Electrical discharge machining is an electro-thermal technique where the recast layer on a machined surface and the heat-affected zone (HAZ) immediately below the machined surface are prevalent. As a ...result, assessing the white layer (recast layer) in EDM is a critical task. In this research, a response-surface methodology-based comprehensive mathematical model was developed to predict the white-layer thickness (WLT) on electrical discharge machine-processed AISI A2 steel. Also, the effects of various process parameters on the WLT were presented, the optimum combination of process variables was assessed and the minimum WLT was achieved by combining low-peak current and pulse-on time with high pulse-off time.
Electrical discharge machining (EDM) is much preferred in modern precision-manufacturing industries owing to its ability to machine any metal regardless of its hardness. However, its constraint is ...that the selected metal should be an electrically conductive material. For the present investigation, an Inconel 718 alloy was selected for EDM, using a TiB2-Cu electrode made with powder metallurgy. Input factors, namely, the pulse current (Ip), pulse-on time (Ton) and gap voltage (Gv) were selected and their output responses were the surface roughness (SR) and material-removal rate (MRR). For the response surface, the Box Behnken technique was preferred when designing the experiments (DoE). An ANOVA test was performed to understand the influence of the selected input factors on the SR and MRR. The RSM integrated with a grey relational analysis (GRA) revealed that the optimal input parameters for better machining characteristics were: Ip = 10 A, Ton = 40 µs and Gv = 50 V. Besides, the results also showed that the pulse current more significantly influenced the output responses than the other parameters. Moreover, an increase in the gap voltage caused surface irregularities on the machined surface. Surface morphology of the machined surfaces was analysed through SEM and EDAX. Moreover, a certain amount of tool-material transfer was noted with the EDAX analysis.
Due to the creation of a significant temperature gradient, electrical discharge machining (EDM) causes localized, high thermal stress in a tiny heat-affected zone. This thermally developed stress ...leads to fatigue life and strength decrement, micro-cracks and probably catastrophic failure. On AISI A2 steel, a mathematical model based on finite-element analysis was constructed to estimate the temperature field and associated thermal stresses. In this present research work, the heat-flux distribution in a single spark during EDM is considered to be Gaussian distributed. The model first calculates the temperature distribution, and then uses this temperature field to determine the thermal stresses. It was observed that the stresses surpass the workpiece material’s yield strength near the center of the spark and this gradually weakens as the distance from the center increases.
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