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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]

In the present era, the concept of Industry 4.0 plays a significant part in improving the efficiency, quality, and utilization of resources by automation and enabling intelligent operations in manufacturing processes. As a result, there is a requirement to develop an environment that improves efficiency as well as quality in order to accomplish net zero in manufacturing. The objective of powder mixed electric discharge machining (PMEDM) is to enhance the quality of the surface and machining efficiency of traditional electrical discharge machining. The PMEDM method was applied to TZM-molybdenum superalloy in the present investigation by incorporating silicon carbide particles into the dielectric medium. Powder concentration, peak current, pulse on time, pulse off time, and gap voltage were the considered input variables for the investigation. The impacts of the input variables on the surface of the specimen's roughness and the rate of material removal (MRR) were examined. The experiment model was built using response surface methodology. To find out if the input factors were significant with regard to each response, an analysis of variance (ANOVA) was performed. Powder concentration, pulse current, gap voltage, and pulse on time are found to be the important input variables for both surface roughness and MRR based on ANOVA analysis. [ABSTRACT FROM AUTHOR]

Longitudinal ultrasonic vibration-assisted high-speed dry milling (LUVAHSDM) is adopted to improve the cutting performance and surface quality of Ti-6Al-4V (TC4). Multifaceted comparisons are presented in terms of milling force, milling temperature, tool wear, 3D surface roughness, and residual stress, utilizing AlCrN, AlCrSiN, AlTiN, and AlTiSiN-coated tools. The results show that the maximum milling forces in the feed and longitudinal directions both decreased at first and then increased with the increasing of Al element contents, during which the single edge and average flank wear increased. Therefore, the surface roughness of TC4 becomes more uniform using AlTiN-coated tools, and the residual stress is significantly reduced to 98.57 MPa. Combining the results of milling force, milling temperature, tool wear, 3D surface roughness and residual stress data, it is found that AITiN-coated tools achieve excellent cutting performance and surface quality. The excellent machining performance of coated carbide tools demonstrates the feasibility and effectiveness of applying LUVAHSDM methods. [ABSTRACT FROM AUTHOR]

Accurately characterizing the surface topography of parts is crucial to improve the surface measurement accuracy and analyze the surface contact performance. A method is proposed to separate the morphological characteristics of the actual machined surface based on the layer-by-layer error reconstruction method and the signal-to-noise ratio method during the wavelet transform process, so as to evaluate the contact performance of the different joint surfaces. First, the actual machined surface morphological features are separated by using the wavelet transform method, the layer-by-layer error reconstruction method, and the signal-to-noise ratio method. Second, the reconstructed three-dimensional surface contact model is established by the reverse modeling engineering method. Third, the finite element method is used to analyze the impact of processing methods and surface roughness on contact surface parameters. The result demonstrates that the simplified and efficient three-dimensional reconstructed surface is achieved based on the real machining surface in contrast to other existing approaches. The surface roughness has a more significant influence on contact performance. The contact deformation increases with the increase of surface roughness, while the curves of average contact stress, contact stiffness, and contact area have the opposite trend. [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]

In this paper, a novel mask electrochemical additive and subtractive combined manufacturing technique was proposed. This is a machining method at the atomic level, and it can be used to produce metal microstructures with high-profile accuracy and low surface roughness. Due to the accumulation of electric field lines during mask electrochemical deposition, the height of the edges of the microcolumns is usually twice or more than the height of the central position in the deposition plane. A combined machining method based on the electric-field constraint of the mask is thus proposed to improve the accuracy of the profile and its surface roughness. The feasibility of the proposed method was verified by both simulations and experiments. The height difference between the column center and the surrounding layer on the surface of nickel microcolumns was reduced from 13 to 2 µm, and the roughness of the tops of the microcolumns was also improved. Experiments to examine electrolysis leveling were carried out to verify the correctness of the results of the simulations and theoretical calculations. Finally, the parameters were optimized using orthogonal experiments, and an array of nickel microcolumns with a diameter of 200 µm and a height of nearly 50 µm was obtained using these optimal parameters. The profile accuracy and surface roughness of the high-precision microcolumn array were improved by using the mask electrochemical additive and subtractive combined machining technique, and a high-precision microcolumn array structure was manufactured. [ABSTRACT FROM AUTHOR]

