Improvement In Material Removal Rate Research Articles

Study on the effects of ultrasonic vibration-assisted wire-EDM machining parameters on material removal rate and surface roughness of NiTiV shape memory alloy

Nickel-titanium (NiTi)-based shape memory alloys (SMAs) exhibit remarkable properties, making them increasingly demanding in various engineering and medical applications especially when these SMAs are manufactured with intricate shapes and sizes. This present study examines the machining of Ni50Ti48V2 SMA using ultrasonic-assisted WEDM with input parameters of pulse ON time (TON), pulse OFF time (TOFF), peek current (I), and servo voltage (SV) along with 20 kHz constant ultrasonic vibration on the responses of material removal rate (MRR) and surface roughness (Ra). RSM-BBD response surface methodology was used to conduct the experiments. It was inferred from analysis of variance (ANOVA) analysis, that as the peak current (I) and pulse ON time (TON) increased, the MRR increased by 65.76% and Ra decreased by 54.44%. The confirmation was carried out in USV-WEDM under optimal conditions, which shows that both the predicted and actual MRR and Ra are close to each other. When compared with conventional WEDM, the USV-WEDM shows significant improvement in MRR by 8.6% and also improved surface quality by 6.3%. The surface characteristics of Ni50Ti48V2 after machining were examined using field-emitted scanning electron microscopy, showing small irreularisation peaks and wavy surface topography at optimised parameter conditions. USV-WEDM showed a lower-order micro-hardness variation due to effective flushing of molten layer re-accumulation as compared to WEDM. When comparing the base and machined samples, the temperatures of austenite and martensite are nearly the same, indicating that shape memory effects are unaffected by the USV-WEDM process.

Performance evaluation of cold plasma and h-BN nano-lubricant multi-field coupling assisted micro-milling of aluminum alloy 6061-T651

Micro-milling has been employed in various fields due to its efficiency, flexibility, material, and structural versatility in the machining of small and high-quality parts. However, when micro-milling highly plastic aluminum alloys, it is difficult to produce a smooth surface due to the easy sticking of tools. To solve this problem, a multi-energy field coupling method of adding nano-lubricant to the micro-milling area by minimum quantity lubrication (MQL) and modifying the aluminum alloy by cold plasma (CP) was introduced. In this paper, the experiments of CP and h-BN nano-lubricant minimum quantity lubrication (NMQL) multi-field coupling assisted (CPNMQL) micro-milling of aluminum alloy 6061-T65 were carried out to analyze 3D surface roughness (Sa), tool texture, milling forces (Fx and Fy), and surface morphology. The results revealed that the CP could increase the surface microhardness and improve material removal rate; Cottonseed oil with h-BN nanoparticles exhibited superior lubricating properties; The milling forces Fx and Fy were significantly reduced; Sa (0.029 µm) under CPNMQL condition decreased by 60 %, 72.1 %, 27.5 %, and 53.2 % comparing to dry (0.104 µm), NMQL (0.04 µm), and CP (0.062 µm) conditions. In addition, the smallest and most uniform tool mark texture height and depth of 0.038 µm was obtained under CPNMQL condition, a 76.3 % reduction over dry condition.

Rapid manufacturing of copper-graphene composite EDM electrode for improved machining performance

ABSTRACT Recently, graphene has emerged as reinforcing material for copper-based electric discharge machine (EDM) tools because of its superior electrical, thermal and high melting properties. 3D printing methods to fabricate electrodes are convenient and faster compared to conventional methods. Therefore, this study investigated the fabrication of copper-graphene composite electrodes for EDM using rapid tooling and pressureless microwave sintering. The influence of graphene content on the machining performance was examined, revealing enhanced electrical conductivity and machining efficiency. Electrical conductivity of the composite electrodes having 0.25 and 0.5 wt% of graphene was higher than pure copper. Additionally, upto 89% improvement in material removal rate and upto 14% reduction in electrode wear rate was obtained. Optical study showed an improvement of upto 28% in surface finish of the workpiece machined using composite electrode having 0.25 wt% graphene. A complex shaped composite tool was successfully fabricated and machined cavity was obtained.

