Increase In Material Removal Rate Research Articles

Investigation of EDM erosion behavior for Ni-based superalloy using experimental and machine learning approach

The rapid growth of the global population and the consequent increase in manufacturing activities have heightened the need for sustainable practices to protect the environment. Non-traditional manufacturing processes, such as electric discharge machining (EDM), often use oil-based dielectric fluids like kerosene, which emit toxic fumes and aerosols, contributing to environmental pollution. To address this, the reuse of waste cooking oil (WCO) as a dielectric fluid in EDM presents a promising solution. This method not only tackles the issue of waste oil disposal but also supports the circular economy by repurposing waste materials. EDM, frequently criticized for its low cutting rates, can be enhanced by using nitrogen assisted modified Cu electrodes (cryogenically treated (CT)). This study focused on machining the difficult-to-cut nickel-based superalloy, IN718 by incorporating Sillimanite nano-powder with Span-60 (S-60). The erosion performance characteristics such as material removal rate (MRR), electrode wear rate (EWR), and accuracy index (AI) were evaluated. An artificial neural network (ANN) was employed to predict and correlate experimental and predicted values. Significant improvements were achieved using the non-dominated sorting genetic algorithm (NSGA-II) in the confirmation investigations. With a non-treated (NT) Cu electrode, the confirmatory experiments showed a 79.81 % increase in MRR, an 18.99 % decrease in EWR, and a 0.89 % improvement in AI. For the CT Cu electrode, MRR increased by 85.48 %, EWR decreased by 32.90 %, and AI improved by 0.53 % when using optimal processing parameters. This study demonstrates the potential for significant environmental and performance benefits in EDM by reusing WCO and optimizing electrode treatments.

Efficient evolution mechanism of electrolytic gas products from laser-assisted electrolyte jet machining

Efficient evolution of electrolytic gas products is one of the mechanisms for increased material removal rate in laser-assisted electrolyte jet machining. However, the evolution mechanism of electrolytic gas products with multiple energy fields in laser-assisted electrolyte jet machining is not clear. In order to quantitatively characterize the laser-assisted facilitation of the evolution of electrolytic gas products, a gas quantification and detection device was designed and built in this paper. Compared to traditional electrolyte jet machining, laser-assisted electrolyte jet machining of 2024-T3 aluminum alloy increased the gas production by 52 % in 180 s. For the anode, the surface modification induced by laser texturing reduces the oxygen evolution potential and surface free energy and promotes gas nucleation and detachment. In addition, laser-induced conductive plasma can enhance transient currents for electrolyte jet machining and cause machining vibrations. The cathodic gas discharge phenomenon was characterized in conjunction with interelectrode gap visualization experiments and cathodic nozzle damage. Experimental results show that cathodic gas discharge depends on strong electric field and high laser pulse fluence. In summary, laser temperature rise, anode surface modification, laser-induced plasma, plasma recoil and cathode gas discharge can all contribute to the evolution of electrolytic gas products.

Optimization and characterization of boric acid powder mixed electrical discharge machining of Ti-6Al-4V ELI

The powder mixed electrical discharge machining (PMEDM) process is used for enhancing machining efficiency and improving the surface characteristics of the workpiece compared to normal EDM. The present study evaluates the effect of boric acid powder mixed in deionized water in PMEDM of Ti-6Al-4V ELI (extra low interstitial). The PMEDM process is assessed by evaluating material removal rate (MRR) and surface roughness (SR) at varying powder concentration (PC), current and pulse duration ( Ton). Boric acid PMEDM exhibits advantageous for both MRR and SR, where MRR increases and SR decreases with an increase in PC. To simultaneously achieve higher MRR and lower SR, the grey-fuzzy logic method is employed. Initially, the raw input data is normalized into grey numbers and a single index is obtained through grey relational analysis. Subsequently, triangular membership functions are assigned to the inputs and output. Fuzzy logic rules are then formulated, and grey fuzzy relational grade (GFRG) is calculated for each condition. The optimum condition (GFRG = 0.787) is attained at 15 g/l PC, 9 A current and 106 µs Ton, resulting in a 63% improvement compared to the initial condition. At the optimum condition, MRR increased by 145% and SR decreased by 29% compared to the initial condition. The effect of boric acid in PMEDM can be visualized through the formation of smooth surfaces, exhibiting reduced SR, smaller and shallower craters, and fewer debris and globules. Additionally, the boric acid PMEDM experiments resulted in the formation of a hard TiB phase on Ti-6Al-4V, thus improving its wear resistance.