The present study investigates the CNC milling performance of the machining of AISI 316 stainless steel using a carbide cutting tool insert. Three critical machining parameters, namely cutting speed (v), feed rate (f) and depth of cut (d), each at three levels, are chosen as input machining parameters. The face-centred central composite design (FCCCD) of the experiment is based on response surface methodology (RSM), and machining performances are measured in terms of material removal rate (MRR) and surface roughness (SR). Analysis of variance, response graphs, and three-dimensional surface plots are used to analyse experimental results. Multi-response optimization using the data envelopment analysis based ranking (DEAR) approach is used to find the ideal configuration of the machining parameters for milling AISI 316 SS. The variables v = 220 m/min, f = 0.20 mm/rev and d = 1.2 mm were obtained as the optimal machine parameter setting. Study reveals that MRR is affected dominantly by d followed by v. For SR, f is the dominating factor followed by d. SR is found to be almost unaffected by v. Finally, it is important to state that this work made an attempt to successfully machine AISI 316 SS with a carbide cutting tool insert, to investigate the effect of important machining parameters on MRR and SR and also to optimize the multiple output response using DEAR method. [ABSTRACT FROM AUTHOR]

Polytetrafluoroethylene (PTFE) plays an important role in semiconductor manufacturing. It is an important processing material for the key sealing components in the field of immersion lithography. The lack of research related to the mechanical processing of PTFE leads to many challenges in producing complex parts. This paper conducted a drilling experiment on PTFE. The effect of cutting parameters on the drilling performance was investigated. Thrust, torque, surface roughness, and drilling temperature were used to evaluate the influence of cutting parameters on drilling performance. In addition, the empirical mathematical models of thrust and torque were developed using analysis of variance (ANOVA). The results indicated that the spindle speed had the most important effect on the thrust and the feed rate had the most significant effect on the torque. The lowest values of thrust and torque were, respectively, 22.64 N and 0.12 Nm, achieved in the case of spindle speed of 5000 rev/min, and feed rate of 50 mm/min. The surface quality is also best at this cutting parameter. Studies have shown that higher spindle speeds with lower feed rates are ideal parameters for improving the drilling performance and machining quality of PTFE. In addition, it was found that the temperature differences due to different drilling depths were related to chip accumulation. Surface roughness inconsistencies at various locations in the inner wall of the hole were influenced by chip adhesion during machining. This paper provides a suggestion for optimizing cutting parameters and hole quality. [ABSTRACT FROM AUTHOR]

Micropatterned surfaces perform a significant role in the performance of microfabricated devices. Maskless electrochemical micromachining (EMM) is a unique prevalent technique for creating linear micropatterns with précised geometric dimensions and surface quality. However, this method is an advanced micromachining method for fabricating linear micropatterns in comparison to traditional EMM and photolithography, both being costly during mass production. This advanced method is more significant owing to the fabrication of many micropatterned samples with a reusable insulated tool. In this research work, SU-8 2150 mask is re-used many times and produced high quality micropatterns. The developed upward perpendicular cross flow system is utilized for identical micropattern production. Micropatterned properties such as material removal rate (MRR), width overcut, depth, and surface roughness (Ra) are influenced by EMM process variables such as voltage, machining time, inter-electrode gap (IEG), and electrolyte concentration. In addition, to determine the optimal parametric mix, an effective methodology known as Measurement of Alternatives and Ranking according to Compromise Solution (MARCOS) is used. The attained optimum process variables are voltage of 10V, IEG of 100µm, concentration of 15g/l, and machining time of 3 min for creation of good quality micropatterns. In addition, validation experimentation is conducted at identified optimal parametric values that confirm improved machining performance. [ABSTRACT FROM AUTHOR]

To improve the machining performance of different processing materials, a three-excitation ultrasonic spatial vibration-assisted turning system is proposed, which realizes the non-unity of the plane where the cutting trajectory of the tool is located. The influence and formation law of three-excitation ultrasonic spatial vibration-assisted turning on the surface roughness of the workpiece under different vibration parameters (amplitude) and machining parameters (cutting speed, cutting depth, and feed) were analyzed by response surface methodology. The results show that in terms of vibration parameters, the influence of ultrasonic vibration applied in the horizontal direction on surface roughness is significantly greater than that of ultrasonic vibration applied in the vertical direction, while the feed has the greatest influence on surface roughness, followed by cutting speed. The surface roughness of common turning, one-dimensional ultrasonic vibration-assisted turning, ultrasonic elliptical vibration-assisted turning, and three-excitation ultrasonic spatial vibration-assisted turning was theoretically analyzed and experimentally compared. The results show that compared with the other three turning methods, the three-excitation ultrasonic spatial vibration-assisted turning can obtain a lower surface roughness and have good machinability. [ABSTRACT FROM AUTHOR]

