WEDM of Mg/CRT/BN composites: Effect of materials and machining parameters

The current work presents a detailed exploration on real-time wire electric discharge machining (WEDM) experiments and grey relational analysis (GRA)–based multi-criteria optimization of material and machining characteristics for lowered surface roughness (R_a) and improvised material removal rate (MRR) of the newly developed magnesium/boron nitride/cathode ray tube (Mg/BN/CRT) hybrid metal matrix composites (MMCs). The composites were fabricated through powder metallurgy (PM) route by reinforcing silica-rich E-waste CRT panel glass powder crushed for different particle sizes (10, 30, and 50?µm) at various weight percentages (5%, 10%, and 15%) and with 2% boron nitride (BN). Taguchi-based orthogonal array procedure was utilized to formulate the experimental plan for WEDM considering reinforcement level and size, pulse on time (P_on), pulse off time (P_off), and wire feed (W_f) as the input process parameters. ANOVA results reveal that P_on and wt% of reinforcement has more effect on R_a and MRR than any other considered parameters. The developed mathematical model for R_a and MRR predicted values similar to that of experimental results. Multi-criteria optimization was done through GRA technique and the so recommended optimum parameter set furnishes higher MRR (22.34?mm³/min) and reduced R_a (2.87?µm).     

Experimental investigations into electric discharge grinding and ultrasonic vibration-assisted electric discharge grinding of Inconel 601

The paper presents experimental investigations into electric discharge grinding (EDG) and ultrasonic vibration-assisted electric discharge grinding (UVAEDG) of Inconel 601. The process parameters selected for both processes were duty cycle, discharge current, pulse on time, grinding wheel speed, work speed, and speed ratio to study their influence on responses like surface roughness (R_a) and material removal rate (MRR). It was found that duty cycle, wheel speed, work speed, discharge current, speed ratio, and pulse duration significantly influenced MRR and R_a. It was inferred that MRR increased with increase in duty cycle, wheel speed, current, work speed, and pulse duration in both EDG and UVAEDG processes. It was also inferred that R_a increased with rise in duty factor, pulse on time, and discharge current in EDG and UVAEDG processes.     

Influence of input parameters on the near-dry WEDM of Monel alloy

Near-dry wire electrical discharge machining (WEDM) is a modified WEDM process, which has no adverse effects on the environment, in which metal removals have been done with the dielectric medium being used in the form of a mist. As the increase in production by reducing the machining time is a costly affair, the input parameters attract considerable attention for their optimization. The predominant control characteristics in this study are the time-bound material removal and surface quality. The time duration of the electrical pulse on and off, wire feed, air inlet pressure, and water flow rate are the parameters considered for this experimental analysis. In this paper, the optimization techniques such as RSM method and analysis of variance (ANOVA) were used to route the experiments and optimize the responses of near-dry WEDM process for machining the material Monel alloy. A model has been formulated mathematically for the two vital responses needed, under the influence of regression analysis. Additivity test has been performed to validate the mathematical model. The air–water mixture in the form of a mist was used in place of dielectric medium to study the impact on material removal rate (MRR), surface roughness (R_a), and environment. It was observed that a high surface finish could be obtained at 3 bar pressure.     

Effect of deep cryotreated tungsten carbide electrode and SiC powder on EDM performance of AISI 304

Abstract

Powder mixed electric discharge machining (PMEDM) is a further advancement of conventional EDM process in which electrically conductive powder is suspended in the dielectric fluid to enhance the material removal rate (MRR) along with the surface quality. Cryotreatment is introduced in this process for improving the cutting tool properties as well as tool life. In this investigation, EDM is performed for the machining of AISI 304 stainless steel using cryotreated double tempered tungsten carbide electrode when SiC powder is suspended in the kerosene dielectric. The influence of process parameters viz. pulse on time, peak current, duty cycle, gap voltage and powder concentration on tool wear rate (TWR), surface roughness (R_a), and MRR has been studied. Metallographic analysis was carried out for the machined surfaces. By the addition of powder concentration and cryotreated double tempered electrode, significant improvement in the machining efficiency has been found out. When cryotreated electrode used MRR, TWR and R_a decreased by 12%, 24% and 13.3%, respectively and when SiC powder used MRR increased by 23.2%, TWR and R_a decreased by about 25% and 14.2%, respectively.     

