Electro-discharge Machining Research Articles

MULTI-OBJECTIVE OPTIMIZATION OF EDM PROCESS PARAMETERS USING RSM-BASED GRA AND TOPSIS METHOD FOR GRADE 6 TITANIUM ALLOY

In this study, an attempt has been taken to find out the appropriate optimal parameter setting that will provide the best quality product depending on experimental data during Electro Discharge Machining (EDM) of Titanium grade 6 alloy with the help of brass electrode and to compare the optimized results achieved from two optimization techniques. For this study, Face Centered Central Composite Design- (FCCCD) based Response Surface Methodology (RSM) coupled with Technique for order of preference by similarity to ideal solution (TOPSIS) and Grey Relational Analysis (GRA) has been applied to optimize the process parameters i.e. gap voltage ([Formula: see text], peak current ([Formula: see text], pulse on time ([Formula: see text], and duty cycle ([Formula: see text]). Radial overcut (ROC), surface roughness ([Formula: see text], material removal rate (MRR) and tool wear rate (TWR) are selected as output performance characteristics. To find out the significant process parameters, Analysis of variance (ANOVA) test has been performed at 95% confidence level. For validation of the study, confirmation experiments have been performed at optimal parameters setting which show the enhancement of Relative Closeness Coefficient ([Formula: see text] up to 0.144082 using TOPSIS and Grey Relational Grade (GRG) up to 0.198014 using GRA, respectively.

Experimental investigation of Electro discharge machining process by AHP-MOORA technique

In the current study, Analytic Hierarchy Process (AHP) combined with Multi-objective optimization by ratio analysis (MOORA) was adopted to find the efficiency of optimizing multiple performance characteristics for EDM of Al-4.5%Cu- SiC composite using a cylindrical copper electrode. The influence of three machine process parameter pulse on (TON), peak current, duty cycle, and one material variable weight fraction on the response variables material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR) have been investigated using multi-attribute decision- making model. The response surface methodology (RSM) central composite designs (CCD) have been used as the experiment's design. The weight factors for the output responses assigned by the AHP method and the most desirable significant factor levels determined by the MOORA method. The method implemented in this paper is advantageous in various real-life decision-making problems in the manufacturing environment.

APPLICATION POTENTIAL OF RESPONSE SURFACE METHOD ON ELECTRO DISCHARGE MACHINING OF AA6061–CENOSPHERE AMCs PREPARED BY COMPOCASTING METHOD

Cenosphere fly ash particles are incorporated into AA6061 alloys with different concentrations ranging from 0[Formula: see text]wt.% to 10[Formula: see text]wt.% using a modified semi-solid metal processing technique. X-ray diffraction patterns were recorded to analyze the morphology of the aluminum-based metal matrix composites (AMCs). The major diffraction peaks of Al, SiO2, Al2O3 and Fe2O3 are distinctly identified which revealed the presence of cenosphere particles and their integrity within the matrix is preserved. The high-resolution optical micrograph identifies the homogeneous distribution and uniform dispersion of the particles. Machinability of the prepared AMCs was investigated by electro discharge machining (EDM) using response surface methodology (RSM). Face-centered CCD of RSM was considered to design the number of experimental runs required. ANOVA was used to explore the influence of selected process parameters and their interactions on the performance characteristics of the systems by developing a second-order quadratic mathematical model for all the responses. Pulse on-time and pulse current were observed to be the most influencing independent variables of EDM system that affect the selected performance measures during spark erosion process. Finally, desirability function approach was employed to optimize the parameters. The optimal processing condition was identified as follows: pulse current: 6 A, pulse on-time: 1010[Formula: see text][Formula: see text]s, percentage of reinforcement: 2% and flushing pressure: 0.2 MPa. Very small percentages of deviation have been observed while comparing with the experimental results obtained for MRR (8.6%), TWR (10.3%) and SR (2.18%).

