Electrical Discharge Diamond Grinding Research Articles

Wheel wear behavior and its influence on grinding performance in electrical discharge diamond grinding of reaction-bonded silicon carbide

Diamond wheel wear is the greatest challenge for the high-efficiency grinding of SiC mirrors due to the need for the frequent dressing of the wheel. To realize the dressing of the diamond wheel in the process, the electrical discharge diamond grinding (EDDG) that combines conventional grinding (CG) and electrical discharge machining (EDM) was used to machine the mirror material of reaction-bonded silicon carbide (RB-SiC) considering its conductivity. However, the diamond wheel will experience quite different wear behaviors from those in the CG process due to the additional electrical discharge action in the EDDG process. As a result, different grinding performances will also be obtained. In this paper, the wheel wear behavior and its influence on grinding performance were investigated by a comparing test with the CG process in continuous EDDG of RB-SiC. The wear behavior and mechanism of the diamond wheel were investigated by a combination of morphology detection and spectra analysis. To explore the influence of wheel wear on grinding performance, the material removal rate (MRR), grinding ratio (GR), grinding force, and surface roughness were discussed based on the wear regulation of the diamond wheel varied with processing time. The result revealed that the electrical erosion was mainly responsible for the different wear behaviors and mechanisms of the diamond wheel in the EDDG process. Due to the dressing effect and material removal caused by discharge sparks, higher MRR, lower GR, lower grinding force, and lower surface roughness were obtained in the EDDG process.

A REVIEW ON ELECTRICAL DISCHARGE GRINDING: CURRENT STATUS AND FUTURE PERSPECTIVES

Electrical discharge machining (EDM) is widely applied for machining difficult-to-cut materials in mold and die industries. However, the major limitations associated with the EDM are low productivity and poor surface integrity of the machined surfaces. In recent years, several developments have been applied to overcome such limitations of EDM. Electrical discharge grinding (EDG) is a hybrid machining process that simultaneously involves the spark erosion action of EDM and the mechanical abrasion action of the grinding wheel for the material removal purpose. The rotating motion of the grinding wheel also contributes to the easy removal of debris particles, thereby improving the material removal. It is evident from the literature that the rotating motion of the grinding wheel enhances the flushing mechanism resulting in better performance of the process. This paper aims to present a comprehensive review of the research carried out in EDG, highlighting the result of the experimental, modeling, and optimization techniques applied in this area. Initially, the background of EDM and the need for hybrid EDM processes have been presented. Then, a few hybrid EDM processes have been discussed, addressing their advantages and limitations. Further, the concept of EDG and electrical discharge diamond grinding (EDDG) has been discussed, along with the classification of the EDDG process. Finally, this paper explores the current research status and future research perspective in the area of EDG and EDDG processes.

Research of the dependence of geometric parameters of holes on electroerosive grinding modes with a changing polarity of electrodes

In this paper are presented the results of electrical discharge diamond grinding with with difference polarities for processing various materials and calculates geometric parameters of erosion holes. The purpose of the study is to determine the volume of holes during electrical discharge diamond grinding using the mathematical method of planning experiments. The experimental plans is a combination of statistical theory and mathematical model, which is very useful in the modelling and analysing the technical problems. As a result of experimental studies, a mathematical model of the volume of holes from electrical modes of the process of electrical discharge diamond grinding was built. The mathematical formula of geometric parameters of holes obtained can be used to determine the volume of holes for different electrical quantities of discharge diamond grinding. It is found that the most significant factors that affect the geometric parameters of holes are the voltage of the igniting pulse and the pulse duration. The dependence of electrical parameters on the hybrid grinding process is investigated. There is a certain volume of holes, at which the discharge acts most efficiently, and the process performance is the most optimal. During the operation of the pulse generator, it is preferable to maintain a certain value of geometric parameters of holes, which results in an unhindered release of metal, since the effect of electrical erosion increases.

Predicting the material removal rate during electrical discharge diamond grinding using the Gaussian process regression: a comparison with the artificial neural network and response surface methodology

Machine learning approaches can help facilitate the optimization of machining processes. Model performance, including accuracy, stability, and robustness, are major criteria to choose among different methods. Besides, the applicability, ease of implementations, and cost-effectiveness should be considered for industrial applications. In the current study, we present the Gaussian process regression model to predict the material removal rate during electrical discharge diamond surface grinding of Inconel-718. The model uses descriptors that include the wheel speed, current, pulse-on-time, and duty factor. The model is simple and manifests high accuracy and stability, which contributes to fast material removal rate estimations. By combining the optimization results from the Taguchi method and GPR approach, it is expected that more quantitative data can be extracted from fewer experimental trials at the same time.

