Rotary Electrical Discharge Machining Research Articles

To examine the effect of input parameters of rotary EDM on surface roughness of cryogenically treated Monel 400

Rotary electric discharge machining (REDM) has an advantage over traditional EDM in that the tool speed can be varied to achieve better surface characteristics of machined components. Cryogenic treatment also improves the machining efficiency of non-traditional machining processes such as EDM. REDM is used in this study to establish a relationship between response parameters and control parameters while machining cryogenic treated alloy Monel-400 with a cryogenically treatedcopper electrode. The RSM approach was used to design experiments to investigate the effect of parameters such as tool speed, peak current, pulse on time, and duty cycle on surface roughness. An experimentally validated regression modal has been proposed. As per SEM examination, the typical surface produced for the setting of low pulse energy (at pulse on time:100 µs; Current:12 A; duty factor: 0.40; and tool rotation = 800 rpm) is found to be finer and showing shallow carters.

Die-sinking and rotary EDM surface and subsurface analysis of MoSi2-SiC ceramic composites

Rotating EDM and die sinking EDM were used to compare the machinability of MoSi2-SiC composites. Surface flaws such as micro cracks, un melted spherical particles, pores, a recast layer and craters following EDM can be attributed to the high hardness and poor toughness of the MoSi2-SiC. Die sinking EDM and rotary EDM, as shown by a comparison of recast layer thicknesses, produce the most uniformly thin white layers, at 92 and 30 µm respectively. The study found that the area fraction yield for porosity ranged from 8.18% to 12.922% when using rotary EDM, but only from 2.33% to 8.10% when using die-sinking EDM. According to the EDAX, the spongy exterior of a composite is the result of a lot of gas being produced. Although the rotational movement of the tool sweeps the resolidified particles away, Rotary EDM resulted in a thinner and less uniform recast layer while still producing good surfaces.

Si3N4-TiN rotary EDM optimization by Mo-Jaya algorithm with Pareto optimal solution, analysis of micro-structural and geometrical tolerances

Research into rotary electrical discharge machining on high temperature with biomedical application Si3N4-TiN ceramic composite is presented in this paper. Current (I), pulse on time (Ton), pulse off time (Toff), dielectric pressure (DP), speed and spark gap voltage (Sv) are some of the many performance characteristics. Among the factors taken into account is the material removal rate, surface roughness, electrode wear rate, cylindricity, perpendicularity, top radial overcut, bottom radial over cut and run out. Multiple parameter combinations were validated experimentally and the resulting reactions were examined. Mean effects analysis and regression analysis are used to investigate the impacts of individual parameters. To comprehend the instantaneous behavior of the replies, multi-objective Jaya optimization is utilized to optimize the responses simultaneously. The multi-objective problem's outcomes are shown in 3D charts, with each showing the Pareto optimal solution. From this real conclusion, the optimal combinations of answers are extracted and reported. The aggregate optimization result was also shown, which factored in all eight responses. MRR of 0.238 g/min was obtained which is a 10.6% improvement from the experimental values. Electrode wear of 0.0028 g/min was obtained showing a 6.6% reduction. Similarly reduction in values of Surface roughness, top radial overcut and bottom radial over cut, Circularity, Perpendicularity, run out was observed and the percentages are 3.4, 4.7, 4.5, 7.8, 10.0 and 10.53 respectively. Details on the structural and morphological examinations of the various surface abnormalities that occur during the process have been presented.

On the creation of structured abrasive tools via multiple-pass rotary wire EDM: A geometrical model

On the creation of structured abrasive tools via multiple-pass rotary wire EDM: A geometrical model

Multi-performance characteristics optimization in near-dry rotary EDM of AlSiC by weighted principal component analysis

In the current study, electrical discharge machining of particle reinforced aluminium matrix composite (AlSiC) using near-dry conditions is investigated. The investigation has been carried out by using de-ionized water as liquid phase and air as gaseous phase of a two-phase dielectric fluid. The gap between the work material and the tool is supplied with a little amount of de-ionized water droplets at a slow, steady pace using a minimum quantity lubrication (MQL) device. The process parameters included in the study are peak current, duty cycle, pulse-on time, tool rotation and air pressure. MRR (Material removal rate), TWR (Tool wear rate) and HT (Hole Taper) were selected as evaluation criteria. L27 (313) orthogonal array was used to conduct the experiments. The experimental results obtained were used in principal component analysis (PCA). The MPI (multi-response performance index), which combines these principal components and weighted principal component analysis (WPCA), is calculated as overall performance index. The approach is capable of forecasting optimal levels of machining factors. Significant factors and their contribution is determined by ANOVA performed for MPI. To validate the optimum parametric settings confirmatory experiment was conducted. Experimental results show that the responses in near dry rotary EDM process can be successfully improved using the suggested method.