Surface Integrity Enhancement of Incoloy 825 During Electric Discharge Machining

The aim of the current research work is to enhance the surface integrity of EDMed (electro-discharge machined) Incoloy 825 by suspending graphite powder particles in dielectric during electro-discharge machining (EDM). For this purpose, a specially designed and fabricated re-circulation dielectric tank was integrated with the existing EDM setup. The effect of three process variables, i.e., peak current, pulse-on time, and duty cycle was studied on EDM characteristics such as material removal rate, surface roughness (Ra), radial overcut, surface microhardness, microhardness in sub-surface regions, recast layer, phase changes and residual stress. Results showed that the machining rate increased up to 23% using powder-mixed EDM compared to conventional EDM. Significant reduction in surface roughness, white layer thickness, surface cracks and residual stress was observed while machining with graphite mixed dielectric. The addition of powder resulted in the formation of carbides and other alloy compounds on the machined surface which enhances the microhardness of surface and subsurface region.

Effect of a Rapid Tooling Technique in a 3D Printed Part for Developing an EDM Electrode

The role of rapid tooling (RT) in additive manufacturing (AM) seems essential in improving and spreading out the vista of manufacturing proficiency. In this article, attempts were made to discover the feasibility and the accomplishments of the RT electrode in the field of electro-discharge machining (EDM). Fused deposition modeling (FDM) is one of the AM processes adopted to fabricate the EDM electrode prototype by coating with copper. The copper is deposited on FDM-built ABS plastic component for about 1 mm through thick electroplating. The copper-coated FDM (CCF) and solid copper (SC) electrodes are used to conduct experiments on a die-sinking EDM machine using tool alloy steel as a workpiece. The CCF polymer electrode can be efficiently used in EDM operations as the build time of any complex shape was substantially reduced. However, the material removal rate (MRR) is far less than that of the SC electrode. It is recommended that the CCF electrode is used for semifinishing and finishing operations in which MRR happens to be less. However, CCF can get spoiled as high temperatures are generated on the machining tool, and the plastic core hardly sustains such high temperatures.

Effect of laser parameters on sequential laser beam micromachining and micro electro-discharge machining

Laser beam micromachining (LBMM) and micro electro-discharge machining (μEDM) based sequential micromachining technique, LBMM-μEDM, has drawn significant research attention to utilize the advantages of both methods, i.e., LBMM and μEDM. In this process, a pilot hole is machined by the LBMM, and subsequently finishing operation of the hole is carried out by the μEDM. This paper presents an experimental investigation on the stainless steel (type SS304) to observe the effects of laser input parameters (namely, laser power, scanning speed, and pulse frequency) on the performance of the finishing technique, that is, the μEDM in this case. The scope of the work is limited to 1-D machining, i.e., drilling microholes. It was found that laser input parameters mainly scanning speed and power influenced the output performance of μEDM significantly. Our study suggests that if an increased scanning speed at a lower laser power is used for the pilot hole drilling by the LBMM process, it could result in significantly slower μEDM machining time. On the contrary, if the higher laser power is used with even the highest scanning speed for the pilot hole drilling, then μEDM processing time was faster than the previous case. Similarly, μEDM time was also quicker for LBMMed pilot holes machined at low laser power and slow scanning speed. Our study confirms that LBMM-μEDM-based sequential machining technique reduces the machining time, tool wear, and instability (in terms of short circuit count) by a margin of 2.5 x, 9 x, and 40 x, respectively, in contrast to the pure μEDM process without compromising the quality of the holes.

Fabrication Methods for Microfluidic Devices: An Overview.

Microfluidic devices offer the potential to automate a wide variety of chemical and biological operations that are applicable for diagnostic and therapeutic operations with higher efficiency as well as higher repeatability and reproducibility. Polymer based microfluidic devices offer particular advantages including those of cost and biocompatibility. Here, we describe direct and replication approaches for manufacturing of polymer microfluidic devices. Replications approaches require fabrication of mould or master and we describe different methods of mould manufacture, including mechanical (micro-cutting; ultrasonic machining), energy-assisted methods (electrodischarge machining, micro-electrochemical machining, laser ablation, electron beam machining, focused ion beam (FIB) machining), traditional micro-electromechanical systems (MEMS) processes, as well as mould fabrication approaches for curved surfaces. The approaches for microfluidic device fabrications are described in terms of low volume production (casting, lamination, laser ablation, 3D printing) and high-volume production (hot embossing, injection moulding, and film or sheet operations).