Experimental investigation of edge preparation for cemented carbide profile cutting tools using flexible abrasive jet polishing

This paper investigates the impact of a novel Flexible Abrasive Jet Polishing (FAJP) method on the edge preparation of profile cutting tools based on Hertz contact theory. FAJP employs flexible rubber particles encapsulating diamond micro-powders as abrasives for air jet polishing. The results indicate a significant improvement in material removal rate with FAJP compared to traditional drag finishing methods, along with superior surface quality near the tool edge. The duration of abrasive usage has the greatest impact on FAJP, depending on the specific requirements of the tool edge, with options ranging from 400 to 200 h. There exists a correlation between jet pressure and jet time, with a recommended jet pressure of 225 kPa, and different coating effects achievable by adjusting the jet time. A tool speed of 280 rpm is recommended.

Optimization of electrical discharge machining parameters for enhanced performance on inconel 718 using Cu-Ni-B4C nanocomposite electrodes and advanced modeling techniques

Abstract This paper investigate into the complex field of electrical discharge machining (EDM) to improve material removal rate (MRR), electrode wear rate (EWR), and surface roughness (SR) for the machining of Inconel 718, a difficult-to-machine superalloy. The effects of discharge current, pulse duration, and pulse interval on machining performance were assessed through experiments. Response surface methodology (RSM) and artificial neural network (ANN) models, such as RNN, LSTM, and CNN, were used to optimize. Twenty runs of confirmation experiments were used to confirm the optimal process parameters found by the created models for better machining. For Inconel 718, the novel Cu-Ni-B4C nanocomposite electrode greatly enhanced EDM performance. The ideal configuration increased MRR while decreasing wear and surface roughness. Machined surfaces were inspected using SEM and EDAX analysis. With optimal settings of 50 μs pulse duration and 90 μs pulse interval, increasing current to 8 Amps increased MRR to 0.0118 g min−1, reducing EWR to 0.001 g min−1 and SR to 3.108 μm. Compared to the RNN, LSTM, and RSM models, the CNN model had the greatest R-squared (R2) score of 0.9999, suggesting greater MRR, EWR, and SR prediction.

Mechanism of glycine and H2O action in tribochemical mechanical polishing of single-crystal gallium nitride substrate

With the rapid development of the third-generation semiconductors, environmentally friendly tribochemical mechanical polishing (TCMP) is in urgent need and has been a research hot-spot. In this work, the mechanism of glycine (Gly) and H2O action in TCMP of single-crystal gallium nitride (SC-GaN) substrate is systematically studied. The experimental results indicate that the TCMP of SC-GaN substrate with 0.75 wt% Gly exhibits a higher surface quality and a 3-fold improvement in material removal rate than that with H2O. Based on first-principle calculations, the geometric configurations and interfacial interactions of the Gly/SC-GaN and H2O/SC-GaN heterostrutures are further explored. Charge transfer analysis shows that SC-GaN with lattice distortion of 0.4 Å transfers more electrons into Gly (0.202 e) than into H2O (0.128 e), which suggests the reaction between SC-GaN and Gly is more intense under friction by abrasives. The research of differential charge density and geometric properties (bond angles etc.) demonstrates that the –COOH functional group (Gly) has a higher reactivity than the –OH functional group (H2O). Based on the above findings, a microscopic material removal model for the TCMP of SC-GaN substrate with Gly is established. These results have potential applications in the semiconductor and microelectronics industries.

Adaptive circumferential distance location of the laser energy beam in the laser-assisted turning of Al/SiC metal matrix composites

Laser-assisted turning (LAT) involves locally heating a rotating workpiece using a focused laser beam before the removal of material. A key aspect in optimising productivity with laser-assisted turning is understanding the thermal relationship between laser heating, the improved material removal rate, and machinability. Consequently, in this paper, a thermal heating and laser-assisted turning finite element model and experiments were conducted to assess the machinability of an Al/SiCp MMC workpiece, considering the circumferential location of the laser beam from the cutting point. The results confirm that laser power and cutting velocity influence the temperature profile from the laser spot to the tool point and the heat-affected depth. Positioning the cutting tool closer to the laser spot effectively reduces the Von Mises stress during cutting at higher cutting temperatures. At the same time, the experiment indicates an increased risk of directly heating the tool, which can affect the integrity of the cutting tool. The work further reveals that at specified cutting velocities, lower specific cutting energy improves the tool condition and surface quality of the machined parts. Based on a range of material removal rates and laser-specific energy density, a new criterion for optimal laser-tool circumferential distance was determined. Establishing this distance can act as a guide for the laser-assisted turning of Al/SiCp metal matrix composites and potentially other materials.

