Evolution of White Layer and Residual Stress in Electrical Discharge Machining

2021 ◽  
Author(s):  
Guisen Wang ◽  
Fuzhu Han ◽  
Liang Zhu
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Layer Thickness ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
White Layer ◽  
Machining Parameters ◽  
Discharge Energy ◽  
White Layer Thickness

Abstract White layer and residual stress are the main reasons for the decrease in fatigue life of electrical discharge machined samples. Therefore, it is important to research the evolution of the white layer and residual stress in electrical discharge machining and explain the influence mechanism of machining parameters on them. In this study, the surface topography, white layer thickness, and residual stress of electrical discharge machined samples under different processing parameters were evaluated. The results indicated that surface roughness, white layer thickness, and residual stress increased as the discharge current (I) and pulse-on time (ton) increased. However, when the ton was short, the effect of I (≤ 9.8 A) on surface roughness is not very obvious. When the discharge energy is similar, surface roughness is high under high I conditions. When the discharge energy is similar and low, the average thickness of the white layer is thin under the low I. The effect of I on surface residual stress was greater than that of the ton. The I and ton affect the white layer and residual stress by affecting the amount of melting and removal of the materials. These results were demonstrated that the input process of discharge energy has an important influence on residual stress and the white layer. Therefore, under the premise of ensuring the processing requirements, they can be controlled by selecting the appropriate combination of the ton and I to improve the fatigue life of the workpiece.

Correlation of surface roughness and recast layer thickness in electrical discharge machining

2015 ◽  
Vol 231 (3) ◽  
pp. 414-424 ◽  
Author(s):  
Yakup Yildiz ◽  
Murali M Sundaram ◽  
Kamlakar P Rajurkar ◽  
Ahmet Altintas
Keyword(s):  
Surface Roughness ◽  
Layer Thickness ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
White Layer ◽  
Processing Technique ◽  
Recast Layer ◽  
Image Processing Technique ◽  
Recast Layer Thickness ◽  
Two Parameters

Electrical discharge machining (EDM) is an extensively used method in the machining of electrically conductive materials. Recast or white layer formation is undesirable, but inevitable, result of EDM and needs to be understood and accurately determined to efficiently perform post-treatment processes for removing the recast layer caused by EDM process. In this study, recast layer thickness and surface roughness data obtained from experimental study were analyzed and a correlation between these two parameters has been established. Image-processing technique has been used for obtaining of recast layer thickness data. It was observed that the correlation between recast layer thickness and surface roughness increases remarkably with the increase of working current and pulse time. The correlation obtained in this study has the potential to predict the recast layer thickness on spark-eroded surfaces from simple surface roughness values instead of using the prevailing time-consuming and tedious etching and polishing method. The possible approximation of the recast layer thickness using a thermal model is also discussed.

scholarly journals Experimental Study on the Influence of Machining Conditions on the Quality of Electrical Discharge Machined Surfaces of aluminum alloy Al5052

Machines ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 12 ◽  
Author(s):  
Angelos P. Markopoulos ◽  
Emmanouil-Lazaros Papazoglou ◽  
Panagiotis Karmiris-Obratański
Keyword(s):  
Aluminum Alloy ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
White Layer ◽  
Machining Parameters ◽  
Machining Processes ◽  
Machining Conditions ◽  
Pulse On Time ◽  
Machined Surfaces

Although electrical discharge machining (EDM) is one of the first established non-conventional machining processes, it still finds many applications in the modern industry, due to its capability of machining any electrical conductive material in complex geometries with high dimensional accuracy. The current study presents an experimental investigation of ED machining aluminum alloy Al5052. A full-scale experimental work was carried out, with the pulse current and pulse-on time being the varying machining parameters. The polishing and etching of the perpendicular plane of the machined surfaces was followed by observations and measurements in optical microscope. The material removal rate (MRR), the surface roughness (SR), the average white layer thickness (AWLT), and the heat affected zone (HAZ) micro-hardness were calculated. Through znalysis of variance (ANOVA), conclusions were drawn about the influence of machining conditions on the EDM performances. Finally, semi empirical correlations of MRR and AWLT with the machining parameters were calculated and proposed.

scholarly journals Analysis, predictive modelling and multi-response optimization in electrical discharge machining of Al-22%SiC metal matrix composite for minimization of surface roughness and hole overcut