Preface

Thanks for your supports to 2021 6th International Conference on Green Materials and Environmental Engineering (GMEE2021) and excellent paper submissions. GMEE2021 aims to conduct discussion in depth around Green Materials (including but not limited in Nanomaterials and Nanotechnology, Energy and Harvesting Materials, Structure of materials characterization and testing, Energy technology, Renewable energy economics, etc.) and Environmental Engineering (containing Advanced Oxidation Processes, Clean Energy and Sustainability, Environmental evaluation of renewable energies, Integrated ecosystems management, Power & Energy Engineering. etc.).Due to the severe impact of Covid-19 and the travel restrictions, GMEE2021 was held via Tencent Online Meeting on February 3, 2021, which ensures the safety of all participants, and has been well understood and strongly supported by the authors. In this virtual meeting including Keynote Speech, Oral presentations, Poster presentations, Q & A section, 30 participants from China, South Korea, Russia and 2 keynote speakers from Taiwan and India made wonderful presentations. Each oral presentation within 10 minutes and keynote speech within 45 minutes greatly stimulate others passion. And after each presentation, here was 5mins Q & A section, in which all participant can obtain fresh ideas in discussion and brain storming.Especially thanks their wonderful keynote speeches and active participations of Prof. Hui-Ming Wee from Chung Yuan Christian University, Taiwan and Prof. K. M. Pandey from National Institute of Technology Silchar, India. Prof. Hui-Ming Wee made his keynote speech entitled Sustainable Supply Chains under Carbon Cap Scheme and elaborated on his latest academic research. Prof. K. M. Pandey made his brilliant and remarkable speech around Investigation on the Wire Electro Discharge Machining Behavior of Alimino Silicate Partieles Reinforced AA6061 Alloy Prepared by Compocasting Process.With professional assistances and guidance from Technical Program Committee on paper reviewing and checking, GMEE2021 finally selected 44 papers among 150 submissions covering Green Materials and Environmental Engineering. All these accepted papers have been reviewed by 2-3 reviewers and editors majoring in relevant research areas and be detected instances of overlapping and similar text in submitted manuscripts via iThenticate software before submitting for publication in IOP Conference Series: Earth and Environmental Science.Much appreciation to the sponsor of Advanced Science and Industry Research Center, Hong Kong, IOP Publishing with effective publication for excellent paper submissions, all the outstanding authors with innovative research findings, all the members and reviewers in GMEE2021 Technical Program Committee with careful reviewing and overwhelming response. We sincerely hope you can enjoy the conference and learn more from this academic sharing and exchanging. Looking forward for the future cooperation with you.List of Committees are available in this pdf.

Prediction of white layer formation in μ-WEDM process of NiTi shape memory superalloy: FEM with experimental verification

Microscopic changes in the surface of nickel-titanium (nitinol) shape memory alloys (SMAs) in micro-wire electro-discharge machining (μ-WEDM) due to the formation of a resolidified layer on the machined surface, called white layer, are one of the main drawbacks in the processing of such alloys. Since these changes significantly affect the shape memory and elastic recovery characteristics of these alloys, reduction of the white layer thickness (WLT) based on the selection of optimum process parameters is essential to raise the quality of the machined parts. In this regard, a finite element model (FEM) has been developed to simulate the effects of μ-WEDM process parameters, including discharge current, pulse on-time, pulse off-time, and servo voltage, on the heat distributing in Ni55.8Ti SMA to predict the WLT. The flushing efficiency of electric discharges and the effect of flow regime of the dielectric fluid on the heat distribution in the workpiece and the formation of the WLT are analyzed. Experimental data are used to verify the accuracy of the FEM. The results show that the developed model can predict the WLT in μ-WEDM process of Ni55.8Ti SMA with an average error of 14%. The effects of discharge parameters on the formation of the WLT are discussed in details based on the results of the FEM.

