A COMPARATIVE STUDY ON MATERIAL REMOVAL RATE BY EXPERIMENTAL METHOD AND FINITE ELEMENT MODELLING IN ELECTRICAL DISCHARGE MACHINING (original) (raw)
Related papers
ARTICLE INFO ABSTRACT Generally the non-convectional machining processes use thermal source of energy for the material removal. Among them Electrical discharge machining (EDM) or spark erosion machining is most important one. The important process parameters in this technique are discharge pulse on time, discharge pulse off time current and gap voltage. The values of these parameters significantly affect such machining outputs as material removal rate. In the present research, an axisymmetric thermo-physical finite element model for the simulation of single sparks machining during electrical discharge machining (EDM) process is exhibited and the model has been solved by using ANSYS 11.0 software. A transient thermal analysis assuming a Gaussian distribution heat source with temperature-dependent material properties has been used to investigate the temperature distribution on the surface. Material removal rate was calculated for multi-discharge machining by taking into considerations...
Thermal-electrical modelling of electrical discharge machining process
2007
Non-traditional machining has grown out of the need to machine exotic engineering metallic materials, composite materials and high tech ceramics having good mechanical properties and thermal characteristics as well as sufficient electrical conductivity. Electric Discharge machinery developed in late 1940's has been accepted worldwide as a standard process in manufacturing and is capable of machining geometrically complex or hard material components, that are precise and difficult-to-machine such as heat treated tool steels, composites, super alloys, ceramics, hastalloys, nitralloy, nemonics, carbides, heat resistant steels etc. being widely used in die and mold making industries, aerospace, aeronautics and nuclear industries The thermal erosion theory is the most accepted mathematical model for evaluating material removal from electrodes during EDM process. It postulates that the process involves melted electrode and its evaporation by the discharge energy dissipated on electrode surface. Part of the melted and evaporated material is then ejected from electrode by force of different natures. Keeping this in view, the present work has been undertaken to generate a thermal-electrical model for sparks generated by electrical discharge in a liquid media and to determine the temperature distribution of tool and work piece. For a single discharge test, copper and En-19 was used as specimens. The amount of heat dissipated varies with the thermal-physical properties of the conductor. The model is developed by using ANSYS software. ANSYS uses the finite-element method to solve the underlying governing equations and the associated problem-specific boundary conditions. Material Removal Rate, Surface Roughness and the maximum temperature reached in the discharge channel is determined.
Thermal and mechanical numerical modelling of electric discharge machining process
Communications in Numerical Methods in Engineering, 2008
In electric discharge machining (EDM), the heat gradients caused by the electric discharge create a nonuniform local thermal expansion on the level of the surface layers of machined materials from where genesis of thermal stresses takes place. These thermal stresses, if exceeding yield stress, can remain and become residual after the cooling of the part. The modelling of these phenomena, during the heating by the electric discharge and the cooling by the dielectric liquid, requires a heat transfer model, the material behaviour identification, a thermo-mechanical model for the thermal and the residual stress models. This paper presents numerical results concerning the temperature distribution, the thermal and residual stresses of a stable steel material (AISI316L) machined by EDM. Comparison of numerical results with experimental data and numerical results from the literature shows good agreement and is hence quite satisfactory.
Journal of Materials Engineering and Performance, 2020
Electrical discharge machining (EDM) is a non-conventional method of machining hard materials with intricate shapes. Near-dry electric discharge machining (ND-EDM) is an advanced method of EDM which is eco-friendly and is more efficient in terms of material removal rate (MRR) than traditional EDM. In this research, an approach has been made to perform a new electrical discharge machining operation on EN-31 steel which utilizes metallic powder as an additive along with a gaseous dielectric (for example air) in ND-EDM. This advanced method of machining is known as powder mixed near-dry EDM. This study involves modeling for output process parameter-Material Removal Rate. The mathematical model was developed using the approach of Gaussian heat distribution. FEM modeling was done on ANSYS WORKBENCH 16.0 module. The experiments were performed and comparative study was done between the results obtained by modeling and experiments. The maximum experimental MRR was 7.68 mm 3 /min, and the error percentage between experimental, mathematical and FEM was under 30%. It was concluded that the modeling was done successfully and results obtained do comply with the methodology of the research.
2009
Electrical Discharge Machining (EDM) is a non-conventional machining process whose thermoelectric nature makes it suitable for the machining of any material, regardless of its hardness and of its brittleness, as long as it conducts electricity. Despite EDM is a popular process in industry, the fact that it involves phenomena of very distinct natures (electrical, thermal, chemical and metallurgical) together with the difficulty inherent to the experimental study of the discharge process, there is a lack of scientific knowledge about it. The present work aims to help in this sense, providing a novel modeling tool capable of simulating discharge superposition, which allows the prediction of surface topographies and temperature fields due to discharges. Based on the comparison between results of simulations (material removal rates and surface topographies) and experimental measurements the discharge process can be characterized using an inverse method. Here, the basis of the developed model will be presented, together with the methodology employed to find out the parameters which define discharge properties. Results obtained with this inverse method have been included.