Modelling, Investigation of Process Responses, Surface Assessment and Parametric Optimization in Powder Mixed Electrical Discharge Diamond Grinding of TI6AL4V Utilizing Grey-Based Taguchi Approach

Modelling, Investigation of Process Responses, Surface Assessment and Parametric Optimization in Powder Mixed Electrical Discharge Diamond Grinding of TI6AL4V Utilizing Grey-Based Taguchi Approach

Surface and subsurface damage of reaction-bonded silicon carbide induced by electrical discharge diamond grinding

Reaction-bonded silicon carbide (RB-SiC) ceramic, one of the best candidates for large optical mirrors, is difficult to machine because of its high hardness and brittleness. A hybrid process called electrical discharge diamond grinding (EDDG) exhibits potential for improving the machinability of RB-SiC by combining electrical discharge machining (EDM) and diamond grinding. However, this hybrid process leads to damages that differ from those in conventional processes owing to the simultaneous actions of EDM and diamond grinding. In the present study, surface and subsurface damages induced by the interactions between EDM and diamond grinding during the EDDG of RB-SiC were examined. The effect of the discharge energy was considered. The surface and subsurface topographies and microstructures were characterized via scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy. The EDM and grinding zones exhibited distinctive surface topographies and different dominant material removal mechanisms. An increase in the discharge energy facilitated ductile removal of the material and decomposition of SiC. Thus, a thinner subsurface damage layer was obtained compared with that in the less-thermally affected zone. The decomposed C and material migration tended to increase with the discharge energy. Owing to the interactions between EDM and diamond grinding, the subsurface was a mixture of amorphous/crystalline C, polycrystalline/nanocrystalline SiC, and a crystalline SiC matrix.

Experimental investigation on electrical discharge diamond grinding of RB-SiC ceramics

The reaction-bonded silicon carbide (RB-SiC) ceramics are very difficult to be machined by conventional techniques. In this work, a hybrid process termed electrical discharge diamond grinding (EDDG) was applied to the precision grinding of RB-SiC ceramics considering its weak electrical conductivity. Focus of investigation was especially placed on the effects of grit sizes and polarities of grinding wheel on the surface quality. The machined surface texture and roughness were measured by confocal scanning laser microscope. The surface texture topography and cross-section profile at different grit sizes and polarities were analyzed. The results show that the dominant state of grinding or EDM decides surface texture of machined surface and consequently affects the surface roughness. The surface morphology and subsurface damage were measured by scanning electron microscopy and energy dispersive spectrometer (EDS). The influence of grit sizes and polarities of grinding wheel was focused on the resolidified zone of the machined surface. The material migration phenomenon was found. The subsurface damage was also analyzed by detecting the polished cross-sections, and the depth of subsurface was determined by analyzing the element distribution with EDS spectrums. At last, the formation mechanism of machined surface and the effects of grit sizes and polarities of grinding wheel on machined surface quality were discussed from the viewpoint of discharge energy based on EDM theory.

Experimental investigations on electrical discharge diamond peripheral surface grinding (EDDPSG) of hybrid metal matrix composite

In this paper, authors have endeavored to develop an experimental setup of Electrical Discharge Diamond Peripheral Surface Grinding which is a configuration of Electrical Discharge Diamond Grinding process. The machining performance characteristics were experimentally studied using the developed experimental setup during machining of a challenging material Al/SiCp/B4Cp hybrid metal matrix composite. Gap current, on-time, off-time, abrasive grit number, speed of wheel, and table speed were input process parameters considered. The influence of input process parameters were experimentally investigated on material removal rate and surface roughness using one parameter at a time approach. Scanning Electron Microscopy was used to study the surface texture and recast layers on machined surface. The surface finish is better achieved at a critical pulse off-time with appropriate declogging of diamond wheel. A specific abrasive grit size is suitable for better removal of thermal infested surface deteriorations with minimal marks of grinding traces. The presence of shallow craters and negligible thickness of recast layers on machined surface substantiate the potential capability and applicability of developed EDDPSG experimental system.

Performance study of Electrical discharge diamond face surface grinding (EDDFSG) on hybrid metal matrix composite

Hybrid machining techniques are effective means for machining of difficult-to-cut, electrically conductive hard and brittle materials. In the present work, performance characteristics of newly developed Electrical discharge diamond face surface grinding were experimentally studied during machining flat surfaces of a difficult-to-cut hybrid metal matrix composite, which is a new configuration of electrical discharge diamond grinding. Gap current, on and off time are the spark related parameters as well as grinding related parameters such as abrasive grit size, RPM of wheel, and table speed are considered as input process parameters. The role of input process parameters was investigated in machining performance such as MRR and R a during electrical discharge diamond face surface grinding of Al/SiCp/B4Cp hybrid metal matrix composite. Scanning electron microscopy was also used to study the recast layers and surface texture of machined surface. Better surface finish with reduced recasts and higher MRR evince the potential applicability of the process.