Novel approach in experimental and statistical investigations on titanium matrix composite

Titanium matrix composite (TMC) is comprehensively used in aerospace, turbo-machinery, automobiles and bio-medical industries for its improved strength properties and wear, corrosion and fatigue resistance. The major aim of this paper is to focus on the development of the current state-of-art of improving the tribo-mechanical properties by developing the TMC through laser engineering net shaping (LENS) process. A novel approach has been proposed in the multi-objective optimization (MOO) technique by combining grey relational analysis with desirability, named as desirable grey relational analysis (DGRA). The main advantage of incorporating such, is to include the predicted responses obtained by response surface methodology (RSM) with the actual experimental performances. Advanced non-traditional machining like wire electro-discharge machining (WEDM) has been used for the experimental runs on the developed TMC by varying power (P), time off (Toff) and peak current (IP) as chief input process parameters. Box–Behnken design (BBD) model has been projected to obtain MOO on key performance measures, like material removal rate (MRR), surface roughness (SR), kerf width (KW) and over cut (OC). The optimized solution is improved by 1.022% when compared with desirability approach to novel DGRA technique. MRR is enhanced by 1.463%, SR by 13.221%, KW by 1.594% and OC by 6.025% when compared with DGRA method.

Multiple-objective optimization of hydroxyapatite-added EDM technique for processing of 316L-steel

ABSTRACT Fabrication of the 316 L steel with moderate surface roughness (SR) and thin recast layer (RLT) is very difficult using both the conventional and non-traditional machining processes. Due to the stochastic behavior of electro-discharge machining (EDM) process, the machining performances significantly rely on the system variables. This research work aims to investigate the influences of EDM method variables on the machining performances during the machining of 316 L steel. Another goal is to minimize the performances by applying nano-hydroxyapatite (HA) particles in the EDM-Oil. Moreover, the optimal solutions for processing of 316 L through the NSGA-II method are proposed in this research. Followed by the pulse-on time and HA amount, ANOVA study reports peak current being the most important parameter for the responses such RLT and SR. The augment of peak current, HA amount, and pulse-on time result comparatively lower RLT and SR than the previous studies. The best 7 solutions selected from the predicted 120 solutions following the objectives are proposed generating the Pareto frontiers. Less than 10% of the validation tests errors confirm the high accuracy of the predicted solutions. The present research proposed a potential and cost-effective method for processing of 316 L steel.

Experimental investigation on WEDM performance analysis using grey-fuzzy integrated with TLBO algorithm for Inconel 625: comparison with GA and SA

Purpose In the present study, wire electro-discharge machining (WEDM) of Inconel 625 (In-625) is performed with the machining parameter such as spark-on time, spark-off time, wire-speed, wire tension and servo voltage. The purpose of this study is to find the most favorable machining parameter setting with respect to WEDM performance such as material removal rate (MRR) and surface roughness (RA). Design/methodology/approach Taguchi’s L27 orthogonal array has been used to design the experiments with varying machining parameters into three-level four factors. A hybrid multi-optimization technique has been purposed with grey relation analysis and fuzzy inference system integrated with teaching learning-based optimization to achieve optimum machinability (MRR and RA in present case). The obtained result has been compared with two evolutionary optimization tools via a genetic algorithm and simulated annealing. Findings It has been found that proposed hybrid technique taking minimum computational time, provide better solution and avoid priority weightage calculation by decision-makers. A confirmation test has been performed at single and multi-optimal parameter settings. The decision-makers have been chosen to select any single or multi-parameter setting as per the industry’s demand. Originality/value The proposed optimization technique provides better machinability of In-625 using zinc-coated brass wire electrode during WEDM operation.

Surface characterization of the seating platform of titanium implant processed with different textures

Manufacturing processes imply different ranges of surface roughness, such as found in dental components. These surfaces have vital roles from a clinical perspective, including essential biocompatibility, bacterial adhesion, and prosthetic retention. However, the relationship between the surface topography and these characteristics can be more detailed, especially in texture analysis. For this purpose, three specimens were studied: (i) Ti-6Al-4V alloy manufactured by wire electro-discharge machining (WEDM); (ii) Ti-6Al-4V alloy manufactured by WEDM followed by electropolishing (WEDM + EP); and (iii) a seating platform of dental implant CNC-machined, manufactured in Ti–CP. Surface topography was analyzed through optical interferometry, using the following parameters: Sq (root mean square), Sp (max peak height), Sv (max valley depth), Ssk (skewness), Sku (kurtosis), and Str (texture aspect ratio). The application of the electropolishing process was sufficient to remove all irregularities left by WEDM, rounding the peaks and valleys, meaning a reduction of 69% in Sq value. On the other hand, the deviations in the seating platform’s height distribution can be considered critical for generating a misfit between the implant–abutment pair. In this case, electrochemical machining is recommended for this surface, instead of grinding processes.

