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.     

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.     

Evaluation of WEDM performance characteristics of Inconel 706 for turbine disk application

Inconel 706 is a newly developed superalloy, which offers high mechanical strength alongwith easy fabricability thus making it suitable for turbine disk applications. Although Inconel 706 exhibits a substantial increase in stress rupture and tensile yield strength compared to other superalloys, its conventional machining yields poor surface finish and low dimensional accuracy of the machined components. Hence, wire electrical discharge machining (WEDM) of Inconel 706 has been performed and various performance attributes such as material removal rate (MRR), surface roughness (SR), recast surface, topography, microhardness, microstructural and metallurgical changes of the machined components have been evaluated. The experimental results revealed that servo voltage, pulse on time, and pulse off time greatly influence the MRR and SR. Due to high toughness of Inconel 706, no micro cracks were observed on the machined surface. Micro voids and micro globules are significantly reduced at low pulse on time and high servo voltage. But, there is a propensity of thick recast layer formation at high pulse on time and low servo voltage. EDAX analysis of recast surface exposed the existence of Cu and Zn which have migrated from the brass wire. The subsurface microhardness was changed to 80 μm due to significant thermal degradation.     

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).     

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).     

Investigation of magnetic field-assisted EDM of composites

The Electrical Discharge Machining (EDM) technique was performed under the magnetic field influence to determine the material removal mechanism as well as surface roughness (SR) of nonmagnetic material. This study presents an exploration of the hybrid EDM technique assisted by magnetic field, with an aim to improve process performance. Herein, magnetic field intensity, peak current, duration of pulse-on/off, tool electrode material, and SiC percentage distribution were opted as the machining parameters. The chosen parameters were analyzed for their effects on the material removal rate (MRR) and SR while machining of SiC-reinforced aluminum-based metal matrix composites. Taguchi methodology was adopted for optimization of process parameters to achieve better MRR and lower SR. The experimental results witnessed improved surface finish and enhanced material removal ability of the process and also inferred that the magnetic field-assisted EDM facilitated the process stability.     

Characteristics of wire-electro discharge machined Ti6Al4V surface

Titanium and titanium alloys (e.g., Ti6Al4V) are increasingly used in aerospace and automotive industries, and also used as medical implant material in wide variety of applications. Wire-electro discharge machining (WEDM) is an important non-traditional machining process, widely used for machining a variety of difficult-to-machine materials including titanium alloys with intricate shapes. The process is essentially a thermal process and the nature of surface produced is studied in this paper. It is observed that more uniform surface characteristics are obtained with coated wire electrode. Among the parameters such as time between two pulses, pulse duration, injection pressure, wire speed and wire tension that have more influence on the surface characteristics, the time between two pulses is the most sensitive parameter.     

WEDM process parameter optimization of FSPed copper-BN composites

A systematic view on evaluating the machining characteristics of Wire Cut Electrical Discharge Machining (WEDM) employing Taguchi Method and Grey Relational Analysis based multiobjective optimization is provided in this research article. The outcome of various WEDM processing parameters including pulse discharge on time (Pulse_ON), pulse discharge off time (Pulse_OFF), wire feed rate (Wire_FR) along with the material characteristics of varying Boron Nitride (BN) volume fractions while machining a friction stir processed (FSPed) copper-BN surface composite was investigated. The output responses considered in this research include Material Removal Rate (MRR) and Surface roughness (R_a) that was obtained from the L27 orthogonal array based on the above said input factors. ANOVA was performed, and Pulse_ON and BN volume fraction were found most significant for MRR, while Pulse_ON and Pulse_OFF influence the most in attaining minimal R_a values. Based on the obtained experimental values for MRR and R_a, a mathematical model was developed based on the control factors and was proved to be precise in predicting the output response. An optimal combination of input control factors was finalized through grey relational analysis, and the same proved to achieve the utmost MRR (20.19?mm³/min) and nominal R_a(3.01?µs) values.     