An energy concisions analytical modelling approach with experimental verification for cutting performance assessment in EDM of Ti-based superalloy

Electric discharge machining (EDM) is a stochastic process which is commonly engaged for cutting of Ti-based difficult-to-cut alloys. Experimental investigation in EDM is costly and requires significant amount of time due to the complex nature of the process. Moreover, the energy intensive nature is another criticism associated to this technique. Therefore, this research is focused on developing an energy conscious mathematical model of the process while considering the categorical parameters like type of dielectric, electrode and nano-powder along with pulse time ratio. Taguchi design of experiment (DOE) has been executed for the experimentation. The comprehensive analysis of the findings depicts transformer oil (TO) delivers a remarkable improvement in MRR and SEC in comparison to other dielectric choices. Furthermore, brass electrode stands out for achieving the best surface finish. When it comes to micro-additives, SiC exhibits substantial potential in increasing MRR, and graphite gives a better surface finish. The process has also been effectively modeled which helps to predict material removal rate (MRR), surface roughness (SR) and specific energy consumption with decent precision which is the key contribution of this study. 3D simulation for EDM illustrates that the features of the crater are defined by the liquefied region, whilst the dynamics of the mushy zone play a crucial role in controlling and characterizing the microstructure size progression. The confirmatory experimental results revealed that the use of optimized parametric combinations demonstrate 90.87% improvement in MRR, 52.07% reduction in SR and 96.19% decrease in SEC in contest to the responses’ values obtained at non-optimal settings.

A discharge plasma regulation method with spike current for electrical discharge machining

Improving material removal rate (MRR) has been one of the most important issues in electrical discharge machining (EDM). A major factor which hinders the improvement of MRR in EDM is the relatively low expulsion ratio of molten material. During a discharge process, a large portion of molten material cannot be expelled sufficiently from the molten pool but re-solidifies, ultimately resulting in a low machining efficiency. In this study, aiming at enhancing the expulsion ratio of molten material in EDM, a discharge plasma regulation method with a spike current is proposed. A novel discharge pulse shape, with a spike current aligned at pulse turn-off stage, is adopted. The transient behaviors of the discharge plasma when a spike current engaged are captured using a high-speed camera, and the morphologies of the corresponding discharge craters are also analyzed. A particle-in-cell with Monte Carlo collision simulation method is used to analyze the changes in particle state inside the plasma. It is found that the spike current applied at the stage when the plasma contracts to a smaller diameter is more conducive to facilitating molten material expulsion. The results of consecutive-pulse machining experiments verify that the proposed discharge plasma regulation method can increase MRR by at least 25.89 % for stainless steel.

Dynamic performance enhancement of machining center with epoxy granite base: Experiments and finite element simulations

Epoxy granite (EG) is used for machine building applications owing to excellent dynamic properties compared to cast iron (CI). Steel is preferred to reinforce with EG to improve the static stiffness of structures. The effects of addition of steel content on stiffness and damping properties of EG composite were assessed through a specimen level study. Subsequently, the base, which is a primary structure that affects the dynamics of the vertical machining center (VMC) was taken up for investigation. The novelty of the present work is the development of scaled down model of EG base with optimum reinforcement ratio to improve the dynamic response of VMC without compromising the static rigidity of the existing CI base. An experimental study was carried out to validate the assumption made in numerical analysis that EG is isotropic and homogeneous. The results of similitude relations revealed that the EG base exhibited sixteen times higher damping compared to CI base. The influence of EG base on the overall dynamics of VMC was assessed by performing pre-stressed finite element modal analysis and harmonic analysis. Upto seven-fold improvements in directional stiffnesses of VMC with the EG base were observed compared to VMC with CI base. The results of stability lobe diagram revealed a three-fold improvement in material removal rate for VMC with EG base compared to VMC with CI base. Thus, the proposed steel reinforced configuration of EG base has demonstrated a better dynamic performance of VMC without compromising static rigidity.