A Comparison Between AH 26 and Sealapex for Post-Obturation Pain

Objective: To find out the post-obturation pain with Sealapex and AH26 Sealers on the first, third and seventh day.
 Study Design: Quasi-experimental study.
 Place and Duration of Study: Armed Forces Institute of Dentistry, Rawalpindi Pakistan, from May to Nov 2019.
 Methodology: Three hundred eighty-eight patients of either gender, ranging from age 20 to 45, presenting in the OPD for root canal treatment were selected. Teeth were opened, cleaned and shaped properly with rotary HyFlex EDM files. Obturation was done with Sealapex sealer in half cases, and the rest were obturated using AH26. Post-operative pain was recorded with VAS scoring on the days 1,3 and 7.
 Results: Of 388 patients reporting, 131(67.5%) were males, and 63(32.5%) were females. Comparative pain recording on the days 1, 3 and 7 showed post-operative pain for the AH Sealer-Group as 80(58%), 64(72.3%), 22(84.3%) and Sealapex SealerGroup as 58(42%), 24(27.7%) and 4(15.7%) respectively. The difference between post-obturation pain of both groups on all days was statistically significant, with an increased pain in the AH 26 Sealer-Group. There was a statistically significant relation between post-operative pain with gender distribution. Younger patients reported more pain as compared to older subjects.
 Conclusion: The post-obturation pain for AH26 is more than Sealapex sealer which gradually decreases with each passing day.

Experimental investigation on surface morphology and recasting layer of Si3N4-TiN composites machined by die-sinking and rotary EDM

Si3N4-TiN composites have extensive manufacturing applications because of their first-rate mechanical and thermal properties. Conversely, they are very demanding on machines that use conventional practices because of their superior strength and hardness. Electrical discharge machining is a viable substitute for machining of Si3N4-TiN composites through electrical erosion. However, very few studies have been conducted on the machinability and surface characteristics of electrical-discharge-machined composites. This study focuses on the materials processing characteristics of a Si3N4-TiNcomposite using rotary EDM and die-sinking EDM performed with a Cu electrode. In addition, the surface and cross section of the subsurface of the composite were examined, along with energy dispersive X-ray analysis, to identify the elements present on the machined surface. It was found that the high level of hardness and low level of toughness of the Si3N4-TiN composite contributed to the presence of microcracks, globules, pores, recast layers, and craters on the EDMed surface. The recast layer thicknesses of the die-sinking EDM (optimum hole, 106 μm; best hole, 151 μm; worst hole, 166 μm) and rotary EDM (optimum hole, 53 μm; best hole, 55 μm; and worst hole, 58 μm) were examined. In addition, the presence of pores and ablation increased significantly during the rotary EDM process. Rotary EDM parameters capable of producing a minimum white layer thickness were also investigated. Finally, the porosity levels were estimated according to the number of pores using ImageJ software. For the die-sinking EDM, the estimated porosity values for the optimum, best, and worst holes were 14.989%, 19.525%, and 21.706% respectively and for the rotary EDM, these values were 24.873%, 33.04%, and 37.99% respectively.

Experimental investigation of machining of EN31 Steel in abrasive mixed rotary EDM with graphite and copper electrode

Experimental investigation of machining of EN31 Steel in abrasive mixed rotary EDM with graphite and copper electrode

Fabrication of Ultra-Fine and Ultra-Long Copper Tube Electrodes by Ultrasonic High-Frequency Percussion.