Performance evaluation of cryogenically assisted electric discharge machining (CEDM) process

The performance of cryogenically assisted electric discharge machining (CEDM) process has been evaluated in the presented research paper. The machining of cryogenically treated (CT) and cryogenically untreated (CUT) AISI D2 tool steel work specimens using cryogenically cooled (CC), CT, and CUT copper electrodes have been performed. The effects of various parameters, namely, workpiece condition, tool condition, nozzle flushing, peak current, duty cycle, pulse duration, and gap voltage, have been studied on the performance indicators, viz. the material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR). The best parametric combinations have been suggested to obtain the desired quality characteristics. The interaction effects among various parameters have also been presented. An increase of approximately 18% in MRR and a reduction of 26% and 11% in TWR and SR, respectively, were observed, during the machining through CEDM in contrast to EDM. The confirmatory experiments suggested that experimental values were in permissible agreement with the predicted values for all the performance measures. Finally, the comparison of the CEDM with that of EDM process, in the light of SEM graphs, has been presented.     

Modeling and Optimization of Machining Nimonic C-263 Superalloy using Multicut Strategy in WEDM

In recent years, wire-electrical discharge machining (WEDM) has gained popularity in the industry due to its capability to generate complicated shapes in exotic materials, irrespective of their hardness. Conventional machining of Nimonic C-263 superalloy is an extremely difficult and costly process due to its high hardness and tool wear rate. The present research work investigates the influence of the WEDM process parameters on different performance measures during machining of Nimonic C-263 superalloy. A mathematical model for all four important performance measures, namely, cutting rate, surface roughness, spark gap, and wire wear ratio, was developed and the responses were used for studying the interrelationship between performance measures and process parameters. The optimal settings of operating conditions were predicted using desirability function. The effectiveness of multicut strategy was also investigated in the article.     

Parametric Evaluation on Near-Dry Electric Discharge Machining

Near-dry electric discharge machining (EDM) is an eco-friendly process. It does not produce toxic fumes and consequent health hazards. The near-dry EDM generally utilizes a mixture of two phase (liquid and air) dielectric for machining. This investigation reports the influence of four processing parameters, viz. current, flushing pressure, duty factor, and lift on three responses. The responses measured were material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR). The work material chosen was high speed steel (HSS). Mathematical models have been proposed herein for evaluation of the effect of processing parameters in near-dry EDM. These models were developed using response surface methodology (RSM). The experimental results reveal that the process parameters taken into consideration were significant for MRR. The TWR was negligible in near-dry EDM. This process gives a finer surface finish with thinner recast layer even at higher discharge energies as compared to conventional EDM.     

Optimizing machining parameters of wire-EDM process to cut Al7075/SiCp composites using an integrated statistical approach

Metal matrix composites (MMCs) as advanced materials, while producing the components with high dimensional accuracy and intricate shapes, are more complex and cost effective for machining than conventional alloys. It is due to the presence of discontinuously distributed hard ceramic with the MMCs and involvement of a large number of machining control variables. However, determination of optimal machining conditions helps the process engineer to make the process efficient and effective. In the present investigation a novel hybrid multi-response optimization approach is proposed to derive the economic machining conditions for MMCs. This hybrid approach integrates the concepts of grey relational analysis (GRA), principal component analysis (PCA) and Taguchi method (TM) to derive the optimal machining conditions. The machining experiments are planned to machine Al7075/SiCp MMCs using wire-electrical discharge machining (WEDM) process. SiC particulate size and its weight percentage are explicitly considered here as the process variables along with the WEDM input variables. The derived optimal process responses are confirmed by the experimental validation tests and the results showed satisfactory. The practical possibility of the derived optimal machining conditions is also analyzed and presented using scanning electron microscope examinations. According to the growing industrial need of making high performance, low cost components, this investigation provide a simple and sequential approach to enhance the WEDM performance while machining MMCs.     

Effect of tool rotation in near-dry EDM process on machining characteristics of HSS

Rotary tool near-dry electrical discharge machining (RT-ND-EDM) is a process variant of EDM, which utilizes two phase dielectric medium instead of a conventional liquid or gaseous dielectric medium. The present work, RT-ND-EDM was investigated while machining of high speed steel (AISI M2 grade) using glycerin-air dielectric medium. The effect of various input process parameters was investigated on material removal rate (MRR), surface roughness (SR), and hole overcut (HOC). The input parameters considered were tool rotation speed, current, pulse on time, liquid flow rate, and gas pressure. Experiments were designed and conducted using response surface methodology. Regression models were also developed. The results revealed that the tool rotation speed has a significant effect on MRR, SR, and HOC. FE-SEM micrographs showed that the machined surfaces obtained by RT-ND-EDM have relatively lower micro-cracks, debris accumulation and craters. Also, deep through holes were successfully drilled in 24 mm plate using RT-ND-EDM process.     