Effect of Al7075 and activated carbon reinforced composite on optimizing WEDM responses

This paper presents wire cut electrical discharge machining (WEDM) response characteristics of Aluminium 7075 (Al7075) reinforced with powdered activated carbon (PAC) composite. In recent days WEDM has become a significant machining process in targeting its benefits of contributing improved material removal rate (MRR) and low surface roughness (SR). This is due the rising need for intricate, accurate, and superior structural components, the WEDM process emerges as a formidable alternative to traditional machine tools. In this work Pulse-on time (Ton), pulse-off time (Toff), discharge current (IA) and servo speed rate (SS) are the variables to be given as input and machining responses such as MRR and SR are studied. From Analysis of Variance (ANOVA) study it is found that discharge current and servo speed is the significant parameters. The optimal desirability condition is obtained with input parameters Ip: 2000 mA; Ton: 8.9 μs; Toff: 25 μs and SS: 150 rpm for the precision machining. The optimum response parameters are found as MRR 10.46 mm3/min and SR 3.32 μm. Results shows that the model designed for the prediction of MRR produces an above 98.27% and the prediction of SR is above 97.17%. The error percentage among the experimental and predicted MRR and SR were estimated. Additionally confirmatory test is performed with optimal results achieved from response surface methodology (RSM) and desirability technique. Metallurgical tests like electron backscatter diffraction analysis (EBSD) and microstructure are conducted to confirm the surface properties and atomic force morphology (AFM) analysis is applied to clarify the structural features of machined composites. The results revealed that the variation of hard deflection is caused by depression of eroded materials on the top layers of machined surface.

Synergistic effect of abrasive friction and glycine on improving chemical mechanical polishing performance of single-crystal GaN substrate

With the rapid development of the third-generation semiconductor materials, the chemical mechanical polishing rate and surface quality of single-crystal gallium nitride (GaN) substrates have been a research hot-spot. In this work, the synergistic effect of abrasive friction and glycine (Gly) on improving the chemical mechanical polishing (CMP) performance of single-crystal GaN substrate is proposed and studied systematically. The results indicated that the polishing solutions with Gly have a 2.3-fold improvement in material removal rate (MRR) as well as scratch-free surface than that without Gly. The maximum MRR of the single-crystal GaN substrate is 129.4 nm/h with surface roughness (Ra) of 0.64 nm attained by using the polishing solutions containing only 3 wt% potassium persulfate (K2S2O8). In contrast, when Gly is added as a reaction reagent, which can be activated by abrasive friction, the maximum MRR is increased to 304.2 nm/h with Ra of 0.42 nm. Meanwhile, the epitaxial evaluation indicates that two-dimensional (2D) MoS2 grown on processed single-crystal GaN substrate has superior crystalline quality and optical properties. Finally, the polishing mechanism of the single-crystal GaN substrate using the mixed solutions of K2S2O8 and Gly is discussed. The proposed CMP method has potential applications in the semiconductor and microelectronics industries.

Multi-Objective Optimization in WEDM Process of Titanium Alloy (Ti-3Al-2.5V-2.0WC) using Desirability Approach

Recently, Titanium alloy (Ti-3Al-2.5V) reinforced with Tungsten Carbide (Ti-3Al-2.5V-2.0WC) developed using the microwave sintering process has plays a major role in mining industry. It has very good mechanical property and corrosion resistance. Due to its better strength and high melting point, it is difficult to machine in conventional machining process. Therefore, WEDM process give the solution to cut this high strength material in an effective manner. In this present work, the WEDM input variables such as Servo Voltage (SV), Pulse Time - On (PT-ON), Pulse Time – Off (PT-OFF) and Cutting Speed Percentage (CSP) are considered. L09 Orthogonal Array Matrix (OAM) is considered for experimental work. The output variables like Material Removal Rate (MRR) and Surface Roughness (SR) are considered to obtained the quality machining process. Multi objective optimization technique like Taguchi-Desirability Approach method is implemented to find the optimum input variables. The Improvement of MRR from 0.05978 g/min to 0.06420 g/min and SR from 3.812 μm to 3.452 μm are obtained using Desirability Approach.