Magnetic field assisted blasting erosion arc machining (M-BEAM): A novel efficient and quality improved machining method for Inconel 718

Electrical Arc Machining (EAM) presents an efficient technique for processing difficult-to-cut materials such as Inconel 718. However, despite its extremely high machining efficiency, the high energy density in machining makes it difficult to achieve a desirable surface quality that can be compatible with the subsequent cutting process. To solve this issue, this study explores the application of a magnetic field to enhance the performance of Blasting Erosion Arc Machining (BEAM), namely Magnetic Field assisted BEAM (M-BEAM). It leads to an increased Material Removal Rate (MRR) and reductions in both the Tool Wear Ratio (TWR) and the Surface Roughness (represented by Sa) with the increasing magnetic field strength, attributed to the improvements of the arc deflection and molten metal expelling. Moreover, the electromagnetic force is positively correlated with the discharge energy, which can further improve the machining performance of BEAM, especially when the hydrodynamic force is hard to act at large discharge energy. The MRR and Sa are enhanced and reduced by 14.52 % and 41.86 % respectively due to the stronger control effect at large energy. After multi-objective optimization, the optimized MRR in M-BEAM achieves a 9.22 % enhancement and Sa also decreases by 25.96 % and 60.61 % in the roughing and finishing process. This advancement also elevates machining precision as well as mitigates defects such as debris adhesion, overburning, and cracks. Moreover, the recast layer is significantly reduced by 88.59 % and 89.96 %. Consequently, M-BEAM promises extensive applications in aerospace industries for machining Inconel 718 and even for other difficult-to-cut materials with high efficiency and quality.

Use of RSM desirability approach to optimize WEDM of mild steel

Wire Electrical Discharge Machining (WEDM) is a non-traditional material removal process commonly used for precision machining of hard materials such as super alloys, ceramics, carbide, and composite materials. Optimization of process parameters is critical for improving machining efficiency and achieving the desired surface quality. Response Surface Methodology (RSM) systematically optimizes process parameters and investigates their impact on machining performance. WEDM control parameters such as pulse ON Time (TON) (50–60 μs), pulse OFF Time (TOFF) (25–34 μs), gap voltage (VG) (25–250 V), peak current (IP) (1–6 A), and dielectric flow rate (Df) (1–3 LPM) are optimized to reduce surface roughness (SR) and taper angle (TA) while increasing material removal rate (MRR) during the machining of Mild Steel. The optimal parameters are TON as 53 μs, TOFF as 28 μs, IP as 2.65 A, VG as 185 V, and Df as 1.5 LPM. The experimental findings are presented to demonstrate the usefulness of the proposed strategy in optimizing WEDM control parameters. The validation test was conducted under optimal conditions and the results were reported. The manufacturing industries can use RSM optimization in the manufacturing domain.

