Papers by Keyword: Electro Discharge Machining (EDM)

Abstract: Emission of metallic particulate (aerosol) is an important hazard associated with the EDM process. These emissions can cause adverse health effects to the operators and has a direct impact on the environment. Therefore, concurrent investigations of the aerosol emission and machining aspects of the EDM process are essential for achieving hygienic and efficient machining. The aerosol emission from the process is directly related to the temperature at the process location. Hence, this paper first addresses a numerical model that quantifies the temperature distribution on the surface of a work piece and tool using ANSYS® 14.5. The model first calculates the temperature distribution in the workpiece material and then Material Removal Rate above the boiling temperature of workpiece and tool were estimated from the temperature profiles. Then, a model that quantifies the aerosol generated from EDM process is developed using energy balance and heat transfer equations. Validation of model has been done by comparing the results against the published experimental results obtained under the same process parameters. A good agreement was found between the experimental and numerical results. The model used in this paper can predict the level of emissions at different process locations in order to suggest suitable process conditions for green manufacturing.

Abstract: Electro discharge machining (EDM) is a most commonly used machining process among all the non-conventional machining process which removes materials via electrical and thermal energy. The primary goal of EDM is to get more material removal rate (MRR) with lower radial overcut (ROC). Normally, the responses are predicted using empirical models which are limited to only machining parameters and they do not consider the effects of work material properties on the process performance. Therefore in this study, a model has been developed including machining parameter as well as thermo-physical property of work material. In this investigation, a semi-empirical model has been established for the material removal rate (MRR) and radial overcut (ROC) by adopting the dimensional analysis technique. Dimensional analysis is a technique of dimensions and a mathematical technique that deals with the physical quantities concerned with the experiments to formulate a model for the response in terms of response control parameters as well as some physical properties of the materials. Buckingham’s л theorem is a main theorem in dimensional analysis and it is a signification of Rayleigh’s method of dimensional analysis. The theory is applied to gather each and every variable presenting the problem in a number of the dimensionless products. For this study, the thermo-physical properties viz. density, thermal conductivity and coefficient of thermal expansion and machining parameters like peak current, pulse on time, gap voltage and duty cycle are considered as input factor. AISI 304 stainless steel used as work material and Tungsten carbide is used as tool material for this investigation.

Abstract: This paper presents the investigation of minimum recast layer of zirconium oxide (ZrO₂) due to micro-EDM using EDM-3 synthetic oil as dielectric fluid and tungsten as the tool electrode with control parameters of rotational speed and gap voltage. The investigation was performed using multi-process micro machine tools DT 110. The recast layer thickness was observed using scanning electron microscope and its hardness was measured using micro-Vickers hardness tester. The hardness data were analyzed and an empirical model was developed. The optimum value for minimum recast layer hardness was 873.46 Hv with rotational speed of 395 rpm and gap voltage of 110 V.

Abstract: This study explores and demonstrates the effectiveness of employing Electro Discharge Machining (EDM) for processing ceramics particularly Metal Matrix Composite (MMC) materials. Conductive ceramics can be easily machined and non conductive ceramics can be made machinable by doping them with conductive metal particulates. In a related experimental study the effects of the concentration and size of these particulates are analyzed on the machining rate of MMC components.

Abstract: The Electro Discharge Sawing (EDS) process is a modified Electro Discharge Machining (EDM) process to obtain high material removal rates in sawing of large bar stocks and billets of high strength materials. In such a complex system as Electro Discharge Sawing (EDS) with multitude of factors affecting its performance. Taguchi approach of orthogonal arrays (OA) is best suited for the design of experiments . In the present investigation the relative influence of five factors was analyzed on typical four response parameters. An orthogonal array L₈ (2⁵) was selected for the five factors set at two levels and designated as low and high. The results show the Electrode polarity to be the most important factor with electrode positive leading to best results. The process variable parameter with highest effect is pulse current followed by pulse on time, pulse off time and voltage. Effect of work material is random depending on which thermal property is more effective out of thermal conductivity and enthalpy of melting.

Abstract: This work is aimed at optimizing the various parameters of the electro discharge machining process in order to Maximize material removal rate (MRR) and Minimize electrode wear rate (EWR) for machining silicon or resin bonded silicon carbide, which is widely used in various applications like high-temperature gas turbines, bearings, seals and linings of industrial furnaces. The five parameters being optimized are intensity supplied by the generator of the EDM machine, open voltage, pulse on time, duty cycle and pressure of flushing fluid. The polynomial models for MRR and EWR proposed by Luis, Puertas and Villa [1] in terms of the five input parameters was used for formation of the objective function. Optimization was carried out using the multi objective genetic algorithm, which is a heuristic search technique that mimics natural selection. A Pareto-optimal front was obtained using this technique, and the points lying on this front represent the set of optimal solutions for the optimization problem. The resultant Pareto– optimal front can be used to select the appropriate operating conditions depending on the specific MRR, EWR or combination requirements.

Abstract: The present study investigates the relationship of process parameters in electro-discharge diamond face grinding (EDDFG) of tungsten carbide and cobalt composite (WC-Co). The central composite rotatable design had been utilized to plan the experiments and response surface methodology (RSM) was employed for developing experimental models. Analysis on machining characteristics of EDDFG was made based on the developed models. In this study, wheel RPM, current, pulse on-time, and duty factor are considered as input process parameters. The process performances such as material removal rate (MRR) and average surface roughness (Ra) were evaluated. Analysis of variance test had also been carried out to check the adequacy of the developed regression models. The observed optimal process parameter settings are wheel RPM of 1500, current of 6.9029 A, pulse on-time of 137. 8208 µs, and duty factor of 0.79 for achieving maximum MRR and minimum Ra; finally, the results were experimentally verified. A good agreement is observed between the results based on the RSM model and the actual experimental observations. The error between experimental and predicted values at the optimal combination of parameter settings for MRR and Ra lie within 6.18% and 12.33%, respectively.

Abstract: Interaction between streamer and 316L Stainless Steel substrate in heptane with micro-gaps gives craters with a very specific shape. The role of the Marangoni forces is stressed, a phenomenon which is generally neglected in EDM processes to describe the shape of the craters.

Abstract: The development of new, advanced engineering materials and the need for precise flexible prototypes and low volume production have made Micro-EDM and important manufacturing process to meet such demands. The most important parameters in Micro-EDM are the material removal rate (MRR), the tool wear rate (TWR), accuracy and surface texture. The influence of peak current, gap voltage, pulse duration and process parameters plays important role in determining the material removal rate and tool wear rate on Micro EDM. Thus, this paper describes the development of the Micro-EDM based on the tool wear rate and material removal rate of the system using directly mounted APA 400MML actuator as the tool feed control system.

Abstract: This paper presents an experimental investigation of the machining characteristics of sintered NdFeB permanent magnet using a combination process of electro-discharge machining (EDM) with ultrasonic machining (USM). Concentration of abrasive in the dielectric fluid is changed to explore its effect on the material removal rate (MRR). MRR of EDM /USM, conventional EDM are compared, machined surface characteristics are also compared between them. It is concluded that the combination EDM/USM process can increase the MRR and decrease the thickness of the recast layer. In the combination process, an appropriate abrasive concentration can improve its machining efficiency.