Improving material removal rate and surface roughness in macro electrolyte jet machining of TC4 titanium alloy using tools with a converging-diverging Laval-type electrolyte channel

Improving material removal rate and surface roughness in macro electrolyte jet machining of TC4 titanium alloy using tools with a converging-diverging Laval-type electrolyte channel

Macro-electrolyte jet machining of TC4 titanium alloy using a rear-end tilt tool

Improving material removal rate and surface quality are the key issues in macro-electrolyte jet machining. The current density of the workpiece surface significantly influences material removal rate and surface quality. A novel tool with the rear-end tilted is proposed to increase the current density of the workpiece surface. The flow field simulation results demonstrate that, in comparison with standard tools, the tool with the rear-end tilted not only enables the rear-end contact with electrolyte but also enhances the rear-end electrolyte flow rate. The electric field simulation results showed that, in comparison with standard tools, the tool with the rear-end tilted enabled the rear-end to participate in the electrochemical dissolution of the workpiece surface and increased the current density of the workpiece surface. The experimental results show that the material removal rate of the workpiece is increased by 27 % and the surface roughness Ra is reduced from 6.71 μm to 2.52 μm by tools with a rear-end tilt angle of 15° compared with the standard tool. In addition, when a tool with a rear-end tilt angle of 15° is used to process the plane structure, the protrusion phenomenon of tool marks at the intersection of parallel trajectories with a step-over of 9.25 mm is the smallest, with a protrusion phenomenon of 0.092 mm.

Analysis and development of elliptical tool path in trochoidal milling

Trochoidal milling has been developed to extend the cutting tool life as compared to conventional milling. It is widely used in the machining of slots and corners of molds and dies. There are several tool paths typically used in trochoidal milling such as true, circular, variable-feed, and variable-step trochoidal tool paths. However, these paths suffer from low material removal rates, low surface qualities, high CPU processing times, and/or the requirement of high-dynamic machine tools. Elliptical trochoidal tool path showed its capability to improve the material removal rate, but the expected low surface quality of the produced slot. In this paper, the elliptical tool path will be analyzed analytically and experimentally. The effect of elliptical tool path on material removal rate, cutting forces, walls waviness, and surface roughness have been investigated. A novel linear elliptical-based tool path has been proposed to enhance the elliptical tool path performance by improving both material removal rate and surface quality. A Performance index has been utilized to evaluate the performance of these processes. An analytical model for the local maximum chip thickness in elliptical tool path has been conducted to correlate this path with the cutting forces. The slot walls waviness has been modeled based on the cutting tool path geometry and validated experimentally with error less than 11%. The experimental results showed that the elliptical tool path improved the material removal rate by 11%, with a slight reduction in the maximum resultant cutting force by 3%. On the other hand, the walls waviness and surface roughness have been increased by 45% and 38% respectively as compared to the typical true trochoidal tool path. The introduction of linear paths at the elliptical path sides in the linear-elliptical tool path improved the performance index about 18 times by improving the material removal rate, waviness, and surface quality by 5%, 300%, and 74% respectively, without a significant effect on cutting forces. Therefore, the novel linear-elliptical paths are promising tool paths in increasing the performance of trochoidal milling due to the improved material removal rate, walls waviness, and surface quality, without a significant effect on cutting forces, which will improve the process machinability and cost-effectiveness.

Chemical mechanical polishing of silicon carbide (SiC) based on coupling effect of ultrasonic vibration and catalysis

Polishing SiC is a difficult task due to its exceptional chemical stability and high hardness. While the strong catalytic performance resulting from the coupling effect of ultrasonic vibration and catalysis is well-known, there have been limited studies on its effectiveness for SiC chemical mechanical polishing. To address this gap, we present a novel approach that utilizes the coupling of ultrasonic vibration and catalysis for SiC polishing. The hydroxyl free radical (*OH) generated by coupling effect is analyzed using ultraviolet-visible spectrophotometry (UV–VIS) to screen for a catalyst that matches ultrasonic vibration and establish a high-performance catalytic coupling system. The use of ultrasonic vibration in SiC polishing results in a significant increase in catalytic efficiency, with a doubling effect observed. Additionally, the catalyst itself increases ultrasonic efficiency by 43.1 %, leading to a substantial improvement in material removal rate (MRR). We study the impact of the placement of the ultrasonic vibration device on MRR and evaluate the performance of the coupling system used for polishing. Also, we delved into the removal mechanism of SiC by utilizing XPS and nyquist plots. Our findings reveal a maximum MRR of 214.6 nm/h, which improves the efficiency of commercial slurry by 80.0 %. Furthermore, the proposed strategy increases the MRR of commercial slurry by more than 70 % in the time range of 0–1 h, 1–2 h, and 0–2 h. The surface roughness (Ra) measured by AFM using a scanning area of 1 × 1 µm2 at sub-angstrom scale (Ra=0.0627 nm) is achieved. This study significantly improves the polishing efficiency of commercial slurry and has great application prospects.