2020 ◽  
Vol 7 ◽  
pp. 20 ◽  
Author(s):  
Subhashree Naik ◽  
Sudhansu Ranjan Das ◽  
Debabrata Dhupal
Keyword(s):  
Surface Roughness ◽  
Metal Matrix Composite ◽  
Matrix Composite ◽  
Discharge Current ◽  
Metal Matrix ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Machining Parameters ◽  
Response Optimization ◽  
Pulse On Time

Due to the widespread engineering applications of metal matrix composites especially in automotive, aerospace, military, and electricity industries; the achievement of desired shape and contour of the machined end product with intricate geometry and dimensions that are very challenging task. This experimental investigation deals with electrical discharge machining of newly engineered metal matrix composite of aluminum reinforced with 22 wt.% of silicon carbide particles (Al-22%SiC MMC) using a brass electrode to analyze the machined part quality concerning surface roughness and overcut. Forty-six sets of experimental trials are conducted by considering five machining parameters (discharge current, gap voltage, pulse-on-time, pulse-off-time and flushing pressure) based on Box-Behnken's design of experiments (BBDOEs). This article demonstrates the methodology for predictive modeling and multi-response optimization of machining accuracy and surface quality to enhance the hole quality in Al-SiC based MMC, employing response surface methodology (RSM) and desirability function approach (DFA). Finally, a novel approach has been proposed for economic analysis which estimated the total machining cost per part of rupees 211.08 during EDM of Al-SiC MMC under optimum machining conditions. Thereafter, under the influence of discharge current several observations are performed on machined surface morphology and hole characteristics by scanning electron microscope to establish the process. The result shows that discharge current has the significant contribution (38.16% for Ra, 37.12% in case of OC) in degradation of surface finish as well as the dimensional deviation of hole diameter, especially overcut. The machining data generated for the Al-SiC MMC will be useful for the industry.

scholarly journals Parametric optimization of wire cut electrical discharge machining

2014 ◽  
Vol 3 (2) ◽  
pp. 212
Author(s):  
M. Durairaj ◽  
A.K.S. Ansari ◽  
M. H. Gauthamkumar
Keyword(s):  
Surface Roughness ◽  
Orthogonal Array ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Fluid Pressure ◽  
Performance Criteria ◽  
Dielectric Fluid ◽  
Machining Parameters ◽  
Pulse On Time ◽  
Pulse Off Time

Wire Electrical Discharge Machining is a manufacturing process whereby a desired shape is obtained using electrical discharges (or) by repetitive spark cycle. Precision and intricate machining are the strengths. Machining parameters tables provided by the machine tool manufacturers often do not meet the operator requirements. Selection of optimum machining and machining parameters combinations is needed for obtaining higher cutting efficiency and accuracy. In this present study, machining is done using Wire-Cut EDM and optimization of surface roughness is done using Taguchis design of experiments. Experimentation was planned as per Taguchis L16 orthogonal array. Each experiment has been performed under different cutting conditions of gap voltage, pulse ON time, and pulse OFF time and Wire feed. Dielectric fluid pressure, wire speed, wire tension, resistance and cutting length are taken as fixed parameters. Inconel 800 was selected as a work material to conduct the experiments. From experimental results, the surface roughness was determined for each machining performance criteria. Signal to noise ratio was applied to measure the performance characteristics deviating from the actual value. Finally, experimental confirmation was carried out to identify the effectiveness of this proposed method. Keywords: Optimization; Taguchis L-16 Orthogonal Array; Surface Roughness; S/N Ratio.

Effects of Electrical Discharge Energy on Machining Performance of Sintered NdFeB Magnet

2009 ◽  
Vol 620-622 ◽  
pp. 711-714 ◽  
Author(s):  
Li Li ◽  
Guang Ming Yuan ◽  
Zong Wei Niu ◽  
Rong Guo Hou
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Machining Parameters ◽  
Discharge Energy ◽  
Machining Performance ◽  
Ndfeb Magnet ◽  
Machined Surface ◽  
Micro Cracks ◽  
Ndfeb Permanent Magnet

Sintered NdFeB permanent magnet is widely used in many areas because of its excellent magnet property. In this study, the machining parameters of electrical discharge machining (EDM) are varied to study the effects of electrical discharge energy on material removal rate and surface roughness of NdFeB magnet. Moreover, the micro-cracks on the machined surface induced by EDM are also examined. The experimental results reveal that the MRR increases with the electrical discharge energy. The number of surface cracks on the machined surface increases with the enhancement of discharge energy Thus, using EDM process to machine sintered NdFeB magnet depends on setting the machining parameters to prevent surface crack.

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