Modelling and analysis of hybrid electrochemical turning-magnetic abrasive finishing of 6061 Al/Al2O3 composite

This paper integrates the electrochemical turning (ECT) process and magnetic abrasive finishing (MAF) to produce a combined process that improves the material removal rate (MRR) and reduces surface roughness (SR). The present study emphasizes the features of the development of comprehensive mathematical models based on response surface methodology (RSM) for correlating the interactive and higher-order influences of major machining parameters, i.e. magnetic flux density, applied voltage, tool feed rate and workpiece rotational speed on MRR and SR of 6061 Al/Al₂O₃ (10% wt) composite. The paper also highlights the various test results that also confirm the validity and correctness of the established mathematical models for in-depth analysis of the effects of hybrid ECT- MAF process parameters on metal removal rate and surface roughness. Further, optimal combination of these parameters has been evaluated and it can be used in order to maximize MRR and minimize SR. The results demonstrate that assisting ECT with MAF leads to an increase machining efficiency and resultant surface quality significantly, as compared to that achieved with the traditional ECT of some 147.6% and 33%, respectively.     

Modeling and analysis of the effects of machining parameters on the performance characteristics in the EDM process of Al2O3+TiC mixed ceramic

Electric discharge machining (EDM) has achieved remarkable success in the manufacture of conductive ceramic materials for the modern metal industry. Mathematical models are proposed for the modeling and analysis of the effects of machining parameters on the performance characteristics in the EDM process of Al₂O₃+TiC mixed ceramic which are developed using the response surface methodology (RSM) to explain the influences of four machining parameters (the discharge current, pulse on time, duty factor and open discharge voltage) on the performance characteristics of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The experiment plan adopts the centered central composite design (CCD). The separable influence of individual machining parameters and the interaction between these parameters are also investigated by using analysis of variance (ANOVA). This study highlights the development of mathematical models for investigating the influences of machining parameters on performance characteristics and the proposed mathematical models in this study have proven to fit and predict values of performance characteristics close to those readings recorded experimentally with a 95% confidence interval. Results show that the main two significant factors on the value of the material removal rate (MRR) are the discharge current and the duty factor. The discharge current and the pulse on time also have statistical significance on both the value of the electrode wear ratio (EWR) and the surface roughness (SR).     

Experimental modeling and optimization of electric discharge diamond face grinding of metal matrix composite

Machining of metal matrix composites (MMCs) has been a big challenge for manufacturing industries due to its superior mechanical properties. Unconventional machining methods have become an alternative to give desired shapes with intricate profiles and stringent design requirements. The present research investigates the grinding performance of copper–iron–graphite MMC using electric discharge diamond face grinding (EDDFG), which is electric discharge machining-based hybrid machining process. Experiments have been performed on a self-developed experimental setup of EDDFG with scientifically designed experiments. Effects of process input parameters on two important performances, material removal rate (MRR) and surface roughness (SR), have been analyzed. Genetic algorithm-based optimization of MRR and SR models show considerable improvements in both characteristics, as confirmed by verification experiments. Results reveal that peak current is a common significant factor for both MRR and SR.     

Study of electrochemical machining characteristics of Al/SiCp composites

Non-conventional machining is increasing in importance due to some of the specific advantages which can be exploited during machining operation. Electrochemical machining (ECM) appears to be a promising technique, since in many areas of application, it offers several special advantages including higher machining rate, better precision and control, and a wider range of materials that can be machined. The present work is, therefore, initiated to investigate the influence of some predominant electrochemical process parameters such as applied voltage, electrolyte concentration, electrolyte flow rate and tool feed rate on the metal removal rate (MRR), and surface roughness (Ra) to fulfill the effective utilization of electrochemical machining of LM25 Al/10%SiC composites produced through stir casting. The contour plots are generated to study the effect of process parameters as well as their interactions. The process parameters are optimized based on Response Surface Methodology (RSM).     