Synergetic effects of pulse constraints and additives in electrodeposition of nanocrystalline zinc: Corrosion,structural and textural characterization

Pulse electrodeposition was to produce nanocrystalline (nc) zinc from alkaline non-cyanide electrolyte with primary and secondary additives. The combined effect of pulse parameters (ON-time (T_ON), OFF-time (T_OFF), pulse peak current density (I_P)) and additives on the corrosion properties (evaluated using electrochemical techniques) of zinc electrodeposits are elucidated in terms of surface morphology (using scanning electron microscope), topography and root mean square (RMS) roughness (using atomic force microscope), crystallite size, its orientations and relative texture co-efficient (RTC, %) were evaluated using X-ray diffraction. The corrosion resistance of zinc electrodeposits obtained at constant T_ON and I_P enhanced (i.e., low I_corr and high R_ct values) with increased T_OFF. At constant T_OFF and I_P, the I_corr values increased and R_ct values decreased with T_ON while the former decreases and latter increases with I_P at constant T_ON and T_OFF. The inclusion of primary and secondary additives into the electrolyte produced nc zinc electrodeposits at 5 Adm^?2, showed enhanced protective properties (I_corr—16 μA cm^?2 and R_ct—481.8 Ω cm^?2). Fine grained due to high negative overpotential, reduced roughness and higher percentage of basal plane [0 0. 2] orientation have major impact for the enhanced corrosion resistances.     

Influence of materials and machining parameters on WEDM of Al/AlCoCrFeNiMo0.5 MMC

The current study intends to optimize the wire electric discharge machining (WEDM) parameters while machining the newer AlCoCrFeNiMo_0.5 high entropy alloy (HEA) particles-reinforced aluminum composites. AlCoCrFeNiMo_0.5 HEA particles produced through arc melting technique are reinforced here for different weight % (0%, 3%, 6%, 9%, 12%, and 15%) along with pure aluminum by the way of powder metallurgy. WEDM studies were conducted by varying the appropriate parameters, namely, pulse ON time, pulse OFF time, and wire feed. Based on the selected parameters, through Taguchi method L18 orthogonal array is designed; the optimal parameter combination for better surface finish, material removal rate (MRR), and reduced kerf width (KW) is identified. For better understanding, through ANOVA, also the effect of each input variables over these adopted response variables was analyzed. The yielded results reveal that addition of AlCoCrFeNiMo_0.5 HEA as reinforcement has considerable effect over the response variablessuch that MRR and KW reduces; surface roughness increases with increase in HEA %. ANOVA results confirm that pulse ON time has higher effect over the response variables than any other parameters involved for the study. Multi-objective optimization done through Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) methodology answers that MRR and surface finish have improved, whereas KW gets reduced noticeably.     

Multi-attribute decision-making of cryogenically cooled micro-EDM drilling process parameters using TOPSIS method

The geometrical characteristics of the micro-holes along with the performance measures are matter of critical concern in micro-electrical discharge machining (μEDM) process. This paper presents the multi-attribute decision-making of cryogenically cooled micro-EDM (CμEDM) drilling process. Current (I_p), pulse on duration (T_on), pulse off duration (T_off), and gap voltage (V_g) were the input process parameters preferred to optimize the multiple responses of geometrical characterization including taper angle (TA), overcut (OC), circularity at the entry and exit (C_ent and C_exit), and performance measures including material removal rate (MRR), tool wear rate (TWR), and average roughness (R_a). The Taguchi-based L₂₇ orthogonal array (OA) is used to carry out the experimental runs, and technique for order of preference by similarity ideal solution (TOPSIS) approach is used for the identification of optimal parameters on AISI 304 stainless steel. The optimized result achieved from this approach suggests improved TA, OC, C_ent, C_exit, MRR, and lower TWR, surface roughness (SR) with the combinations of CμEDM drilling process such as I_p of 15 A, T_on of 10?µs, T_off of 30?µs, and V_g of 30?V. Analysis of variance (ANOVA) was conducted to identify the major influencing parameter.     

Controlling the material removal and roughness of Inconel 718 in laser machining

Nickel alloys including Inconel 718 are considered as challenging materials for machining. Laser beam machining could be a promising choice to deal with such materials for simple to complex machining features. The machining accuracy is mainly dependent on the rate of material removal per laser scan. Because of the involvement of many laser parameters and complexity of the machining mechanism it is not always simple to achieve machining with desired accuracy. Actual machining depth extremely varies from very low to aggressively high values with reference to the designed depth. Thus, a research is needed to be carried out to control the process parameters to get actual material removal rate (MRR_act) equals to the theoretical material removal rate (MRR_th) with minimum surface roughness (SR) of the machined surfaces. In this study, five important laser parameters have been used to investigate their effects on MRR and SR. Statistical analysis are performed to identify the significant parameters with their strength of effects. Mathematical models have been developed and validated to predict the machining responses. Optimal set of laser parameters have also been proposed and confirmed to achieve the actual MRR close to the designed MRR (MRR_% = 100.1%) with minimum surface roughness (R_a = 2.67 µm).     

