengths, proving to be a better choice in this case, especially regarding tool life. [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]

Wire electrical discharge machining (WEDM) has been, for many years, a precise and efficient non-conventional manufacturing solution in various industrial applications, mostly involving the use of hard-to-machine materials like, among others, the Inconel super alloys. The focus of the present study is on exploring the effect of selected control parameters, including pulse duration, pulse-off time and the dielectric flow pressure on the WEDM process performance characteristics of Inconel 617 material, such as: volumetric material removal rate (MRR), the dimensional accuracy of cutting (reflected by the kerf width) and surface roughness (SR). The research experiment has been designed and carried out using the response surface methodology (RSM) accordingly with the Box–Behnken design scheme. The results of experiments derived in the form of a fitted regression model have been subjected to the analysis of variance (ANOVA) tests. Thus, the variable process parameters and the relevant interactions between them, characterized by a significant influence on the values of the derived output responses, could be explicitly determined. [ABSTRACT FROM AUTHOR]

Nanofluid based lubricants have immense acceptability in sustainable and eco-friendly machining of superalloys – this is due to their superior heat transfer ability. Extreme demands for sustainable manufacturing compelled the manufacturers to avail synergistic benefits with higher machinability and lower carbon footprint on the environment. For that purpose, the performance of an indigenously developed minimum quantity nano-green lubricant is investigated in milling of Inconel 690. Accordingly, nano-silica (vol% varying from 0.5 to 1.5%) was reinforced into palm oil and sprayed into the tool-chip interface through minimum quantity lubrication set up. The milling operations were executed under five different lubricating mediums: dry, minimum quantity palm oil, 0.5% silica deposited palm oil, 1% silica deposited palm oil, and 1.5% silica deposited palm oil. Comparative tool life, surface roughness, resultant cutting force, and cutting temperature were assessed. Subsequently, SEM and EDX images were analyzed to confirm the governing tool wear mechanisms. Experimental data shows that 1% silica deposited palm oil medium performs better concerning all machining responses. Furthermore, a multi-objective response surface methodology (MORSM) confirmed that speed of 88.18 m/min, feed of 0.11 mm/tooth, depth of cut of 0.50 mm, and 1%-MQNGL based lubricating condition are the optimal design parameters to achieve sustainable working environment. • The effect of nano-green lubricants on the machining performances is evaluated. • Wear mechanism of TiAlN/AlCrN coated carbide insert is examined. • A sustainable machining environment is identified using MORSM. [ABSTRACT FROM AUTHOR]

Water-based slurries with silica (SiO 2) nanoparticles, graphene oxide (GO) nanosheets and GO/SiO 2 hybrid nanostructures as abrasives were synthesised in order to achieve a high-efficiency and low-damage lapping. Tribological characteristics of SiO 2 , GO and GO/SiO 2 nanoslurries were systematically investigated to optimise slurry formulae, and the lubricating mechanisms involved were revealed based on the analyses of worn surfaces and used slurries. Machining performance of the optimised slurries was then examined in the fixed abrasive lapping of glass substrates in terms of surface quality and material removal. The GO/SiO 2 slurry of 0.16 wt.% at a mass ratio of 1:1 generated a lubricating layer consisting of C deposited and SiO 2 dynamic films at the rubbing interface. This improved friction and wear conditions at the contact, producing a significantly lower COF and a better worn surface quality than those slurries containing only GO or SiO 2. The lapping with the GO/SiO 2 slurry thus reduced the surface damage on glass and achieved a crack-free subsurface. In comparison with a conventional lapping, the new lapping process resulted in a 35% reduction in surface roughness, but a 28% increase in material removal rate. Such improvements were attributed to the synergistic lubrication behaviour of the formed nanostructures of GO/SiO 2 in water. [ABSTRACT FROM AUTHOR]

Titanium alloys are difficult-to-cut materials due to their low elastic modulus and poor thermal conductivity. To deepen the understanding of the cutting performance for Ti–6Al–4V under various eco-friendly cooling conditions, surface integrity, cutting forces, and tool wear were comprehensively investigated through cutting experiments implementing three cooling methods, namely, cryogenic gas (CG), minimum quantity lubrication (MQL), and a combination of CG and MQL (CG + MQL), respectively. The results show that the lowest surface roughness (S a = 76.71 nm) was achieved at a low spindle speed under the CG + MQL cooling conditions. This suggests that of the three cooling methods, the CG + MQL hybrid cooling method achieved the highest cooling efficiency. Compared with the MQL cooling method, the CG + MQL cooling method led to more pronounced tool wear and material adhesion due to reduced oil-based lubricity caused by low temperatures. Under the MQL cooling conditions, the elastic recovery of Ti–6Al–4V accelerated the formation of micro-cleavages on the clearance face of the diamond tool. Additionally, the depth of cut was also comparable to the tool edge radius in the micro-scale diamond turning. Compared with the conventional turning of Ti–6Al–4V, this round-edge effect, combined with the adhesion and built-up edge, led to a relatively stronger friction effect, evidenced by an increase in the coefficient of friction from 1.027 to 3.532, and higher specific cutting energy under all the cooling conditions in micro-scale diamond turning. [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]