Enhancement of surface roughness in electrochemical machining of Ti6Al4V by pulsating electrolyte

Electrochemical machining (ECM) is widely used in machining a variety of components used in aerospace, defence, automotive and medical applications. The surface roughness of the ECM process has become important because of increased quality demands. Considerable attention has been paid to achieving low surface roughness in ECM. Surface roughness is closely related to the distribution of gases and Joule heat produced during the ECM process, which affect the electrolyte electric conductivity and directly determine the surface roughness. In this report, a pulsating electrolyte, which is one of the unsteady flows that are characterized by periodic fluctuations of the mass flow rate and pressure, is first introduced to the ECM process. The ECM process is affected by the pulsating electrolyte because it can modify the heat transfer. The goal of this report is to present experimental results of the surface roughness obtained on Ti6Al4V samples using a developed pulsating electrolyte supply system in ECM. It is observed that a lower surface roughness and higher material removal rate could be obtained by using a pulsating electrolyte with proper pulsating frequency and amplitude. In direct current ECM, the surface roughness Ra is 5.7 μm, the material removal rate is 0.85 g/min at a constant electrolyte, the lowest surface roughness is 3.69 μm and the largest material removal rate is 0.92 g/min, which are obtained at a pulsating frequency of 10 Hz and amplitude of 0.2 MPa. In pulsed current ECM, the surface roughness Ra and material removal rate are 0.67 μm and 0.38 g/min at a constant electrolyte, respectively, and both the minimum surface roughness Ra of 0.53 μm and maximum material removal rate of 0.39 g/min are observed when the proper pulsating electrolyte flow frequency and amplitude are used.     

Optimizing machining parameters of silicon carbide ceramics with ED milling and mechanical grinding combined process

A novel combined process of machining silicon carbide (SiC) ceramics with electrical discharge milling and mechanical grinding is presented. The process is able to effectively machine a large surface area on SiC ceramics with a good surface quality. The effect of tool polarity on the process performance has been investigated. The effects of peak current, peak voltage, pulse on-time and pulse off-time on the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR) have been investigated with Taguchi experimental design. The mathematical models for the MRR, EWR, and SR have been established with the stepwise regression method. The experiment results show that the MRR, EWR, and SR can reach 46.2543 mm³/min, 20.7176%, and 0.0340 µm, respectively, with each optimal combination level of machining parameters.     

Effect on crystalline structure of AISI M2 steel using tungsten–thorium electrode through MRR,EWR, and surface finish

To investigate on the crystalline structure of AISI M2 steel by using tungsten–thorium electrode in electrical discharge machining (EDM) process was studied. Furthermore, the investigation were carried out for finding the value of material removal rate (MRR), electrode wear rate (EWR) and surface roughness (SR) of tool steel material depending upon three variable input process parameters. On the basis of weight loss, the value of MRR and EWR were calculated at optimized process parameter. Subsequently, surface topography of the processed material were examined through different characterization techniques like scanning electron microscopy (SEM), Optical surface profiler (OSP) and Atomic force microscopy (AFM), respectively. In XRD study, broadening of the peak was observed which confirmed the change in material properties due to the homogeneous dispersion of the particles inside the matrix. Lowest surface roughness and MRR of 0.001208 mg/min was obtained. Minimum surface roughness was obtained 1.12 μm and 2.18427 nm by OSP and AFM study, respectively. Also, minimum EWR was found as 0.013986 mg/min.     

Experimental investigation on the electrochemical machining of 00Cr12Ni9Mo4Cu2 material and multi-objective parameters optimization

Special stainless steel 00Cr12Ni9Mo4Cu2 has multiple composition and inhomogeneous tissues; short circuiting will frequently occur when using conventional electrolyte processing. This article analyzes the reason why the process of machining is difficult from the material composition and structure. We used the NaNO₃ and NaClO₃ electrolyte composite to select the appropriate concentration, and then by using the orthogonal experiment and gray relational analysis method, we discussed how the voltage, feed speed, and electrolyte pressure solved the problem of the material removal rate (MRR), surface roughness (SR), and side gap. Under optimal conditions of 20 V, an electrolyte composite concentration of 178 g/l NaNO₃ and 41 g/l NaClO₃, a feed rate of 0.7 mm/min, and an electrolyte pressure of 0.8 MPa, a material removal rate of 100.8 mm3/min, a surface roughness of Ra 0.8 μm, and a side gap of 0.16 mm were produced. Given the same voltage, with an increasing cathode feed rate, the MRR was shown to increase while the surface roughness value and the side gap decreased. Under the same cathode feed rate, the MRR decreases, while the side gap and the surface roughness increase as the electrochemical machining application voltage increases. This study proves that using a certain concentration of electrolyte composite is a simple, low-cost, and feasible approach in improving efficiency and quality.     