Effects of process parameters on fatigue behavior and surface integrity of tool steel produced by electrical discharge turning

Electrical discharge machining is used in the production of countless parts with complex geometries and micro dimensions, from many elements of industrial molds to parts of motors and pumps. Also, most of these parts are cylindrical and it is always more meaningful to study their rotational fatigue behavior to predict their response during their operation. This study concentrated on the impacts of machining parameters on the surface quality and fatigue behavior of tool steel shaped by electrical discharge turning. The results based on Taguchi methodology have shown that discharge current affects R_a and R_z more, and pulse duration more affects the mean spacing of profile irregularities, S_m. As a result of the heat affected depth in the machined region, which changes in proportional with the processing parameters, the microhardness decreased from the sample surface to the core. The maximum hardness was measured at current of 12 A, pulse duration of 3 μs and pulse interval of 7 μs. According to the fatigue tests, it was found that the fatigue life decreased with the increase in R_z and S_m values. Moreover, high microhardness and thick recast layer reduced the fatigue strength of the samples with relatively smooth surface topography.     

Optimization of photochemical machining process parameters for manufacturing microfluidic channel

In the present study, the investigation on photochemical machining (PCM) of stainless steel (SS-304) by ferric chloride as etchant is reported. SS-304 is machined by PCM process to obtain accurate dimensions and better geometrical features. Weighted grey relational analysis (WGRA) technique is used in optimization of PCM process parameters. DoE (L₂₇) orthogonal array is applied to evaluate machining parameters, such as concentration of etchant, etching time, and temperature of etchant. The multiobjective optimization technique is used to optimize material removal rate (MRR), surface roughness (R_a), undercut (U_c) and etch factor (EF). Weighted grey relational grade is calculated to minimize U_c and surface roughness and to maximize MRR and EF. The quality characteristics MRR, EF, U_c, and R_a are reporting the improvement after the confirmatory test. The optimum machining parameters are processed to manufacture the microfluidic channel used in biomedical applications. The microfluidic channels and its assembly with Y-type for mixing of fluid with a size of 100 µm, 200 µm, and 300 µm are developed and investigated.     

Experimental Investigation and Optimization of Process Parameters of Al/SiC MMCs Finished by Abrasive Flow Machining

In the era of nontraditional finishing processes, it is of upmost importance that these processes can be applied to composite materials as these have replaced traditional materials in many applications. Abrasive Flow Machining (AFM) is an advanced finishing process. Composite materials have replaced traditional materials as their properties such as light weight, high strength, and good economy are of great benefit. In the literature, work has been reported on AFM of materials such as aluminum, brass, and EN8. In the present work, composite materials with a high percentage of SiC (e.g., 20–60% SiC in Al/SiC composites) were machined using abrasive flow finishing. The Taguchi method was applied to find the effect of input parameters on material removal rate (MRR), change in surface roughness (ΔR_a), and surface topography, and L27 array was designed for experimentation. It was observed that extrusion pressure is the most significant factor in regard to MRR and ΔR_a. Optimization of response parameters (MRR and ΔR_a) was determined using the Taguchi method. Microstructure analysis was also done for workpiece materials using SEM and XRD.     

Improving the machining performance characteristics of the µEDM drilling process by the online cryogenic cooling approach

Productivity and surface quality would significantly affect the performance of the micro electrical discharge machining process (µEDM). Thus, the machining performance would be enhanced by improving the material removal rate (MRR) and surface quality. In this investigation, cryogenic LN₂ cooling was introduced to the conventional µEDM setup for developing an innovative process of cryogenically cooled µEDM process (CµEDM). The favorable outcomes of this process were estimated by selecting discharge current (I_p) and pulse on duration (T_on) for determining the effects of the machining performance including MRR and surface integrity. Surface quality was also analyzed by microstructural analysis and a scanning electron microscope (SEM) for evaluating the effects of the cryogenically cooled µEDM process. The experimental result shows 54–62% improvement in MRR and 22–36% improvement in average roughness values. Hence, it is suggested that cryogenically cooled µEDM facilitates improvement in productivity and surface quality.     