In this study, a new method of ultrasonic high-frequency percussion (UH-FP) is proposed. Ultra-fine and ultra-long copper tube electrodes cannot be fabricated by traditional processing methods, and the copper tube electrodes fabricated by UH-FP can be used in the process of rotary EDM for microfine holes. The UH-FP setup has been established based on an ultrasonic device, a workpiece chucking and rotation device, and a workpiece reciprocating motion device. In this work, by studying the principle of ultrasonic processing, the processing principle and mechanism of ultra-fine and ultra-long copper tube electrode preparation by ultrasonic high-frequency percussion is proposed. The effects of processing parameters (i.e., rotational speed, feed rate, working gap, percussion amplitude) on surface roughness are evaluated quantitatively. Experimental results show that the proposed method could complete the core leach of the core-containing copper tube electrodes after drawing, while improving surface quality. Some surface defects such as cracks, scratches and folds were completed removed, further improving the mechanical performance of processed parts. The surface roughness (Ra) of 0.091 μm was obtained from the initial 0.46 μm under the optimal processing parameters of 800 rpm tube rotational speed, 200 mm/min platform feed speed, 0.13 mm machining gap, 0.15 mm percussion amplitude, and 32 min machining time. The method shows potential for manufacturing copper tube electrodes for a wide range of industrial applications.

Compare of the Frequency of Instrument Fracture of Endodontic File Using Rotary Pro Tapers and HY Flex Series

Objective: To compare the frequency of instrument fracture of endodontic file using Rotary Pro Tapers and EDM Hy Flex series. Study Design & Setting: This experimental in vitro study was conducted at Institute of Dentistry Liaquat University of Medical and Health Sciences Jamshoro. Subjects and Methods: Data was prospectively collected from extracted human teeth. A total of 66 canals were included. Simple descriptive statistics were used to present demographic data, along with frequency and percentages to present qualitative variables. It was decided to perform a post-stratification chi square test taking a p-value of less than 0.05 as significant. Results: A total of 66 canals (33 each endodontic file using Rotary Pro Tapers and EDM Hy Flex series) were included. Mean endodontic file in group A and B was 1.28±0.14 mm and 0.58±0.08 mm. Comparison of instrument separation in endodontic file using Rotary Pro Tapers and Hy Flex series showed separation of 09 (27.3%) and 02 (6.1%) respectively. Conclusion: Based on the results of this study, Protaper files generated much more stress than EDM Hy Flex files, but comparisons of instrument separation between the two instruments showed that the latter performed better overall. Keywords: Root canal treatment, Endodontic file, Rotary Pro Tapers and Rotary EDM Hy Flex.

Influence of Rotary Assisted Electrical Discharge Machining of 17-4PH Stainless Steel Using Taguchi Technique

The current investigation has study the material removal rate, surface roughness and electrode wear rate in rotary toolassisted EDM of 17-4 PH stainless steel. 17-4 PH SS has widely used in aerospace, marine, nuclear, and chemicalprocessing due to their characteristic high strength to weight ratio and corrosion resistance properties. This paper primarilyfocuses on enhancing the flushing efficiency of dielectric fluid in the EDM process and to improve the machiningperformance characteristics. A custom designed rotating electrode attachment has fabricated and used to assist with theEDM process. The experiments are designed and planned using Taguchi L27 Orthogonal array technique.The experimentsare planned for four input factors and each parameter is varied at three levels. Current, pulse on time, pulse off time andElectrode Rotation Speed are input factors. ANOVA test is conducted to find out the significance of factors and theirpercentage contribution on the performance characteristics like Material Removal Rate, Surface Roughness and ElectrodeWear Rate. The resultsconcluded that Electrode Rotation Speed has more influence on Material Removal Rate and ElectrodeWear Rate. An individual percentage and interaction percentage of parameters from ANOVA confirm that their effectsare higher in Material Removal Rate (MRR) compared to Surface roughness (Ra) and Electrode Wear Rate (EWR). Finally,surface morphology studies revealed that significantly less cracks and voids had formed on the EDM’ed sample at optimumcondition.

Comparative study of rotary-EDM, gas assisted-EDM, and gas assisted powder mixed-EDM of the hybrid metal matrix composite

ABSTRACT Hybrid metal matrix composite is an integration of two or more reinforcements to produce better strength, stiffness, and high strength to weight ratio. However, low material removal and high electrode wear are some of the major obstacles in the EDM processing of hybrid metal matrix composites due to the fragile and non-conductive nature of the reinforcement ceramics. For this purpose, processes such as rotary electrical discharge machining (REDM), gas-assisted electrical discharge machining (GAEDM), and gas-assisted powder mixed electrical discharge machining (GAPMEDM) are compared on the basis of the material removal rate and the electrode wear rate. The metal removal rate obtained in the gas-assisted powder mixed electrical discharge machining process is up to 75% higher and the electrode wear rate is at least 25% lower than the REDM process. The metal removal rate acquired by the gas-assisted powder mixed electrical discharge machining process is at least 45% better and the electrode wear rate is at least 15% lower than the GAEDM process. Experimental findings show that MRR is better and EWR is lower in GAPMEDM compared to GAEDM and the conventional REDM process.