Achieving High Precision and Productivity in Laser Machining of Ti6Al4V Alloy: A Comprehensive Study using a n-predictor polynomial regression model and PSO algorithm

Ti-6Al-4V, the Titanium alloy, has significant utilizations in aerospace, automotive, and marine sectors for its low density and high strength at elevated temperature. But its chemical activity and low thermal conductivity inhibits its machining by conventional method. Nd: YAG laser beam machining (LBM) finds extensive use in rapid and precise cutting of Ti6Al4V. This study has examined the influences of various LBM machining variables, including laser power, gas pressure and stand-off distance, in cutting 5mm thick Ti-6Al-4V plate. In assessing the effectiveness and performance of the LBM process, three response functions—surface roughness, angle of kerf, and material removal rate—have been designated. From the experimental data, different regression models have been established to estimate these response functions in terms of the machining parameters. Based on R2 score and RMSE, multi-dimensional polynomial regression is decided as the most suitable regression model. Subsequently, the Particle Swarm Optimization technique has been applied to identify the optimal machining parameters for reducing angle of kerf and surface roughness, while increasing material removal rate. Three individual single-objective functions underwent optimization, along with a multi-objective function. Furthermore, experimental verification was conducted for the optimal input parameters in the single-objective as well as the multi-objective optimization scenarios, resulting in an accuracy of 97% and 98%, respectively. Such a close agreement emphasizes the accuracy of the developed regression model as well as it signifies the reliability and efficacy of the optimization technique.

Experimental investigations and process optimization of SKD61 for sinking EDM

ABSTRACT Electrical parameters are vital for electrical discharge machining (EDM) process performance. The study utilized the combination of Taguchi and grey relational analysis (GRA) to optimize sinking EDM. Optimization of peak current, pulse duration, duty ratio and electrode lifting time affecting material removal rate (MRR), relative electrode wear rate (REWR) and surface roughness (SR) in sinking EDM. Analysis of variance (ANOVA) shows that peak current and pulse duration significantly affect MRR and REWR, respectively. Peak current and pulse duration significantly affect SR. The optimized parameters were subjected to EDM experiments and the results are 8.54% increase in MRR, 11.11% decrease in REWR and 9.42% decrease in SR. It was found that at a peak current of 1A, the discharge pit not only depends on peak current and pulse duration but also on pulse off time. Compared to conventional optimization methods, this study analyzed the microstructure and recast layer of the workpieces.

Machinability and pulse characteristics of Ti-16Al-14Nb (α/β) alloy in wire-electric discharge machining process: A surface integrity study

The goal of the present work is to produce the efficient cutting of Ti-16Al-14Nb (α/β) alloy through wire-electric discharge machining and contemplate the terminologies such as machining ability, surface integrity and material removing capability. For this, the experimentation has been designed by considering three process parameters, pulse-on time ( Ton), pulse-off time ( Toff) and peak current ( Ip) at three significant levels (low, high, intermediate) in L27 order designed from design of experiments. The effect of these process variables on pulse characteristics, surface roughness ( Ra), kerfwidth ( Kw) and material removal rate ( MRR) is analyzed and mathematically modeled with analysis of variance. The results state that the highest MRR (0.521, 0.51, 0.506 mm3/sec) and low surface roughness (8.91, 8.89, 8.68 µm) values are observed at the highest level (110 µs, 15 µs, 8 A). If the pulse duration is kept at low ( Ton = 40µs, Toff = 3µs), the increase in peak current from 3 A to 8 A leads to a 64.54% increase in MRR and a 52.9% increase in Ra values. ANOVA results stated that Ton has contributed 20.4%, 35.8% and 19.3%, and Ip has contributed 43.1%, 30.5% and 46.6% influence on MRR, Kw and Ra respectively. The voltage–current characteristics studies confirmed that the strong intense pulses at a higher peak current (8 A) resulted in the increased MRR (0.521 mm3/sec) and Ra (8.43 µm) leading to the formation of swages and ridges. The surface integrity analysis derived from Abbott–Firestone curve agreed that the lowest level has shown better skewness ( Rsk = −0.274) and at highest level showed a larger deviation in skewness ( Rsk = +2.672) signifies that higher asymmetry (poor) of the surface.