Study on Electrical Discharge Machining and Effect of its Parameters
The Electrical Discharge Machining (EDM) is one of the most common and most accepted non-traditional machining processes used in tooling industries. EDM is an important manufacturing method developed in 1940's. The forming tools to produce plastic molding die casting, forging dies etc. It is an electro-thermal process and is based on eroding effect of an electrical spark on both electrode and work piece. It is a thermal erosion process where metal removal takes place by series of recurring electrical discharges between cutting tool acting as an electrode and a conductive work piece in the presence of a dielectric fluid. The dielectric fluid will be flooded in a small gap of about 0.01mm to 0.5mm. This discharge occurs in voltage gap between the electrode and work piece. Currently, non-traditional process possess virtually unlimited capabilities except for volumetric material removal rates, for which great advances here been made in past few years to increase the cost effectivene...
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2015
Existing single spark models are subjected to too simplistic assumptions such as uniform or point heat source, constant plasma radius, invariable materials properties and constant surface temperature during discharge making them far from reality. In this study, more realistic assumptions including Gaussian type distribution of spark heat flux, temperature dependent materials properties, latent heat of melting and expanding plasma channel with pulse current and time have been made to establish a comprehensive modeling platform. The ABAQUS FEM software has been used to simulate the mechanism of crater formation due to a single discharge. The non-uniform thermal flux was programmed through the DFLUX subroutine. The simulation results show that the temperature of work piece decreases as the discharge time increases while the volume of melted and evaporated material increases. A specially designed single spark experimental set-up was developed in laboratory to carry out a few single spark tests for verification purposes. The obtained craters morphologies were examined by optical microscopy and scanning profilometer. It has been shown that the present approach outperforms other previously developed thermal models with respect to cavity outline and size possessing the maximum confirmation errors of 18.1% and 14.1% in predicting crater radius and depth, respectively. Parametric analysis reveals that the melting boundary moves onward by increasing discharge current, whereas it moves back prolonging discharge time. Finally, a closer proximity to experimental material removal rates than those predicted by analytical approach has been recognized which confirms its more precise generalization capabilities towards the real state EDM process.
Numerical study of thermal aspects of electric discharge machining process
International Journal of Machine Tools and Manufacture, 2006
This paper presents numerical results concerning the temperature distribution due to electric discharge machining process. From these thermal results, the material removal rate and the total roughness are deduced and compared with experimental observations. It is shown that taking into account the temperature variation of conductivity is of crucial importance and gives the better correlations with experimental data. q
Determination of Material Removal Rate in Electro Discharge Machining through Copper Electrode
International Journal for Research in Applied Science & Engineering Technology, 2021
In the present manufacturing area, Electro discharge machining is one of the most emerging area for production of various components. Electro-discharge machining (EDM) is a thermoelectric process which utilizes the heat energy generated by spark to remove the material from the surface of work-piece. In the EDM process material removal takes place from both tool material and work-piece. The material removal rate depends upon the work-piece material, tool material and machining variables. Materials having low melting point having high material removal rate and hence lower surface finish. It is found that with increase in pulse current and constant pulse-on-time material removal rates increases but it affects the surface finish of material. EDM efficiency can be increased by supplying the oxygen gas between the spark gap and stack removal rate can be increased by increasing the volume of discharge crater and regular occurrence of discharges. The only limitation in the EDM is that the work-piece and the tool material both should be electrically conductive. The electrical energy converted into the thermal energy by series of the electric discharge that occurred between the work-piece and tool which are immersed into the dielectric fluid. The plasma channel is generated by thermal energy between anode and cathode. The plasma channel is generated at a temperature range of 8000-1200°C. Sometimes it is nearly about 20,000°C which is too high and can machine any material. The location of electric spark which is generated by heat energy is determined by the narrowest gap between the tool and work-piece. Duration for each spark is very short. The frequency for each spark is high as thousands sparks per second. However, spark radius is very small and the temperature in the spark zone is very high. This temperature of spark is capable for partially vaporize and melting the material from both the work-piece and tool material. The volume of material removal per discharge from the work-piece depends upon the specific applications and it is ranging from 10-6-10-4 mm 3. The material removed from the surface of work-piece is in the form of craters which is all overspread on the work-piece. Craters sizes are highly influenced by the value of current. Machining of Titanium alloy is carried out using EDM process. This paper presents evaluation and study of Material removal rate of titanium alloy using copper electrode in electro discharge machining process.
International Journal of Machine Tools and Manufacture, 2004
The development of new, advanced engineering materials and the need for precise and flexible prototypes and low-volume production have made the wire electrical discharge machining (EDM) an important manufacturing process to meet such demands. This research investigates the effect of spark on-time duration and spark on-time ratio, two important EDM process parameters, on the material removal rate (MRR) and surface integrity of four types of advanced material: porous metal foams, metal bond diamond grinding wheels, sintered Nd-Fe-B magnets, and carbon-carbon bipolar plates. An experimental procedure was developed. During the wire EDM, five types of constraints on the MRR due to short circuit, wire breakage, machine slide speed limit, and spark on-time upper and lower limits are identified. An envelope of feasible EDM process parameters is generated for each work-material. Applications of such a process envelope to select process parameters for maximum MRR and for machining of micro features are discussed. Results of Scanning Electron Microscopy (SEM) analysis of surface integrity are presented.