Modelling of Rotary EDM Process Parameters of Inconel 718 Using Artificial Neural Networks

Modelling is used for correlating the relationship between the input process parameters and the output responses during the machining process. To characterize real-world systems of considerable complexity, an Artificial Neural Network (ANN) model is regularly used to replace the mathematical approximation of the relationship. This paper explains the methodological procedure and the outcome of the ANN modeling process for Electrical Discharge Drilling of Inconel 718 superalloy and hollow tubular copper as tool electrode. The most important process parameters in this work are peak current, pulse on time and pulse off time with machining performances of material removal rate and surface roughness. The experiments were performed by L20 Orthogonal Array. In such conditions, an Artificial Neural Network model is developed using MATLAB programming on the Feed Forward Back Propagation technique was used to predict the responses. The experimental data were separated into three parts to train, test the network and validate the model. The developed model has been confirmed experimentally for training and testing in considering the number of iterations and mean square error convergence criteria. The developed model results are to approximate the responses fairly exactly. The model has the mean correlation coefficient of 0.96558. Results revealed that the proposed model can be used for the prediction of the complex EDM drilling process.

Machining performance enhancement of powder mixed electric discharge machining using Green dielectric fluid

Towards the requirement of sustainable development, manufacturing industries are required to follow ISO-14000 standards. Therefore, it is necessary to follow sustainability criteria for manufacturing processes. Vegetable oil-based fluids have proven their potential towards the various industrial applications and establish themselves as a sustainable fluids as compared to hydrocarbon and synthetic-based fluids. In the present study, the authors have evaluated the practical acceptability of newly proposed Schleichera oleosa (Kusum oil) as an alternative of hydrocarbon-based EDM oil. The improvement in machining performance of MWCNT mixed rotary EDMing of EN-31 die steel using Kusum oil as a dielectric is evaluated in terms of MRR and SR. Response surface methodology along with genetic algorithm is used for the mathematical modelling and optimization of MRR and SR both. The optimization result shows that MWCNT mixed rotary EDM using Kusum oil as a dielectric shows approximately 57.14% higher MRR and 54.57% lower SR, respectively, as compared to conventional EDM using EDM oil as a dielectric. Finally, the surface topography images obtained from FESEM analysis also confirm the superiority of Kusum oil over EDM oil.

Experimental investigation of flushing approaches on EDM machinability during machining of titanium alloy

The titanium alloy is extensively included in a number of industries. In addition, good machining of titanium alloy is incredibly difficult because of its high strength and rigidity. One of the key problems faced during EDM activity is the flushing out debris from the inter-electrode gap. Arcing and short circuit takes place when spark eroded matter collects in the discharge gap that lowers the performance of the EDM. The current research work is an attempt to explorer the effective flushing technique which can enhance the flushing action during the EDM operation. Comparative study of EDM with gas-assisted multi-hole rotary tool, EDM with rotary tool and EDM with traditional stationary tool with reference to process output such as tool wear ratio (TWR) and material removal rate (MRR) has been carried out in the proposed work. The experiments were performed with process variables such as discharge current, pulse on time, duty cycle, electrode speed, and gas pressure to their influence on MRR and TWR. In addition, it was observed from a comprehensive study that high MRR and low TWR are achieved in EDM with multi-hole rotary tool with gas assistance compared to EDM with rotary tool and EDM with traditional stationary tool. The findings suggest that using compressed argon gas in EDM with gas-assisted multi-hole rotary tool has a favorable impact on the overall of the machining process.