Constrained multi-objective optimization of EDM process parameters using kriging model and particle swarm algorithm

This paper investigates the highly nonlinear relationship between process parameters and machining responses, including material removal rate (MRR), surface roughness (SR), and electrode wear rate (EWR) of electric discharge machining (EDM) using Kriging model. Subsequently, an emerging multi-objective optimization algorithm called particle swarm is used to determine the best machining conditions that not only maximize the machining speed but also minimize the EWR with a constraint of the SR. The experiment was carried out with P20 steel on a CNC EDM machine using copper electrode. The research result shows that the MRR increases sharply when increasing the discharge current just like other researches pointed out. However, the relationship between EWR and current is complicated. EWR appears the minimum value when the current is around 30?A. The speed of change of MRR per unit of EWR is the highest when the SR is around 14.5?µm. The combination of Kriging regression model and particle swarm optimization is considered as an intelligent process modeling and optimization of EDM machining. The proper selection of process parameters helps the EDM operator to reduce the machining time and cost.     

Mathematical modeling and analysis of WEDM machining parameters of nickel-based super alloy using response surface methodology

Inconel 625 is one of the most versatile nickel-based super alloy used in the aerospace, automobile, chemical processing, oil refining, marine, waste treatment, pulp and paper, and power industries. Wire electrical discharge machining (WEDM) is the process considered in the present text for machining of Inconel 625 as it can provide an effective solution for machining ultra-hard, high-strength and temperature-resistant materials and alloys, overcoming the constraints of the conventional processes. The present work is mainly focused on the analysis and optimization of the WEDM process parameters of Inconel 625. The four machining parameters, that is, pulse on time, pulse off time, spark gap voltage and wire feed have been varied to investigate their effects on three output responses, such as cutting speed, gap current, and surface roughness. Response surface methodology was used to develop the experimental models. The parametric analysis-based results revealed that pulse on time and pulse off time were significant, spark gap voltage is the least significant, and wire feed as a single factor is insignificant. Multi-objective optimization technique was employed using desirability approach to obtain the optimal parameters setting. Furthermore, surface topography in terms of machining parameters revealed that pulse on time and pulse off time significantly deteriorate the surface of the machined samples, which produce the deeper, wider overlapping craters and globules of debris.     

Performance evaluation of Al2O3 nano powder mixed dielectric for electric discharge machining of Inconel 825

Electrical discharge machining (EDM) process is popular for machining conductive and difficult-to-cut materials, but low material removal rate (MRR) and poor surface quality are major limitations of the process. These limitations can be overcome by adding the suitable powder in the dielectric. The powder particles influence electric field intensity during the EDM process which in turn improve its performance. The size (micro to nano) and properties of the mixed powder also influence the machining efficiency. In this regard, the objective of the present work is to study the performance of EDM process for machining Inconel 825 alloy by mixing Al₂O₃ nanopowder in deionized water. The experimental investigation revealed that maximum MRR of 47?mg/min and minimum SR of 1.487?µm, which are 44 and 51% higher in comparison to conventional EDM process, respectively, can be achieved by setting optimal combinations of process parameters. To analyze these observed process behavior, pulse-train data of the spark gap were acquired. The discharge waveform identifies the less arcing phenomenon in the modified EDM process compared to conventional EDM. Further, surface-topography of the machined surface was critically examined by capturing field emission scanning electron microscopy and atomic force microscopy images.     