At present, solar energy is the key development of clean energy. Diamond wire sawing (DWS) is the most used processing method of solar crystalline silicon cell wafer. In recent years, the application of crystalline silicon cutting that can be applied by single wire has gradually turned to that of EDWS. However, the research on the equipment and process requirements of endless diamond wire is limited, and the mastery of the equipment factors affecting the performance of EDWS is not perfect. This paper takes the influence of some constituent factors of EDWS equipment on processing performance as the research object; focuses on the analysis of the wire length, wire brand, guide wheel diameter, cutting wheel span, driving wheel position, and wheel number of the EDWS system; and finds out the deep causes and correlation of the influencing factors. It provides a basis for giving full play to the performance of endless wire sawing from the equipment composition. [ABSTRACT FROM AUTHOR]

The Ni-base single crystal superalloy DD5 is commonly employed in critical parts of turbine blades and turbine disks in aeronautical engines. To improve the surface machining quality, single-factor experiments were carried out to investigate the changes of grinding force, surface morphology, and chip morphology under different grinding conditions (dry, conventional flood, minimum quantity lubrication). The experiments showed that the conventional flood lubrication and minimum quantity lubrication (MQL) could enormously reduce the surface roughness, grinding force, and work-hardened layer thickness of DD5. At the depth of 5 ~ 15 μm, the DD5 subsurface microhardness decreased sharply with the increase of depth, and the microhardness under different grinding conditions was in the order of dry grinding, conventional flood, and MQL. However, at the depth of 20 ~ 150 μm, the DD5 subsurface microhardness tended to equilibrate and fluctuate around 540 HV. In addition, compared with dry grinding, the degree of chip serration was obvious in flood or MQL environment, and its chip formation frequency fluctuated less and chip formation was stable. Within the experimental parameters, the MQL grinding machining method obtained the lowest surface roughness and the highest surface quality with the lowest associated cost, which is the ideal grinding and cooling lubrication method for the Ni-base single crystal superalloy. [ABSTRACT FROM AUTHOR]

Anti-abrasion thin-film-coated tool is well known for its enhanced micro machining performances. However, coating increases tool edge radius, which spurs additional ploughing and rubbing. Therefore, selecting appropriate thin-film thickness and suitable abrasion-resistant coating material for micro tool is necessary to reduce friction and size effects together. To meet these objectives, first, single-layer TiAlN coating having various thin-film thicknesses has been deposited on uncoated micro end mills by PVD process. By analyzing the cutting force, surface quality and edge radius of both fresh and worn tools in micro milling of P-20 steel, appropriate thin-film thickness has been found to be ≈ 1 μm. Next, single layer TiN and diamond-like-carbon (DLC) coating of thickness ≈ 1 μm have been coated on uncoated WC tools. Then coefficient of friction (COF) and hardness of all coated and uncoated surfaces are assessed. Finally, the performance of all the coated and uncoated tools have been evaluated analytically and experimentally by analyzing dynamic stability and machinability, respectively. All the coated tools manifested enhancement in performance by uplifting stability limit and reducing tool wear, cutting forces, surface roughness and burr heights compared to the uncoated tool. Owing to the least COF, the DLC-coated tool exhibited the best performance by uplifting stability limit by 23.37% and reducing cutting force, surface roughness and burr height by 27.35%, 67.7%, and 30.58%, respectively. However, for a long machining length (1200 mm), the DLC-coated tool could not exhibit such performance as compared to TiAlN-coated tool due to significant delamination. [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]

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]

Ti-6Al-4 V alloy is widely used in many fields due to its excellent properties. However, its further applications are limited by its low hardness and poor wear resistance. In this paper, gas–liquid mixed electrical discharge machining (G-LEDM) process was applied to investigate the machining performance and surface modification Ti-6Al-4 V alloy. The effect of peak current and pulse duration on surface morphology, surface roughness, cross section morphology, micro hardness, and wear resistance were investigated using nitrogen mixed special oil dielectric. The results indicated that the G-LEDM process has better performance with fewer pores, shallower and larger craters on smoother surface. A continuous and thicker recast layer was obtained on G-LEDM process. The X-ray diffraction results demonstrated that TiN phase was formed on the sample surface. The micro hardness of G-LEDM process was about 1329.5 HV, which is about 3 times that of the matrix, and the wear resistance is improved accordingly. The surface of Ti-6Al-4 V alloy was modified by G-LEDM process. [ABSTRACT FROM AUTHOR]