Optimization of Rotary Electrode EDM Process Parameters During Machining of Ti-6al-4v Alloy

Optimization of Rotary Electrode EDM Process Parameters During Machining of Ti-6al-4v Alloy

Machining performance enhancement of EN-31 diesteel using MWCNT mixed rotary EDM

The present study investigates the influence of adding multi-wall carbon nanotube (MWCNT) into the dielectric fluid of electric discharge machining (EDM) in terms of material removal rate (MRR), surface roughness (SR) and surface topology of EN-31 die steel using Cu electrode. A customized rotary electrode set-up has been developed to compare the performance improvement of powder mixed rotary electrical discharge machining (PMREDM) as compared to powder mixed electrical discharge machining (PMEDM) and conventional EDM. The present study attempts to investigate the optimization of process parameters of MWCNT mixed rotary EDM of EN-31 die steel using response surface methodology (RSM) and genetic algorithm (GA) in terms of MRR and SR. The optimization results show that MWCNT mixed rotary EDM shows highest value of MRR (9.72 mm3/min) and lowest value of SR (Ra = 2.03 μm), which are approximately 46.17% higher and 45.43% lower than conventional EDM values respectively. Further, various combinations of optimal values of MRR and SR and their corresponding input parameters setting have been shown in pareto table created by multi-objective optimization GA technique available in MATLAB. Finally, field emission scanning electron microscope (FESEM) analysis of MWCNT mixed rotary EDM and EDM surfaces is carried out which revealsthat MWCNT mixed rotary EDM shows better surface topography as compared to EDM process.

Experimental investigation and effects of process parameters on EDM of Al7075/SiC composite reinforced with magnesium particles

Abstract The recent paper presents the experimental investigation on material removal rate (MRR) and electrode wear ratio (EWR) of hybrid metal matrix composite of Aluminium 7075 reinforced with 10% by wt. Silicon carbide particles and nanoparticles of magnesium (Al 7075/10%SiC/Mg). Magnesium metal matrix composites are of significant importance nowadays because of the increasing demand of light weight structural material in aerospace and automotive applications. Stir casting process has been used for fabrication of hybrid metal matrix composite. The effect of process parameters on responses such as MRR and EWR are evaluated during conventional EDM and rotary EDM. The pulse duration, peak current, duty cycle, and tool speed are selected as machining parameters. A comparative analysis of conventional EDM and rotary EDM of hybrid composite has been done. Experimental results indicated that the rotation of the tool enhances the flow of dielectric and effective evacuation of the debris from the gap between the workpiece and tool. The result shows increased MRR and reduced EWR with rotary EDM as compared to conventional EDM. This work seems to be of novelty and the findings can be useful for aerospace and automotive industry.

An hybrid approach for multi-response optimization of rotary electrical discharge machining of nickel super alloy

Abstract RENE80 nickel super alloy is widely used in aerospace industry and difficult to machine due to its high hardness, high temperature strength and low thermal conductivity and high reactivity with the tools during machining. Hence it can be machined by non-traditional processes like EDM or its variants. In this paper, multi-response optimization of rotary EDM of RENE80 is carried out with copper electrode. ANOVA results indicate that peak current and rotational speed of electrode are significant contributors to various responses. Confirmation experiments showed significant improvements in radial overcut, surface roughness and metal removal rate as 8.73%, 20.82% and 17.93% respectively.

Cyclic fatigue resistance of three rotary file systems in a dynamic model after immersion in sodium hypochlorite.

To evaluate the effect of immersion in 3% sodium hypochlorite solution in the resistance to cyclic fatigue of three nickel-titanium (NiTi) rotary file systems, ProTaper Next (PTN), Hyflex CM (CM), and Hyflex EDM (EDM), in a mechanical model featuring axial movement. Ninety instruments of three different NiTi rotary file systems, PTN (size 25, 0.06 taper), CM (25, 0.06), and EDM (25/~, variable taper), were randomly divided according to a 3 × 3 factorial design and tested under dynamic immersion in a 3% NaOCl solution (1 or 5min) or without immersion, making a total of 9 groups (n = 10). Files were tested in an artificial root canal with 45° angle and 5mm radius apical curvature being submitted to back-and-forth movements until fracture. Statistical analysis was performed using two-way factorial ANOVA with Bonferroni post-hoc tests, at a significance level of 5%. Instruments were evaluated for reliability using a Weilbull approach. Regardless of the immersion treatment, PTN had on average 1200 ± 178 cycles to fracture, CM had 1949 ± 362, and EDM had 5573 ± 853, which was a significantly different (P < 0.01). The NaOCl immersion promoted a significant reduction in the mean number of cycles to fracture (P = 0.01), and was reflected in a significant reduction of the characteristic life of the instruments of the CM end EDM groups. Within this study conditions, EDM instruments performed better to cyclic fatigue followed by CM and then PTN. Immersion in NaOCl decreased the resistance to cyclic fatigue of all tested instruments, but affected more those manufactured from CM wire.