Effects of Electricity Parameters on Surface Quality of Reaction Bonded Silicon Carbide Ceramic with Electrical Discharge Diamond Grinding

With some conductivity and low grinding affectivity, a hybrid machining process termed electrical discharge diamond grinding (EDDG) is applied to the precision machining of reaction bonded silicon carbide (RB-SiC) ceramic. As there is electrical spark in the hybrid machining process, the electrical parameters are varied to explore their effects on the surface quality of RB-SiC ceramic with EDDG. In this paper, the experiments of different polarity and gap voltage with EEDG were investigated, and the microstructure and surface roughness on the machined surface of RB-SiC ceramic were analyzed. The surface morphology and micro-cracks were examined with a scanning electron microscope, and the surface roughness was measured with a confocal scanning laser microscope. It is found that surface roughness initially increases and then decreases with increase of the gap voltages and is higher with negative polarity than that with positive polarity. The micromorphology Micro-cracks were observed on the surface machined and are outstanding in re-solidified zone with EDDG.

Experimental investigations on electrical discharge diamond face surface grinding (EDDFSG) of hybrid metal matrix composite

ABSTRACTStudies on the applicability of various configurations of Electrical Discharge Diamond Grinding (EDDG) are facing many challenges during the machining of advance difficult-to-machine materials. In the present paper, description of a new configuration of EDDG, called the Electrical Discharge Diamond Face Surface Grinding (EDDFSG) system, has been discussed. Experimental investigations have been made using the one parameter at a time (OPAT) approach to study the effect of gap current, on-time, off-time, abrasive grit number, RPM of wheel and table speed on the material removal rate (MRR) and surface roughness (Ra) during EDDFSG of hybrid metal matrix composite (MMC). Surface texture and recast layers of the machined surface have also been studied using Scanning Electron Microscopy (SEM). Higher MRR with better surface finish and hardly seen recast layers on the machined surface demonstrate the potential applicability of the process for machining flat surfaces made of such challenging and complex materials.

Modelling and multi-objective optimisation of EDDG process using hybrid ANN-GA approach

It has been found that wheel wear rate (WWR) and surface finish is adversely affected in order to improve the material removal rate (MRR) in electrical discharge diamond grinding (EDDG) process. Therefore, simultaneous optimisation of above three responses is always desired. This research paper presents the modelling and multi-objective optimisation of EDDG using AI-based hybrid ANN-GA approach. The effect of wheel grit size has also been considered along with electrical parameters such as peak current, pulse-on time and pulse-off time. The significant control parameters for different responses have been found and effect of their variation has been discussed. The developed ANN models for different responses have been found reliable with negligible prediction errors. The optimisation results show considerable improvement of 97% in MRR with marginal increase in WWR and surface roughness.

电火花机械复合磨削反应烧结SiC陶瓷的表面特征

电火花机械复合磨削反应烧结SiC陶瓷的表面特征

Development and Experimental Study of Surface-Electrical Discharge Diamond Grinding of Al–10 wt%SiC Composite

As silicon carbide possesses small fracture toughness, it is difficult to grind because it leads to cracking. Metal matrix composites can be machined using electrical discharge machining (EDM) but the process is slow. Electrical discharge diamond grinding (EDDG), which consists of diamond grinding and EDM with a rotating disk which enhanced material removal rate (MRR) and produce better surface finish. This paper describes the machining characteristic of Al–SiC composite using EDDG in surface grinding configuration which is called as surface-electrical discharge diamond grinding (S-EDDG). A chain of experiments were performed on S-EDDG set up by mounting newly self designed and fabricated set up on conventional die sinking EDM machine using the approach of one parameter-at-a-time concept. Surface roughness (Ra) and MRR are taken as output parameters as both are important outcome in the manufacturing process and they materialize a major division in the manufacturing system. The effects of current, wheel speed and depth of cut is analyzed on MRR and Ra. Finally, optimization have been done through weighted principal component analysis.

Machining Performance of Slotted-Electrical Discharge Diamond Face Grinding of Al/SiC/Gr Composite

Electrical discharge diamond grinding (EDDG) is a well-known process for machining of electrically conductive hard and brittle materials. Even though, EDDG process suffers with several drawbacks such as loss of diamond particles without wear, high wheel wear, accumulation of debris into gap, abnormal arcing, etc. The aim of this study is to minimize the drawbacks of EDDG process with an alternative application of spark erosion and abrasive abrasion actions. Such developed process is knows as slotted-electrical discharge diamond grinding (S-EDDG) process. The performance of developed process was tested on face grinding mode of the S-EDDG during machining of the aluminum–silicon carbide–graphite (Al/SiC/Gr) workpiece. The role of current, pulse on-time, pulse off-time, wheel rotation per minute (RPM), and abrasive grit number has been investigated on material removal rate (MRR) and average surface roughness (Ra). It has been observed that higher wheel RPM gives higher MRR with better surface finish due to increase in flushing efficiency.