Wire electrical discharge machining (WEDM) technology is a special electrothermal processing method that can precisely production of parts with variable stiffness with sharp edges or production of complex geometric parts which are difficult to produce by traditional manufacturing methods. It has an important place in production sector in terms of low energy consumption. In this study, the relationship between processing parameters on surface quality on the ferritic ductile cast iron (GGG-40) material in WEDM process with molybdenum wire was investigated by Response Surface Methodology (RSM). The aim of this study is to determine the optimum process parameters for low-cost production of GGG-40 material with sharp-edged and complex geometry parts using the WEDM method. In experimental works, surface roughness, and process time were investigated using table feedrate, pulse on time, and pulse space as cutting parameters. The surfaces obtained as a result of the experiments were evaluated in terms of surface quality with Scanning Electron Microscopy (SEM), and surface roughness device. According to the findings, it has been observed that the surface roughness has increased with increasing table feedrate, and pulse on time, and surface roughness decreased with pulse space increasing. Also, it is understood that pulse on time is the most important factor effecting surface quality. It has been found that the process time depends on only the table federate where they are inversely proportional. As result of RSM analysis, optimum cutting parameters were obtained in terms of lowest surface roughness, lowest process time and best time/performance condition on both parameters for ferritic ductile cast iron in WEDM process. [ABSTRACT FROM AUTHOR]

In the current work, an experimental study has been carried out in order to evaluate the influence of cutting settings on surface roughness and tangential force, when turning of X210Cr12 steel using coated carbide insert with various nose radius. The ANOVA analysis has been performed to determine the effect of cutting conditions on studied outputs. The experimental data have been analyzed using S/N ratios, mean effect graphs, and 3D response surface plots. The results indicate that the cutting insert nose radius and the feed rate are the mainly affecting factors on surface roughness, while tangential force is affected principally by depth of cut followed by feed rate. Confirmatory experiments have been established after Taguchi's optimization. Mathematical prediction models have been developed using artificial neural network (ANN), and the multi-objective GWO algorithm was integrated for multi-objective optimization of Ra and Fz. It has been found that the cutting force is largely affected by the cutting depth with contribution and feed rate. Also, low feeds and cutting inserts with a large nose are useful for finishing process where low roughness is desired. Regarding the cooling mode, the minimum quantity lubrication is an interesting way to minimize lubricant quantity and protect operator health and environment with keeping better machining quality. [ABSTRACT FROM AUTHOR]

In this paper, possibility of improving high-speed reciprocating wire electrical discharge machine (HS-WEDM) machining performances using SiC nanofluids was studied. The performances of SiC nanofluid high-speed WEDM and conventional emulsion dielectric high-speed WEDM were compared. An extra dielectric circulating system was used to satisfy requirement of adding SiC nanofluids. Type of operation, dielectric medium combination, and pulse on time were taken as considerable process parameters of performance of average cutting speed (ACS), surface roughness (SR), surface morphology, recast layer thickness, and material transfer. The result showed that the SiC nanofluids dielectric medium gives a better surface quality and average cutting speed as compared to conventional emulsion dielectric. The average cutting speed increased from 16.9 to 21.22 mm2/min, surface roughness improved from 1.463 to 1.233 μm, and recast layer thickness reduced from 24.7 to 12.9 μm during the HS-WEDM multiple cutting process. The secondary discharge during SiC nanofluids multi-cutting process is the main reason for improvement of the surface quality. Furthermore, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) investigation revealed a substantial transform of carbon and silicon from SiC nanofluids to the workpiece surface. [ABSTRACT FROM AUTHOR]

In low-frequency vibration-assisted drilling (LFVAD) of CFRP/Ti6Al4V stacks, owing to the different mechanical and thermal performances of the involved carbon fiber–reinforced plastic (CFRP) composite and Ti6Al4V alloy, the short tool life of commonly used carbide (WC) tools and rapidly deteriorated machining quality are the major problems. This paper aims to explore whether the polycrystalline diamond (PCD) tool can achieve a competitive effect on drilling CFRP/Ti6Al4V stacks compared with previous CFRP drilling studies. To avoid the frequent occurrence of chisel edge fracture in LFVAD of Ti6Al4V alloy, a model of plowing behavior is established and parametric experiments based on it are performed with both PCD and WC drills. It is found that the periodically dynamic force is the major factor causing the chisel edge fracture of the PCD drill, which can be alleviated by reducing the feed rate. Besides, by using PCD drills instead of WC drills in Ti6Al4V drilling, the exit burr height, drilling diameter deviation, and surface roughness value are reduced under each given parameter. Finally, PCD and WC drill bits are used to perform a wear test on the CFRP/Ti6Al4Vstacks under optimized parameters. The PCD drill achieves superior performance, including lower wear rate, better hole quality, and higher consistency. The experiments discussed in this paper provide some suggestions for selecting tools and cutting parameters when drilling CFRP/Ti6Al4V stacks. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

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]

• 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]

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]

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]