PERFORMANCE ENHANCEMENT OF BRASS EDM ELECTRODES WITH CRYOGENIC TREATMENT WHILE MACHINING THE COLD WORK STEEL AISI D2

This study investigates the performance of deep cryogenically treated brass (CuZn25Al5) electrodes in the die-sink EDM process. Two different cryogenic treatment durations, 6 h and 12 h, were applied to 8 mm diameter electrodes, and their effects were compared to untreated electrodes. The machining tests were conducted under moderate and aggressive conditions. In the machining tests, the 6-h cryo-treated electrode exhibited a 16.8% increase in material removal rate (MRR) under moderate conditions and a 19.7% increase under aggressive conditions compared to the reference electrode. The 12-h cryo-treated electrode showed similar MRR values to the reference electrode but improved tool wear resistance by 9.4% under moderate conditions. The kerf angle was minimized, indicating better hole verticality, in the 6-h cryo-treated electrode group. The improvement in machining performance was attributed to the enhancement in electrical conductivity of the electrodes, which increased by 28% for the 6-h cryo-treated electrode and 20% for the 12-h cryo-treated electrode. X-ray diffraction (XRD) analysis revealed shifts in peak positions and possible phase transformations due to cryogenic treatment. Surface roughness measurements showed improved surface conditions in the cryo-treated electrodes under aggressive conditions. The results indicate that cryogenic treatment enhances MRR, reduces tool wear, and improves surface quality in die-sink EDM. These improvements are attributed to increased electrical conductivity and changes in the internal structure of the brass electrode.

Laser surface structuring of titanium alloy (Ti-6Al-4V) for improved tribocorrosion resistance for bio-implant applications

In this study, laser surface structuring (LSS) of titanium alloy (Ti-6Al-4 V) using pulsed Nd: YLF laser with 100 ns pulse duration at various laser powers, scan speeds, and line-spacings has been undertaken for improving the tribocorrosion property. Due to LSS, there is an increment in nano hardness (4.9 GPa - 6.3 GPa) and Young's modulus (140 GPa − 153 GPa) when compared to untreated Ti-6Al-4 V (3.9 GPa, 123 GPa). The tribocorrosion behavior in simulated body fluid against the ZrO2 ball in fretting mode shows that due to LSS, the degradation rate was significantly reduced (5.3–67.2%) when compared to the untreated one. With an increase in load, the coefficient of friction and material removal rate increases. The mechanism of tribocorrosion is established.

Influence of SiO2–ZnO mixed soft abrasive on tribological behavior and polishing performance of sapphire wafer

The use of reactive soft abrasives, capable of undergoing solid-state reactions with sapphire, is a promising approach for low-damage and low-contamination machining of sapphire wafers. This study calculates the Gibbs free energy change of these chemical reactions based on thermodynamic principles. SiO2–ZnO mixed soft abrasives were selected for the polishing of sapphire wafers. Friction and wear experiments were conducted to explore the tribological behavior of sapphire wafers with various mixed abrasives, leading to the optimization of the abrasive composition. The results show that mixed abrasives significantly enhance the material removal rate (MRR) of sapphire wafers. As the proportion of SiO2 in the mixture increases, the MRR correspondingly rises. Specifically, an SiO2–to–ZnO ratio of 2:1 in the mixed abrasives results in a 91.68% increase in MRR compared to using SiO2 abrasives alone. Based on these findings, five grinding discs with different abrasive ratios were prepared using a resin binder for mechanical–chemical polishing experiments on sapphire wafers. The polishing results corroborate those of the friction and wear experiments, confirming that an increased SiO2 content in the mixed abrasive discs leads to higher MRR. With a 2:1 ratio of SiO2 to ZnO in the mixed abrasive disc, the MRR is enhanced by 342.9% compared to discs with only SiO2 abrasives, while reducing the surface roughness to 3.21 nm. In the SiO2–ZnO mixed abrasives, the inclusion of ZnO enhances chemical reactions during polishing. Aided by the mechanical removal efficacy of SiO2, this approach significantly increases MRR while maintaining superior polishing quality.