Modelling and optimisation of material removal rate and surface roughness in surface-electrical discharge diamond grinding process

Metal matrix composites (MMCs) can be machined using electrical discharge machining (EDM) but the process is found slow. Electrical discharge diamond grinding (EDDG), which is a hybrid machining process (HMP) comprising of diamond grinding (DG) and electrical discharge grinding (EDG), has been found a viable machining method which enhances MRR and produce better surface finish. During EDDG, abrasive grains eradicate the non-conducting material particles of MMCs, and spark discharges thermally softened the surrounding binding material. In the present work, an attempt has been made for modelling of EDDG in surface grinding mode for outputs MRR and average surface roughness (Ra) and inputs wheel speed, depth of cut, workpiece speed, pulse on-time, current and duty factor. Experiments were carried out on a newly self-developed surface grinding setup for EDDG on a die sinking EDM machine for Al-10wt.%Al2O3 composite. Finally, weighted principal component (WPC) is proposed for optimising the machining parameters.

Experimental study of erosion and abrasion based hybrid machining of hybrid metal matrix composite

Machining of metal matrix composites (MMCs) are still a challenge for manufacturing industries. Among various machining processes, electrical discharge machining (EDM) and diamond grinding (DG) are more acceptable processes for machining of the MMCs. In this paper, a new compound wheel (CW) is developed in such a way that both processes (EDM and DG) occur in alternate way due to the rotation of wheel. The performance of erosion and abrasion based hybrid machining (EAHM) process has been tested on hybrid aluminium-silicon carbide-graphite (Al/SiC/Gr) composite in terms of material removal rate (MRR) and average surface roughened (Ra). The experiments have been conducted on EDM machine with application of CW for effective spark erosion and abrasive abrasion machining. The effects of pulse current, pulse duration, pulse interval and wheel speed on MRR and Ra has been experimentally investigated and discussed.

Modeling and Prediction of Material Removal Rate and Surface Roughness in Surface-Electrical Discharge Diamond Grinding Process of Metal Matrix Composites

Material removal rate (MRR) and surface roughness (SR) have always been a big deal during any manufacturing process. Metal matrix composites (MMCs) can't be effectively machined by conventional grinding and process is found to be slow when machined by electrical discharge machining (EDM). Present work is an attempt for modeling of electrical discharge diamond grinding (EDDG) in surface grinding mode which is known as the surface-electrical discharge diamond grinding (S-EDDG) process. The technique used for modeling the process is artificial neural network (ANN) through traingdx training function. Experiments were carried out on newly developed and fabricated surface grinding setup for EDDG on a die sinking EDM machine for Al-10wt%SiC and Al-10wt%Al2O3 composite workpiece. Prediction through modeling of S-EDDG process indicates that MRR increases as pulse current, wheel speed, workpiece speed, depth of cut increases, and decreases with increase in duty factor. The Ra increases with increase of current, duty factor, depth of cut, and workpiece speed, and decreases with increase in wheel speed.

Simultaneous Optimization of Multiple Quality Characteristics in Electrical Discharge Diamond Cut-Off Grinding (EDDCG)

This paper presents the simultaneous optimization of multiple quality characteristics (Material removal rate and Average surface roughness) using Taguchi method for electrical discharge diamond cut-off grinding (EDDCG) during machining of cemented carbides material. The experiments are carried out on a self-developed electrical discharge diamond grinding setup in cut-off mode, In the present work four input parameters ( current, pulse on-time, duty factor and wheel RPM ) were selected in which each parameter was at three levels. The total degree of freedom (dof) has been calculated without considering the effects of interaction among the different control factors. Based on design of experiments (DOE), a standard L9 orthogonal array (OA) was taken for experimentation. The result shows the considerable improvement of 13.999dB in multiple S/N ratio as compared to initial condition. Also, the comparison of results from single and multi-objective optimization has been presented.

The use of diamonds synthesized in the Fe-Si-C growth system for grinding tool applications

The paper summarizes the findings of the investigation into properties of diamond powders grown in the Fe-Si-C system. Diamond is synthesized using Fe-Si with a silicon content of the alloy being 5–7 wt %. The influence of the ferrosilicon amount in synthetic diamonds of grade AS6 on the specific diamond consumption in the process of diamond and electrical discharge diamond grinding.