WEDM of layered composite: analyzing material removal and cut quality issues

The use of cladded bimaterial composites has grown in the recent past as they offer a combination of properties at low cost. But the heterogeneity which is the inherent attribute of these composites makes it challenging to accurately cut via conventional means. Therefore, thermal cutting is commonly employed for their cutting which not only produce poor cut quality and deeper heat affected zones but also demand subsequent finishing operations. Wire electric discharge cutting (WEDM) is a proficient alternate but low material removal (MRR) and widen kerf slot (KW) due to sideways sparking limit its application. Moreover, both layers of material have different thermoelectric properties and are subjected to simultaneous cutting by a single moving wire electrode which lead to produce different spark strength against both layers. In this regard, the present study aims to investigate the cutting potential of WEDM for cladded bimaterial with a prior focus on both the aforesaid issues, i.e. MRR and KW. Considering the thermoelectric nature of the WEDM, workpiece-related parameters like orientation of work surface and layer thickness of each layer are taken as control variables in addition to the WEDM process parameters. Experimental results are thoroughly analyzed using statistical and SEM analysis.     

Experimental investigations into the performance of EDM using argon gas-assisted perforated electrodes

In the present work, a parametric study of EDM process using Argon-Gas-Assisted EDM (AGAEDM) with rotary tool during machining of high chromium high carbon diesteel has been performed. The pulse on time, tool rotation, discharge current, duty cycle, and gas pressure were selected as process factors. The effects of process factors were investigated on responses viz. surface roughness (SR), material removal rate (MRR), and electrode wear ratio (EWR). A comparison between solid tool, air-assisted tool, and argon-assisted tool has also been presented. It was found that EWR and SR were less during AGAEDM process as compared to rotary EDM(REDM) with solid tool and air-assisted EDM (AAEDM) with rotary tool under same process parameters. However, MRR was found to be higher in AAEDM process. The regression analysis and analysis of variance have been done to develop and find the adequacy of the developed models of MRR, EWR, and SR. It was observed that surface integrity of workpiece machined by AGAEDM was better than workpiece machined by AAEDM and conventional REDM process.     

Insights into process innovation through ultrasonically agitated concentric flow dielectric streams for dry wire electric discharge machining

Application of gaseous dielectric in place of liquid dielectric for wire electric discharge machining (WEDM), popularly known as dry wire electric discharge machining (DWEDM), offers technological solutions to some environmental and metallurgical issues pertaining to process. However, conventional side jet stream of dielectric in dry WEDM renders ineffective debris removal from sparking gap to cause unwanted arcing. Moreover, side thrust on the wire surface tends to induce wire vibrations and results into uneven geometrical profiles. To harness full potential of DWEDM technology, it is imperative to improve cutting characteristics of process by minimizing the adverse impacts of side jet stream of dielectric. In this research work, the authors have conceptualized and demonstrated the idea of using concentric flow pattern of gaseous dielectric as a novel technological solution to limitations of DWEDM process by introducing ultrasonic-agitated concentric dry wire electric discharge machining (UCDWEDM). Experiments have been performed on Ti–6Al–4V material. Ultrasonically agitated pressurized air streams were supplied through indigenously developed concentric and side flow nozzles mounted on experimental set up. The experimental results showed that concentric flow mode of dielectric supply has outperformed the conventional side flow mode with 42% higher CV, 22% lower SR, and 8% lesser KW. Process mechanism of UCDWEDM is based on high velocity of air in concentric flow and ultrasonic-agitation in spark gap and suggested that UCDWEDM has potential to replace conventional dielectric supply system in DWEDM.     

Modeling of cutting speed (CS) for HSLA steel in wire electrical discharge machining (WEDM) using moly wire

The high capital costs of wire electrical discharge machining (WEDM) equipment necessitate optimal utilization of the WEDM process and equipment. Cutting speed (CS) is a key performance measure to achieve this objective. However, process parameters of WEDM greatly hamper CS and hence productivity and machining efficiency. It is therefore essential to pick the right combination of parameters to attain better CSs. In this paper, five process parameters which include pulse on-time, pulse off-time, pulse frequency, power, and wire speed were used to develop an empirical relationship between process parameters and CS. A regression model based on experimental data was developed and validated through confirmation tests. Experiments have been conducted on high-strength low-alloy steel using molybdenum wire. Analysis of variance was applied to segregate significant process parameters and it was revealed that pulse off-time, power, and pulse frequency were the major parameters affecting CS. Contour plots have been established to select the best process parameters in addition to the developed model. Stability of moly wire was also explored using scanning electron microscope and energy dispersive spectroscopy analysis. Results showed that moly wire retains its original surface quality and dimensions which contributes to dimensional accuracy of parts.