The coupled effect of magnetic field,electric field,and electrolyte motion on the material removal amount in electrochemical machining

Electrochemical machining (ECM) has a strong advantage in dealing with difficult-to-machine materials and complex shaped parts. In order to improve machining accuracy, some researchers, based on the principle of interactions between the magnetic field and electric field, proposed the magnetic field-assisted ECM technology that is advantageous in improving surface roughness and facilitating material removal amount. Pitifully, little attention has been attached to effects of the coupled magnetic field, electric field, and electrolyte motion on the amount of materials removed. This paper aims to find out how arrangements of magnetic fields and coupled of the three energy (which were magnetic field, electric field, and electrolyte motion) will work on the amount of material removed in ECM. Here established a Navier-Stokes equation and a model of material removal amount in the anode under the electromagnetic field. Physical and mathematical models of the electrolyte’s flow characteristics and material removal amount were constructed through the COMSOL Multiphysics software, and simulations were carried out. An experiment was implemented to test models and the simulations. Simulation results indicated that different arrangements of the magnetic field had delivered different impacts on flow characteristics of the flow field and material removal amount. Experiment results revealed that the material removal amount had increased regardless of arrangements of magnetic fields and that the flow rate of the electrolyte had played a role in this connection. The study involved in this paper showed that the introduction of the magnetic field worked favorably to lift the material removal amount and that arrangements of magnetic fields also had the same effect in this regard. Also, it was found that a growing flow rate of the electrolyte had hindered the increases of the material removal amount.     

Investigation into electrochemical micromachining (EMM) through response surface methodology based approach

Electrochemical micromachining (EMM) could be used as one the best micromachining technique for machining electrically conducting, tough and difficult to machine material with appropriate machining parameters combination. This paper attempts to establish a comprehensive mathematical model for correlating the interactive and higher-order influences of various machining parameters, i.e. machining voltage pulse on/off ratio, machining voltage, electrolyte concentration, voltage frequency and tool vibration frequency on the predominant micromachining criteria, i.e. the material removal rate and the radial overcut through response surface methodology (RSM), utilizing relevant experimental data as obtained through experimentation. Validity and correctiveness of the developed mathematical models have also been tested through analysis of variance. Optimal combination of these predominant micromachining process parameters is obtained from these mathematical models for higher machining rate with acuuracy. Considering MRR and ROC simultaneously optimum values of predominant process parameters have been obtained as; pulse on/off ratio, 1.0, machining voltage, 3 V, electrolyte concentration, 15 g/l, voltage frequency of 42.118 Hz and tool vibration frequency as 300 Hz. The effects of various process parameters on the machining rate and radial overcut are also highlighted through different response surface graphs. Condition of machined micro-holes are also exhibited through the SEM micrographs in this paper. Pulse voltage pattern during electrochemical micromachining process has been analyzed with the help of voltage graphs. Irregularities in the nature of pulse voltage pattern during electrochemical micromachining have been observed and the causes of these irregularities are further investigated.     

Modelling of surface finish,electrode wear and material removal rate in electrical discharge machining of hard-to-machine alloys

Hard-to-machine alloys are commonly used for industrial applications in the aeronautical, nuclear and automotive sectors, where the materials must have excellent resistance to corrosion and oxidation, high temperature resistance and high mechanical strength. In this present study the influence of different parameters of the electrical discharge machining process on surface roughness, electrode wear and material removal rate have been studied. Regression techniques are employed to model arithmetic mean deviation Ra (μm), peak count Pc (1/cm), material removal rate MRR (mm³/min) and electrode wear EW (%). All these parameters have been studied in terms of current intensity supplied by the generator of the electrical discharge machine I (A), pulse time t_i (μs), duty cycle η and open-circuit voltage U (V). This modelling allows us to obtain mathematical data and models to predict that the most influential factor in MRR and Ra is the current intensity and in the case of EW and Pc is the pulse time.     

An experimental investigation on machining parameters of AISI D2 steel using WEDM

The performance of the wire electrodischarge machining (WEDM) machining process largely depends upon the selection of the appropriate machining variables. Optimization is one of the techniques used in manufacturing sectors to arrive for the best manufacturing conditions, which are essential for industries toward manufacturing of quality products at lowest cost. As there are many process variables involved in the WEDM machining process, it is difficult to choose a proper combination of these process variables in order to maximize material removal rate and to minimize tool wear and surface roughness. The objective of the this work is to investigate the effects of process variables like pulse on time, pulse off time, peak current, servo voltage, and wire feed on material removal rate (MRR), surface roughness (SR), gap voltage, gap current, and cutting rate in the WEDM machining process. The experiment has been done using Taguchi’s orthogonal array L27 (3⁵). Each experiment was conducted under different conditions of input parameters and statistically evaluated the experimental data by analysis of variance (ANOVA) using MINITAB and Design Expert tools. The present work also aims to develop mathematical models for correlating the inter-relationships of various WEDM machining parameters and performance parameters of machining on AISI D2 steel material using response surface methodology (RSM).The significant machining parameters and the optimal combination levels of machining parameters associated with performance parameters were also drawn. The observed optimal process parameter settings based on composite desirability (61.4 %) are pulse on time 112.66 μs, pulse off time 45 μs, spark gap voltage 46.95 V, wire feed 2 mm/min, peak current of 99.99 A for achieving maximum MRR, gap current, gap voltage, cutting rate, and minimum SR; finally, the results were experimentally verified.     