Atomic scale investigation of notch evolution on 4H-SiC under different cutting surfaces and environments

Due to the hardness and brittleness of silicon carbide, the surface defects of 4H-SiC are easily transferred to the machining stage. To better illustrate the influence of pre-existing notch on cutting process, the notch evolution on 4H-SiC under different cutting surfaces and environments is studied by molecular dynamics simulation. It is found that 0001 face 12¯10 basal slip is one of the most common slip systems of 4H-SiC and the basal slip is easy to start from the tip of notch. Water film can promote the evolution of notch and lead to deeper defective structures. When there is no water film, the notch will be filled with phase transformation atoms. Since the defects tend to generate and propagate along the basal plane of 4H-SiC, the subsurface damage caused by 011¯0 face cutting is much deeper. When cutting on 0001 surface, there will be massive spalling which can lead to a sharp increase in chip atoms. Thus, cutting on 0001 surface can not only reduce the depth of subsurface damage but also improve material removal rate. In addition, the basal slip is usually accompanied by long dislocation lines and more dislocation lines will be left when cutting on 011¯0 surface.

Influence of Silver-Coated Tool Electrode on Electrochemical Micromachining of Incoloy 825

Incoloy 825 alloy is often used in calorifiers, propeller shafts, and tank vehicles owing to the improved resistance to aqueous corrosion. The electrochemical micromachining process can be utilized to machine such an engineering material owing to higher precision and lower tool wear. In the present study, an investigation was performed to enhance the process of creating micro-holes using silver-coated copper tool electrodes. The sodium nitrate electrolyte was used under different levels of input parameters such as voltage, electrolyte concentration, frequency, and duty cycle with a view to improving material removal rate, conicity, overcut, and circularity. It was found that silver-coated copper tool electrode had a high material removal rate (MRR), better overcut, conicity, and circularity compared to uncoated copper tools in most cases, due to its high corrosive resistance and electrical conductivity. From SEM and EDS analysis, it was observed that better surface topography of the micro-holes is obtained with silver-coated copper tool electrode while machining Incoloy 825 alloy in the micromachining process.

Machining of Triangular Holes in D2 Steel by the Use of Non-Conventional Electrodes in Die-Sinking Electric Discharge Machining.

Electric discharge machining is relatively a slow process in terms of machining time and material removal rate. The presence of overcut and the hole taper angle caused by the excessive tool wear are other challenges in the electric discharge machining die-sinking process. The areas of focus to solve these challenges in the performance of electric discharge machines include increasing the rate of material removal, decreasing the rate of tool wear, and reducing the rate of hole taper angle and overcut. Triangular cross-sectional through-holes have been produced in D2 steel through die-sinking electric discharge machining (EDM). Conventionally, the electrode with uniform triangular cross-section throughout the electrode length is used to machine triangular holes. In this study, new designs of electrodes (non-conventional designs) are employed by introducing circular relief angles. For material removal rate (MRR), tool wear rate (TWR), overcut, taper angle, and surface roughness of the machined holes, the machining performance of conventional and unconventional electrode designs is compared. A significant improvement in MRR (32.6% increase) has been achieved by using non-conventional electrode designs. Similarly, the hole quality resulted by non-conventional electrodes is way better than hole quality corresponding to conventional electrode designs, especially in terms of overcut and hole taper angle. A reduction of 20.6% in overcut and a reduction of 72.5% in taper angle can be achieved through newly designed electrodes. Finally, one electrode design has been selected (electrode with 20 degree relief angle) as the most appropriate electrode resulting in better EDM performance in terms of MRR, TWR, overcut, taper angle, and surface roughness of triangular holes.