Machining Parameters Optimization of Titanium Alloy using Response Surface Methodology and Particle Swarm Optimization under Minimum-Quantity Lubrication Environment

The present paper depicts an application of response surface methodology (RSM) and particle swarm optimization (PSO) technique for optimizing the machining factors in turning of titanium (Grade-II) alloy using cubic boron nitride insert tool under minimum quantity lubricant (MQL) environment. The three machining factors, i.e., cutting speed (V_c), feed rate (f) and side cutting edge angle (approach angle π), are designed as three factors by using RSM design, which is withal subject to several constraints including tangential force (F_c), tool wear (V_Bmax), surface roughness (R_a) and tool-chip contact length (L). The multiple regression technique was used to establish the interaction between input parameters and given responses. Moreover, the results have been presented and optimized process parameters are acquired through multi-response optimization via desirability function as well as the PSO technique. The lower values of V_c (200 m/min), f (0.10 mm/rev) and higher values of ? (90°) are the optimum machining factors for minimizing the aforementioned responses. It was also observed that the selected responses predicated on PSO are much closer as that of the values acquired in view of the desirability function approach. Henceforth, PSO has the potential to cull appropriate machining factors while turning titanium (Grade-II) alloys under MQL conditions.     

Investigating Feasibility Through Performance Analysis of Green Dielectrics for Sustainable Electric Discharge Machining

This work represents a feasibility study for the newly proposed vegetable oil-based green dielectric fluids, biodielectric1 (BD1) and biodielectric2 (BD2) for electric discharge machining (EDM). Comparative analyses for BD1, BD2, and kerosene have been studied to assess the performance in terms of material removal rate (MRR), electrode wear rate (EWR), and relative wear ratio (RWR) for P20 + cold-worked plastic injection mold steel using electrolytic grade copper electrode. Current, gap voltage, pulse on time (T_on), and pulse off time (T_off) have been chosen as input parameters, and one variable at a time approach has been used for designing experimental plan for investigating the feasibility of the newly suggested fluids. The results obtained show that the performance of the newly suggested biodielectrics BD1 and BD2 is better than commercially used hydrocarbon-based dielectric, i.e., kerosene, for MRR and RWR. Analysis of variance results indicated that current is the most influencing parameter for MRR and EWR, while T_on is the most significant parameter for RWR. Under the influence of current, BD1 and BD2 produced 38% and 165% improvement in MRR, respectively. Moreover, BD1 and BD2 resulted 30% higher and 7% lower RWR, respectively, under the influence of T_on.     

Modeling and Analysis of Machinability Evaluation in the Wire Electrical Discharge Machining (WEDM) Process of Aluminum Oxide-Based Ceramic

The wire electrical discharge machining (WEDM) allowed success in the manufacture of the hard, fragile, and materials difficult to cut, especially for electroconductive ceramic materials. In this study, the mathematical models of material removal rate (MRR) and surface roughness (SR) used for the machinability evaluation in the WEDM process of aluminum oxide-based ceramic material (Al₂O₃ + TiC) have been carried out. The experimental plan adopts the face centered central composite design (CCD). The mathematical models using the response surface methodology (RSM) are developed so as to investigate the influences of four machining parameters, including the peak current, pulse on time, duty factor, and wire speed, on the performance characteristics of MRR and SR. It has been proved that the proposed mathematical models in this study would fit and predict values of the performance characteristics, which would be close to the readings recorded in experiment with a 95% confidence level. The significant parameters that critically affect the performance characteristics are examined.     

AWJM Performance of jute/polyester composite using MOORA and analytical models

This work addresses the machinability performance of jute/polyester composites with variable laminate thickness using Abrasive water jet machining (AWJM) process. A hybrid objective function was developed using surface roughness (R_a) and kerf taper angle (T_a) and studied using a cost-effective Multi Objective Optimization by Ratio Analysis named as MOORA. The influence of machining parameters such as hydraulic pressure (P), feed rate (V_f) and standoff distance (S_d) on quality characteristics were considered for this analysis. Among all, V_f was found to be a strong influencing factor on T_a and R_a. The deviation in the magnitude of T_a and R_a was observed in the case of varying laminate thicknesses without affecting the optimum condition. Besides, a mathematical regression model was developed for both T_a and R_a based on the correlation between the dependent variables. Furthermore, two other models of R_a available in the literature were considered for comparison with experimental results. The results revealed the suitability of these models for the polymer-based fiber-reinforced composite materials, but limited to the maximum thickness of 3?mm. The good agreement of the models with two different sets of experimental values was also found.     