Parametric analysis on electrochemical discharge machining of silicon nitride ceramics

The electrochemical discharge machining (ECDM) process has a potential in the machining of silicon nitride ceramics. This paper describes the development of a second order, non-linear mathematical model for establishing the relationship among machining parameters, such as applied voltage, electrolyte concentration and inter-electrode gap, with the dominant machining process criteria, namely material removal rate (MRR), radial overcut (ROC) and thickness of heat affected zone (HAZ), during an ECDM operation on silicon nitride. The model is developed based on response surface methodology (RSM) using the relevant experimental data, which are obtained during an ECDM micro-drilling operation on silicon nitride ceramics. We also offer an analysis of variance (ANOVA) and a confirmation test to verify the fit and adequacy of the developed mathematical models. From the parametric analyses based on mathematical modelling, it can be recommended that applied voltage has more significant effects on MRR, ROC and HAZ thickness during ECDM micro-drilling operation as compared to other machining parameters such as electrolyte concentration and inter-electrode gap.     

Surface characteristics of ECMed titanium work samples for biomedical applications

Electrochemical machining (ECM) process has great potential on account of the versatility of its applications. ECM is being widely used in the manufacturing industry because hard metals can be machined regardless of the mechanical property of a work piece. Titanium is broadly used in a number of fields such as aerospace, power generation, automotive, chemical including petrochemical, and sporting goods. Apart from these applications, it has tremendous prospective in dental, medical industries, and biomedical engineering. The biological performance of titanium implant depends on their surface topography and form accuracy that includes various surface parameters. ECM is one of the alternative machining processes that can be applied to the machining of titanium implant for biomedical applications. The aim of this paper is to present experimental result of surface characteristics obtained on titanium samples, utilizing developed cross-flow electrolyte supply system in electrochemical machining. It is observed that electrolyte flow velocity and voltage between electrodes are some of the influencing parameters, which affect the surface characteristics. Titanium oxide layer has been generated on the machined surface, which facilitates the improvement of the corrosion and chemical resistance of titanium implant. Effects of electrolyte flow velocity and voltage during electrochemical machining process for generation of various surface characteristics have been successfully studied through experimentation. In the present work, the obtained surface roughness values on the titanium sample machined by ECM were in the range of 2.4 to 2.93???m, which is within acceptable value for the implants. Effects of electrolyte flow velocity and voltage on the material removal rate and machining accuracy in the form of overcut are also presented in the paper.     

A comparative experimental investigation of deep-hole micro-EDM drilling capability for cemented carbide (WC-Co) against austenitic stainless steel (SUS 304)

Microelectro-discharge machining (micro-EDM) has become a widely accepted non-traditional material removal process for machining difficult-to-cut but conductive materials effectively and economically. The present study aims to investigate the feasibility of machining deep microholes in two difficult-to-cut materials: cemented carbide (WC-Co) and austenitic stainless steel (SUS 304) using the micro-EDM drilling. The effect of discharge energy and electro-thermal material properties on the performance of the two work materials during the micro-EDM drilling has also been investigated. The micro-EDM drilling performance of two materials has been assessed based on the quality and accuracy of the produced microholes, machining stability, material removal rate (MRR), and electrode wear ratio. The results show that deep-hole micro-EDM drilling is technically more feasible in WC-Co as it offers microholes with smooth and burr-free surfaces at the rim in addition to improved circularity and lower overcut than those provided by SUS 304. Moreover, WC-Co exhibits better machinability during the deep-hole micro-EDM drilling, providing relatively higher MRR and stable machining.     

Influence of parameters and optimization of EDM performance measures on MDN 300 steel using Taguchi method

Maraging steel (MDN 300) exhibits high levels of strength and hardness. Optimization of performance measures is essential for effective machining. In this paper, Taguchi method, used to determine the influence of process parameters and optimization of electrical discharge machining (EDM) performance measures on MDN 300 steel, has been discussed. The process performance criteria such as material removal rate (MRR), tool wear rate (TWR), relative wear ratio (RWR), and surface roughness (SR) were evaluated. Discharge current, pulse on time, and pulse off time have been considered the main factors affecting EDM performance. The results of the present work reveal that the optimal level of the factors for SR and TWR are same but differs from the optimum levels of the factors for MRR and RWR. Further, discharge current, pulse on time, and pulse off time have been found to play a significant role in EDM operations. Detailed analysis of structural features of machined surface was done by using scanning electron microscope (SEM) to understand the influence of parameters. SEM of electrical discharge machining surface indicates that at higher discharge current and longer pulse on duration give rougher surface with more craters, globules of debris, pockmarks or chimneys, and microcracks than that of lower discharge current and lower pulse on duration.     