Effect of Cu and Ti electrodes on surface and electrochemical properties of Electro Discharge Machined (EDMed) structures made of Co-Cr and Ti dental alloys

ObjectivesPrevious studies have shown that the use of Cu electrodes compromises the electrochemical properties of Co-Cr and Ti alloys used for the fabrication of implant retained superstructures by Electro Discharge Machining (EDM). A possible solution is the use of Ti instead of Cu electrodes and thus the aim of this study was to evaluate the effect of Cu and Ti electrodes on surface and electrochemical properties of two types of dental alloys used for fabrication of implant retained superstructures after EDM. MethodsThree full arch frameworks were prepared from a Co–Cr and three from Ti6Al7Nb alloy. One framework from each alloy was used as control, one was subjected to EDM with Cu electrodes and the last one with Ti electrodes. Morphological and elemental characterization was studied by SEM/EDX. The electrochemical properties of the alloys were evaluated by Open Circuit Potential (OCP) and Linear Sweep Voltammetry (LSV) in Ringer’s solution. Electrochemical data were analyzed statistically by one way ANOVA and SNK multiple comparison tests at a = 0.05 ResultsAll groups demonstrate the typical surface after EDM treatment with almost circular valleys and an increase in C and O content compared to control groups. Both alloys demonstrated an uptake of C and Cu by Cu electrodes and C and Ti after treatment with Ti electrodes. The use of Cu electrodes had a detrimental effect on corrosion resistance of Ti alloy. SignificanceThe use of Ti electrodes mitigates the degradation of electrochemical properties compared to Cu electrodes and from this standpoint is safer for the EDM of implant retained superstructures made of Co-Cr and Ti alloys.

Electrically conductive and thermally stable SiC‐TiC containing nanocomposites via flash pyrolysis

AbstractFlash pyrolysis, which combines conventional pyrolysis with flash sintering, was first conducted to produce polymer derived SiC‐TiC nanocomposites. Pre‐pyrolysis at 800℃ allows the conversion from titanium isopropoxide (TTIP) modified polysiloxane to an amorphous SiTiOC ceramic. The subsequent application of an electric field gives rise to the formation of turbostratic carbon and creates Joule heating to obtain a sample internal temperature of ~1400℃. The precipitation of β‐SiC, TiC, as well as titanium oxides is realized upon carbothermal reduction of extensively phase separated SiO2 and TiO2 with carbon. Increasing TTIP content embodies the nanocomposites with prominent electrical percolation behaviors. The electrical transport of the synthesized ceramics follows an amorphous semiconductor mechanism. High thermal stability in air is guaranteed, thanks to the in‐situ formed TiC nanocrystals and preferentially reduced amorphous carbon. Flash pyrolyzed nanocomposite with a Ti:Si molar ratio of 0.20 exhibits the highest electrical conductivity (0.696 S/cm) and minimum mass change (~2%) at 1000℃, serving as a competitive candidate for electro‐discharge machining (EDM) applications or self‐standing conducting devices that must withstand high temperature conditions.

Micro-EDM-assisted machining micro-holes in printed circuit board

Printed circuit board (PCB) can provide assembly support and electrical connection for components in electronic systems. The machining of micro-holes in PCB is a necessary process and key step for its application in electronic components. Therefore, micro-holes are the key structures of PCB. At present, high-speed drilling based on micro-bit is the key supporting technology for machining PCB micro-holes. However, when the copper foil layer in PCB is machined by this technology, the micro-holes are prone to defects such as hole mouth burr and hole nail head, which could seriously affect the performance of PCB. Focusing on the above problems, this paper proposed to use micro electro-discharge machining (micro-EDM) for assisted machining of PCB micro-holes. With this method, the copper foil layer in PCB was machined by micro-EDM, so as to remove hole mouth burr and hole nail head. The paper detailedly studied the influence of micro-EDM voltage, pulse width and pulse interval on hole mouth burr and hole nail head. Finally, under the effects of 10,000 rpm rotational speed, 40 V voltage, 80 ns pulse width and 160 ns pulse interval, the micro-bit with diameter of 200 μm was used to carry out micro-EDM-assisted machining of the copper foil in PCB. From the machining results, it can be found that the hole mouth burr and the hole nail head were basically eliminated and PCB micro-holes with good quality were obtained by the proposed method.