Changing torque-force synchronization condition for abrasive particle improves material removal during silicon carbide abrasive machining

Silicon carbide (SiC) is extremely hard and brittle, posing challenges for traditional abrasive machining. This study used molecular dynamics simulations to investigate synchronous versus asynchronous force-torque effects on SiC abrasive machining. Multi-grit diamond abrasion of 4H-SiC was modeled by applying controlled sinusoidal forces and torques. Asynchronous force-torque increased material removal rates up to 2X versus synchronous conditions by promoting particle agglomeration and enabling trapped particles to contribute. However, asynchronous operation also produced higher surface roughness and subsurface cracking from greater penetration. The alternating forces generated larger stresses that may have driven more plastic deformation and brittle fracture. The study provided atomic-scale insights into force-torque effects, establishing guidelines to potentially enhance efficiency through asynchronous operation despite drawbacks.

A parametric study with experimental investigations of expanded graphite on performance measure of EDM process of Ni55.8Ti SMA

The present work focuses on the impact of expanded graphite (EG) nano-powder along with spark-on-duration (Ton) and spark-off-duration (Toff), and current as factors on increasing material removal rate (MRR), reduction of surface roughness (SR), tool wear rate (TWR), dimensional deviation (DD), and surface defects for Ni55.8Ti. Taguchi’s design having 4 factors at 3 levels was employed to perform the experimental trials. ANOVA has successfully validated the developed regression equations. EDM factors of PC, Toff, current, and Toff were found to be the largest contributing factors with the involvement of 76.91 %, 38.40 %, 34.36 %, and 44.54 % for MRR, TWR, SR, and DD respectively. TLBO algorithm was used in the present work to tackle the conflicting situation and to optimize the response variables. The simultaneous optimization conducted through the Teaching-learning-based optimization technique has yielded optimal parameters setting of Ton at 7 µs, Toff at 5 µs, PC at 1.5 g/L, and current at 10 A by giving optimal response values at MRR of 42.82 mm3/min, TWR of 0.4039 mm3/min, SR of 3.71 µm, and DD of 92.65 µm. Lastly, Scanning electron microscopy was utilized to check EG nano-powder significance on the machined parts' surface morphology.

Dispersion stabilization of carbonyl iron particles and its applications in chemical mechanical planarization

A novel aqueous magnetorheological (MR) slurry is proposed for potential application in the planarization of dielectric substrates, eliminating the need for traditional polishing pads. The preparation of a stable MR slurry hinges on the dispersion properties of abrasives and magnetic responsive particles, particularly high-density carbonyl iron particles (CIP). This study focuses on investigating the dispersion stabilities of CIP and its modified form, SiO2-coated CIP (SiO2@CIP), with the addition of ammonium polyacrylic acid (PAA-NH4) as a dispersant. Experimental measurements, including adsorption isotherms and zeta potential, combined with numerical simulations using density-functional theory, explore the adsorption behavior of PAA-NH4 on CIP and SiO2@CIP. Rheological and sedimentation analyses confirm PAA-NH4’s effectiveness in dispersing both particles. We elucidate the dispersion stabilization mechanism through calculations based on the Derjaguin−Landau−Verwey−Overbeek theory. In MR polishing, SiO2 coating on CIP improves efficiency, reducing surface roughness from over 8 nm (using CIP) to less than 8 Å (using SiO2@CIP). The addition of PAA-NH4 augments dispersion properties, leading to further enhancements in polishing efficiency, resulting in a surface roughness reduction to 2 Å and a simultaneous increase in material removal rate. We thoroughly examine the underlying factors driving these improvements.