MACHINING OF SODA LIME GLASS USING ABRASIVE HOT AIR JET: AN EXPERIMENTAL STUDY

Abrasive Jet Machining is becoming one of the most prominent machining techniques for glass and other brittle materials. In this article, an attempt has been made to combine abrasive and hot air to form an abrasive hot air jet. Abrasive hot air jet machining can be applied to various operations such as drilling, surface etching, grooving and micro finishing on the glass and its composites. The effect of air temperature on the material removal rate applied to the process of glass etching and grooving is discussed in this article. The roughness of machined surface is also analyzed. It is found that the Material Removal Rate (MRR) increases as the temperature of carrier media (air) is increased. The results have revealed that the roughness of machined surface is reduced by increasing temperature of carrier media. The mechanism of material removal rate has been discussed with aid of SEM micrographs.     

Optimization of machining parameters for EDM operations based on central composite design and desirability approach

A novel aluminium metal matrix composite reinforced with SiC particles were prepared by liquid metallurgy route. Recent developments in composites are not only focused on the improvement of mechanical properties, but also on machinability for difficult-to-machine shapes. Electrical discharge machining (EDM) was employed to machine MMC with copper electrode. using EDM. Experiments were conducted using pulse current, gap voltage, pulse on time and pulse off time as typical process parameters. The experiment plan adopts face centered central composite design of response surface methodology. Analysis of variance was applied to investigate the influence of process parameters and their interactions viz., pulse current, gap voltage, pulse on time and pulse off time on material removal rate (MRR), electrode wear ratio (EWR) and surface roughness (SR). The objective was to identify the significant process parameters that affect the output characteristics. Further a mathematical model has been formulated by applying response surface method in order to estimate the machining characteristics such as MRR, EWR and SR.     

Grinding-aided electrochemical discharge machining of particulate reinforced metal matrix composites

A grinding-aided electrochemical discharge machining (G-ECDM) process has been developed to improve the performance of the conventional ECDM process in machining particulate reinforced metal matrix composites (MMCs). The G-ECDM process functions under a combined action of electrochemical dissolution, spark erosion, and direct mechanical grinding. The tool electrode has a coating containing a hard reinforcement phase of diamond particles. The MMC employed in this study was Al₂O₃ particulate reinforced aluminum 6061 alloy. The material removal mechanism of this hybrid process has been analyzed. The results showed that the grinding action can effectively remove re-cast material deposited on the machining surface. The surface roughness (R _a) measured for the G-ECDM specimen was ten times smaller than that of the specimen machined without grinding aid (i.e., ECDM alone). Moreover, the material removal rate (MRR) of G-ECDM was about three times higher than that of ECDM under the experimental conditions of this study. The voltage waveform and crater distribution were also analyzed, and the experimental results showed that the G-ECDM process operates in a stable condition. The relative importance of the various processing parameters on MRR was established using orthogonal analysis. The results showed that MRR is influenced by the machining parameters in the order of duty cycle?>?current?>?electrolyte concentration. This study showed that the G-ECDM process is superior to the ECDM process for machining particulate reinforced MMCs, where a higher machining efficiency and a better surface quality can be obtained.     

Drilling of micro-holes on copper using electrochemical micromachining

Electrochemical micromachining (EMM) is one of the best micromachining techniques for machining electrically conducting, tough, and difficult-to-machine materials with suitable machining parameter combinations. For the micro-fabrication of components like nozzle plate for ink jet printer head and delicate 3D electronic circuit board components, EMM is predominantly used. In this paper, the effect of process parameters such as such as electrolyte concentration, machining voltage, frequency, and duty cycle on the material removal rate (MRR) and overcut were studied using copper workpiece. According to Taguchi’s quality design concepts, an L₁₈ orthogonal array is used. ANOVA is also performed to determine the most significant parameter that influences the EMM process. The optimum process parameters for lower overcut and higher MRR are found out and confirmation tests were carried out to validate the prediction. The confirmation test results show 19 and 20.78?% improvements of overcut and MRR, respectively, with respect to the initial parametric setting.