Papers by Keyword: Electrical Discharge Machining (EDM)

Abstract: This study investigates the performance of Electrical Discharge Machining (EDM) on magnesium alloy grade AZ91 using a graphite electrode, with a focus on optimizing the material removal rate (MRR) and electrode wear ratio (EWR). The machining parameters such as current, on-time, and duty factor were systematically varied and assessed using the Taguchi method with an L9 orthogonal array design. The results identified current and on-time as significant factors influencing both MRR and EWR. Higher current values led to increased MRR, enhancing material removal efficiency, but also resulted in greater electrode degradation. Similarly, increased on-time durations significantly impacted MRR and EWR, indicating that prolonged exposure to discharge conditions can improve material removal while contributing to higher electrode wear. Conversely, the duty factor did not show a statistically significant impact on either MRR or EWR within the experimental conditions of this study.

Abstract: The present paper concerns with studying the high complexity nature of the EDM multiple discharge analysis transformed into a feasible solvable mathematical model for the die steel workpiece type AISI D2, the copper and graphite materials electrodes, and the kerosene dielectric by setting the Transient Thermal and the Multiphysics analyses domain loads models using the ANSYS 15.0 finite element analysis. Two load steps modeled the entering setting time analysis, six sub-periods setting time cycle, four heating, and two cooling periods, six transient temperature values, and four transient thermal convection models. The radius spark (discharge channel), the total number of discharges sparks, the total heat power generation, the absorbed heat flux fractions by the electrodes, the workpieces and kerosene fluid dielectric, the heat-affected zones (HAZ), the hard white recast layer thickness (WLT) and properties, the workpiece fatigue safety factor and life after EDM machining were determined and simulated. The thermal model errors compared with theoretical calculations and a modeled predicted equation were also deduced and verified. The experimental results evinced that the maximum total heat flux generated using the graphite material electrodes is (2.619E+009 W/m2) which is higher than when using copper material electrodes by (82.4%), while the minimum value of the white layer thickness (WLT) after EDM machining using graphite tool electrodes is (8.34 μm), which it gives an improvement comparing with using of copper tool electrodes by (40.0%). The macrographic and microstructure evaluation manifest that the discharge spark craters sizes when using graphite tool electrodes reached their sizes. The maximum fatigue stresses and fatigue safety factor when using copper tool electrodes are (240 MPa) and (0.89) which is higher by a value of (3.35%) and (3.45%) comparing with the using of graphite electrodes, respectively.

Abstract: Electrical discharge machining (EDM) is a non-conventional process that is widely used for high-precision machining, complex product shapes, and high hardness materials. The EDM mechanism is based on the thermoelectric energy between the electrode and the workpiece. The EDM process has many parameters that can be adjusted, such as discharge current, voltage, pulse on time, pulse off time, electrode polarity, workpiece material, electrode material, dielectric fluid type, flushing pressure, flushing direction and flushing method. This study aims to find the parameters of the EDM process to optimize its productivity indicated by material removal rate (MRR) and its quality indicated by surface roughness of SS-316 material. The varied parameters were discharge current, pulse on time, and pulse off time with 3 levels for each parameter. Fractional orthogonal array L9 were applied for three 3-level variables. Performance fluctuation due to noise factors were simply approximated by 3 replicating measurements to estimate mean and standard deviation. Taguchi S/N ratio were adopted as robustness index for the optimum parameter design. The optimization results show that the discharge current 30A, pulse on time 100μs, and pulse off time 8μs are the optimum for MRR. As for surface roughness, the discharge current is 10A, pulse on time is 100μs, and pulse off time is 8μs. The only different of EDM parameter for optimum MRR and optimum Ra is discharge current.

Abstract: The present work reports the influence of various Electric-Discharge Machining (EDM) process parameters on the surface morphology and EDM characteristics of thixoformed A356-5TiB₂ in-situ composites. The important EDM parameters such as pulse current, pulse-on time, Duty Cycle, etc. on Surface morphology and Material removal rate of the thixoformed A356-5TiB₂ in-situ composites have been investigated. Further, the machining parameters were optimized using Fuzzy-logic and grey relational analysis approach. The effect of EDM parameters and their interactions on the erosion behavior of A356-5TiB₂ in-situ composites on various aspects of surface integrity and Material Removal rate (MRR) is reported. The surface integrity during EDM was characterized by Scanning Electron Microscope and analyzed from the machinability point of view. Thus, this work is an attempt to study the machinability behavior of thixoformed A356-5TiB₂ in-situ composites.