Electrochemical Tantalum Oxide for Resistive Switching Memories

Redox‐based resistive switching memories (ReRAMs) are strongest candidates for the next‐generation nonvolatile memories fulfilling the criteria for fast, energy efficient, and scalable green IT. These types of devices can also be used for selector elements, alternative logic circuits and computing, and memristive and neuromorphic operations. ReRAMs are composed of metal/solid electrolyte/metal junctions in which the solid electrolyte is typically a metal oxide or multilayer oxides structures. Here, this study offers an effective and cheap electrochemical approach to fabricate Ta/Ta₂O₅‐based devices by anodizing. This method allows to grow high‐quality and dense oxide thin films onto a metallic substrates with precise control over morphology and thickness. Electrochemical‐oxide‐based devices demonstrate superior properties, i.e., endurance of at least 10⁶ pulse cycles and/or 10³I–V sweeps maintaining a good memory window with a low dispersion in R_OFF and R_ON values, nanosecond fast switching, and data retention of at least 10⁴ s. Multilevel programing capability is presented with both I–V sweeps and pulse measurements. Thus, it is shown that anodizing has a great prospective as a method for preparation of dense oxide films for resistive switching memories.     

Integrated ANN–GA for estimating the minimum value for machining performance

In this study, we proposed a new approach in estimating a minimum value of machining performance. In this approach, artificial neural network (ANN) and genetic algorithm (GA) techniques were integrated in order to search for a set of optimal cutting condition points that leads to the minimum value of machining performance. Three machining cutting conditions for end milling operation that were considered in this study are speed (v), feed (f) and radial rake angle (γ). The considered machining performance is surface roughness (R _a). The minimum R _a value at the optimal v, f and γ points was expected from this approach. Using the proposed approach, named integrated ANN–GA, this study has proven that R _a can be estimated to be 0.139?µm, at the optimal cutting conditions of f?=?167.029?m/min, v?=?0.025?mm/tooth and γ?=?14.769°. Consequently, the ANN–GA integration system has reduced the R _a value at about 26.8%, 25.7%, 26.1% and 49.8%, compared to the experimental, regression, ANN and response surface method results, respectively. Compared to the conventional GA result, it was also found that integrated ANN–GA reduced the mean R _a value and the number of iterations in searching for the optimal result at about 0.61% and 23.9%, respectively.     

Resistive switching of HfO2-based Metal-Insulator-Metal diodes: Impact of the top electrode material

This paper deals with the impact of the top metal electrode on the resistive switching properties of HfO₂-based Metal-Insulator-Metal diodes. By screening five different metals as top electrode, Al-Cu-Hf-Pt-Ti, we have demonstrated the feasibility of the resistive switching effect on HfO₂. Metals with a low enthalpy of formation of oxides ΔH_f⁰ (Pt and Cu) lead to uni-polar switching whereas easily oxidizable metals with a higher ΔH_f⁰ (Al, Hf and Ti) lead to bipolar switching. Cu-, Hf- and Pt-based devices show a degradation of the top electrode after the forming step by the formation of bubbles whereas such phenomenon was not observed in Al- and Ti-based devices. 200 switching cycles were performed on each device in order to extract the main parameters of the resistive switching effect: I_ON and I_OFF currents in the mA range, R_OFF/R_ON resistance ratio up to 5, V_set and V_reset, voltage levels around 1 V, and powers dissipated during read and write operations in the μW and mW range, respectively. For all systems, the reset process dissipates higher power than the set process. From these results, the Ti top adlayer shows the best performance in terms of stability and resistive switching characteristics.     

Investigation on performance of abrasive water jet in machining hybrid composites

For machining of composites, abrasive water jet machining is widely employed. For assembly of the machine tool structure, production of slots is essential. In this paper, abrasive water jet machining of composite laminates was experimentally investigated for various cutting parameters in terms of average surface roughness (R_a) and kerf taper (K_t). By generating a response surface model, the experimental values obtained for quality characteristics (R_a and K_t) were empirically related to cutting parameters. The effects of cutting parameters on quality characteristics were analyzed by utilizing empirical models and also optimized within the tested range based on desirability approach. The optimum parameter levels were also validated by confirmation test. From this investigation, it is evident that for obtaining a minimum kerf taper, traverse speed, water pressure, and abrasive mass flow rate are significant parameters and for obtaining less surface roughness traverse speed is the significant parameter.