Two material removal modes in chemical mechanical polishing: mechanical plowing vs. chemical bonding

AbstractWith the rapid development of semiconductors, the number of materials needed to be polished sharply increases. The material properties vary significantly, posing challenges to chemical mechanical polishing (CMP). Accordingly, the study aimed to classify the material removal mechanism. Based on the CMP and atomic force microscopy results, the six representative metals can be preliminarily classified into two groups, presumably due to different material removal modes. From the tribology perspective, the first group of Cu, Co, and Ni may mainly rely on the mechanical plowing effect. After adding H2O2, corrosion can be first enhanced and then suppressed, affecting the surface mechanical strength. Consequently, the material removal rate (MRR) and the surface roughness increase and decrease. By comparison, the second group of Ta, Ru, and Ti may primarily depend on the chemical bonding effect. Adding H2O2 can promote oxidation, increasing interfacial chemical bonds. Therefore, the MRR increases, and the surface roughness decreases and levels off. In addition, CMP can be regulated by tuning the synergistic effect of oxidation, complexation, and dissolution for mechanical plowing, while tuning the synergistic effect of oxidation and ionic strength for chemical bonding. The findings provide mechanistic insight into the material removal mechanism in CMP.

Development and experimental investigation of magnetic abrasive finishing of 17-4PH steel

Magnetic abrasive finishing (MAF) is a promising process for achieving better surface finish, not only on softer materials, but also on harder materials. In several industries, 17-4PH steel has predominantly being used due to its exceptional properties of better corrosion resistance, high strength-to-weight ratio, and ease of weldability. In this article, the details of a developed MAF attachment for a CNC vertical milling machine are presented. The developed attachment was used to finish the surface of 17-4PH steel and is suitable for plane workpiece surface. Effect of various MAF process parameters such as rotational speed of electromagnet, supply voltage/current, abrasive mesh number, and working gap were studied on 17-4PH steel for material removal rate (MRR) and percentage change in surface roughness (PCSR) using one-factor) using one-factor-at-a-time approach (OFAT). Based on experimental results, on increasing voltage/current, increase in MRR and PCSR was observed; however, decrease in PCSR and MRR was noticed with increase in the working gap. PCSR was increased up to 600 rpm of electromagnet and 600 mesh number. However, on further increase in speed and mesh number, resulted in decrease in PCSR. Supply voltage/current was the most significant input process parameter on PCSR for the constant values of others parameters. Maximum PCSR of 90.37% was observed at 1.5 mm working gap, 600 rpm rotational speed, 600 mesh number and 24 V/0.9A voltage/current. The results reported in the article are useful in identifying the relative significance of parameters for the selected workpiece material.

Nanoparticle Incorporation to Enhance Titanium Alloy Electric Discharge Machining Capabilities

The primary objective of this study was to examine the effects of the Powder-blended Micro Electric Discharge Machining (PMEDM) technique on micromachining applications, specifically when sea water is employed as the dielectric medium. Tiny apertures with a width of 200µm were punctured over Ti-6Al-4V plates. In the initial round of experimentation, the machining performance was evaluated by subjecting sea water to various process variables without the inclusion of any other ingredients. The effects of input variables, including electrode material, hole voltage, current, Pulse-on-time, and Duty factor, on the Material Removal Rate (MRR), Tool Wear Rate (TWR), Overcut (OC), Circularity Error (CE), and Taper Ratio (TR) were analysed by conducting tests in accordance with Taguchi's L18 plan design. The method employed to ascertain the optimal parametric configuration for multi-objective enhancement involved utilising the strategy of soliciting inclination based on similarity to an ideal arrangement. The present study aimed to investigate the effects of foreign materials on the dielectric-based miniature electrical discharge machining (EDM) process in sea water. This was achieved by utilising powders with varying weight concentrations and molecule sizes, including non-conductive (Al2O3), semi-conductive (SiC), and conductive (Al) powders. The experimental setup ensured that the variable boundaries were maintained at their ideal settings. The results indicate that the choice of tool has a notable influence on the functioning of micro EDM when sea water is employed as the dielectric, without the inclusion of extraneous particles. The performance metric of multi-objective execution in PMEDM is influenced by the conductivity of supplementary compounds. An 83.18 percent increase in Material Removal Rate (MRR) was observed when SiC added compounds were utilised in Powder Mixed Electrical Discharge Machining (PMEDM). Conversely, there was a drop in Tool Wear Rate (TWR) by 36.42 percent, Open Circuit voltage (OC) by 21.48 percent, Current Efficiency (CE) by 45.15 percent, and Tool Roughness (TR) by 22.87 percent.