Abstract: Electropolishing is an attractive method for surface smoothing of cardiovascular stent. This study investigated the effect of times of electropolishing on the surface characteristics both are upper surface and surface of the strut of cardiovascular stent after the by die sinking electrical discharge machining (EDM). The observed surface characteristics of the strut were recast layer, surface roughness and brightness. The weight analysis, and the reduction of the width strut were conducted. The recast layer was analyzed by optical microscope qualitatively, the surface roughness was measured by surface texture measuring instrument, the weight analysis and the reduction of width strut were calculated. The stent was made from steel AISI 316 L. The times which were used in the electropolishing were 3 minutes, 7 minutes, and 11 minutes. The experimental results show that the time for smoothing and brightening of stent at room temperature and low voltage 5 V is 7 minutes. The times affect the upper and EDM surface roughness, the weight of stent and the width of strut. The results show that increasing of times, than the value of surface roughness, the weight of stent and the width of strut will decrease, and vice versa. The average surface roughness of EDM surface after electropolishing is in the range of 3.49 – 1.62 µm. The average surface roughness of upper surface after electropolishing is in the range of 0.55-0.22 µm. The weight analysis show that the loss of weight is in the range of 0.12-1.12 %, and the reduction of width strut is in the range of 11.02 – 69.3 %.

Abstract: With the demand of modern cutting technology for ‘high efficiency, precise, flexibility and green manufacturing’, polycrystalline diamond materials as cutting tools have been widely used in automobile, aerospace and non-metal processing. Electro-spark erosion is one of the most effective ways to machine polycrystalline diamond materials. Single pulse discharge is one of the research foundations of micro-EDM. Using 2 micron granularity polycrystalline diamond as experiment material, the influence of single pulse discharge technology on the removal efficiency of materials was studied, such as pit radius, pit depth and radius-depth ratio, etc. The experimental results show that, with the extension of the pulse duration, the radius of the discharge pit begins to increase rapidly, then slowly increases, and finally to slow down; while the radius of thermal influence zone increases rapidly and then continues to increase slowly. With the extension of pulse duration, the ratio of pit depth to radius changes within the range of 0.05 ~ 0.25, which shows a downward trend basically.

Abstract: The paper deals with the wear of tool electrodes for Die Sinking EDM. In the experiment were used the electrodes of copper and graphite. The workpiece material was steel EN43CrMo4. For the assessment the effects of each parameter was used the statistical method Design of Experiments (DOE). Assessed input factors were the peak current, pulse on-time, pulse off-time, and the electrode material. The result of the effects of each input factors was tool electrode wear. For calculating the relative wear of electrodes was used the percentage of the ratio of the electrode and the workpiece weight. The results show that the expression of the relative wear in practice can be described as a method unusable due to the absorption of the graphite electrode used in the experiment.

Abstract: Geometrical precision machined surface is generally understood as mainly precision shape, orientation, location and run-out. As a rule, it is measuring the appropriate deviations from the nominal surface. The geometric size of this deviation from the nominal surface can in practice affect the conventionally measured value for the dimension and the dimension whilst maintaining the required tolerance. Because the WEDM technology is among the most accurate technology, the small final geometric accuracy deviation has also a negative impact on the final quality of the machined surface. The paper aimed to describe errors geometrical precision of machined surface which occurs in wire electrical discharge machining (WEDM) and quantify their scope.

Abstract: The paper describes the basic physical regularities of material removal in Electrical discharge machining (EDM) of tool steel. One of the parameters, that material removal regularities quite accurately identifies, is the tool wear rate (TWR). This parameter, however, describes only the regularities concerning the tool electrode wear. More complex parameter for assessing regularities of material removal in EDM is thus electrode wear ratio (EWR). This parameter, except the size of the wear of the tool electrode, also describes the size of the workpiece material removal. Research on material removal was carried out on samples made out of tool steel EN X32CrMoV12-28 using Cu-ETP electrode EN CW004A. Aim of this paper was also based on the selection of main process parameters that significantly influence the material removal in EDM to define the individual specifics with regard to minimizing EWR.

Abstract: The present work attempts to study the effect of important process parameters on material removal rate in electro-discharge machining of nickel-based superalloy. Experiments based on orthogonal array were conducted. Contents of peak current, pulse on time, duty cycle, and servo voltage were the main factors, and each factor was endowed three levels. Range analysis was used to investigate the orthogonal test on material removal rate, and a set of appropriate parameters were found. Confirmation test was conducted to validate the analysis and it can be seen that the predicted values show good agreement with the experimental results. The outcome of the present research work will be a considerable aid to industries for efficiency improvement in processing using EDM.