Surface modification of tool steel by using EDM green powder metallurgy electrodes

Electro-discharge machining (EDM) is mostly used for machining difficult-to-cut materials which are difficult to machine by conventional machining processes. In recent years, EDM is also used for surface modification. This work aims to investigate the phenomenon of surface modification of tool steel Calmax (Uddeholm) by EDM process using Cu-ZrO2 powder metallurgy green compact electrode. Results show that the higher Material Transfer Rate of 46.5 mgr/min is achieved on the combination of Ip=9A and Ton=25 μs. The effect of peak current and pulse duration on the material transfer rate and surface roughness (Ra and Rz) was investigated. Machined surfaces were characterized by scanning electron microscopy (SEM).

Investigation of the Effect of Wire Electrical Discharge Machining on the Fracture Toughness of Aluminum-Boron Carbide Composite

Aluminum metal matrix composites reinforced by ceramic particles have a wide acceptance in engineering applications due to their mechanical and physical properties. One of the major challenges in machining these composites by the conventional machining operations is the presence of the abrasive particles, which affects the tool life and the required surface finish. Electro discharge machining process is widely used instead of conventional methods to overcome these challenges. Therefore, it is essential to study the influence of the electro-discharge machining on its fracture toughness, as it is the most important structural integrity indicator in the wide range applications of the studied composites. In this work, all samples were prepared by the stir casting method with using a squeezing pressure during the solidification. Samples were reinforced by (0, 2, 4, and 6wt %) of B4C particles with a size of 0.387μm. The fracture toughness studied were based on the stress intensity factor, determined experimentally by using compact tensile test and numerically using the finite element method. The fracture toughness improvement was recorded for the samples containing 4wt% of B4C.

WITHDRAWN: Investigations on hybrid multichannel electrode based EDM process constraints

Miniature Electro Discharge Machining (miniature EDM) is one of the most manageable cycles used to machine 3D highlights on metallic surfaces. It is viable technique for machining incredibly hard and hard to cut materials. Material is taken out from anode surface principally by heat produced due controlled starting. Size and state of terminals assume noteworthy function in the soundness of the miniature EDM measure by overseeing the garbage flushing out of between cathode holes. This examination tends with the impact of calculations on the presentation of the miniature EDM measure. Planned examinations have been directed utilizing strong bar, single channel and multichannel terminals. Material evacuation rate (MRR) and device wear rate (TWR) being the significant pointers of miniature EDM measure; impact of various cycle boundaries on MRR and TWR have been assessed for various arrangement of tests. From the examination, a strong cathode has discovered a superior presentation than the other two kind of anode. Most elevated MRR and least TWR is watched for the strong terminal.

Model Prediction and Experimental Study of Material Removal Rate in Micro ECDM Process on Borosilicate Glass

Miniaturization of products has become a major technological challenge in production industries. Material removal in microscopic and sub-microscopic level has become a demand for producing such products. Electro-Chemical Discharge Machining (ECDM) is one of the hybrid non-conventional machining processes to machine materials that are electrically conductive and non-conductive at a micro-level utilizing the principles of Electro Discharge Machining (EDM) and Electro-Chemical Machining (ECM). The most common nonconductive materials machined with this process are various types of glasses, ceramics, composites, etc. In the current paper, a Finite Element Model (FEM) of the ECDM process is carried out in the discharge regime (less than 300 μm) with pulsed DC in a 2D domain to characterize the Material Removal Rate (MRR) as a process output response in borosilcate glass machining. From the model and experiements the value of MRR is found to be 0.373 mg/ min and 0.414 mg/min. It can be considered that there is almost negligible difference in MRR between experimental and model values with 9.9% error variation. Hence the results are validated with experimentation, and there is a good agreement observed between the results.