Effect of input process parameters on MRR in micro EDM drilling of CFRP sheet using RSM

In recent years, composite materials are replaced most conventional (industrial) materials such as steel, aluminum, copper, etc. since, CFRP material is one of the most widely used composite materials due to its excellent mechanical as well as physical properties, including strength, modulus, and compressive strength. EDM micro-holes in CFRP composites present a challenge due to fiber orientation, uneven distribution of conducting fiber, and delamination, which affect material removal rate (MRR) and micro-hole quality. This article aims to optimize input process parameters for optimum MRR. Micro EDM input parameters such as voltage, capacitance, and electrode rotation speed are examined on the MRR of micro-holes by using response surface methodology. Experiments were conducted based on the Box-Behnken design of experiment. In the experiment, capacitance was found to be the most significant factor among all input process parameters affecting MRR. Regression equations and response surfaces are developed and the results are that capacitance and rotation speed of the electrode are increased initially, and the MRR increases, however, its value decreases as the capacitance and voltage are increased further. The optimum MRR is obtained in the range of 150–250 nF capacitance, at 100 V.

Enhancing Chemical Mechanical Polishing Efficiency of Steel with Sulfate

Excellent surface quality helps improve the tribological performance of gears. This study utilized chemical mechanical polishing (CMP) to process 18CrNiMo7–6 steel, a widely-used gear material. The results reveal that under the cooperative effect of oxidation and complexation, the material removal rate (MRR) can be significantly enhanced after adding K2SO4, while the surface roughness S a nearly remains unaltered. In particular, with 1 wt% H2O2 and citrate, the MRR increases by 251% after adding 100 mM K2SO4, while the S a slightly varies to 0.42 nm. No distinct surface defects are generated. For the mechanism, adding SO4 2− can promote iron corrosion and increase the amount of α-FeOOH. Citric acid can chelate α-FeOOH, forming complex compounds. The complex compounds and oxides form a relatively dense surface film, and thus the surface quality remains unchanged. In addition, the complex compounds may weaken the surface, and thereby the MRR increases. This study provides a simple approach for achieving high-efficiency CMP of steels.

Optimization of PMEDM process parameters for B4C and B4C+SiC reinforced AA7075 composites

MaterialsWith sufficient electrical conductivity can be successfully processed by applying the electrical discharge machining (EDM) method; however, due to the presence of non-conductive particles in composites, which have been produced by adding ceramics particles, problems such as unstable machining, low material removal rate, and high tool wear are observed during the EDM. This study employed powder-mixed electrical discharge machining (PMEDM) by adding electrically conductive nano-size graphite powder into the dielectric liquid to minimize these problems. Moreover, the machinability of AA7075/ B4C and AA7075/ B4C+SiC composites was evaluated using the Taguchi method. The experimental study used L18 orthogonal array (OA) (21 ×32). ANOVA was employed to obtain significant parameters and percent contributions of variable parameters on the material removal rate (MRR). Reinforcement ratio, current and sintering time applied to the workpiece were chosen as variable parameters. The optimum parameters for MRR were obtained at A1B3C3 (reinforcement ratio= 10%, current= 8 A, sintering time=150 min). According to S/N ratio graphs, increasing the reinforcement ratio leads to a decreased MRR. On the contrary, when the applied current increases, MRR increases. Additionally, analysis results show that the discharge current is the most important parameter affecting MRR. In the morphological examinations, it was understood that the amounts of B4C and SiC particles in the composite structure affect the quality of the machined surfaces. It was determined that the surface quality deteriorated with the increase in the amount of SiC and B4C in the composite structure and the increase in the discharge current.