Modeling of Vibration Assisted Micro Electrical Discharge Machining for Fabrication of Micro Holes in Inconel 718

Abstract

Owing to the increasing trend towards miniature and lightweight components for various applications, manufacturing industries are developing new technologies to meet the unique challenges posed by micro manufacturing. Fabrication of micro-sized components using micro-EDM is one of the significant steps towards miniaturization. The inherent characteristic of micro-EDM is the capability of machining of three-dimensional complex micro-components used in biomedical, optical, aerospace, automobile, and electronics industries. Due to the high accuracy of machined parts and lower machining cost, micro-EDM becomes a more promising method used for the machining of difficult-to-machine materials like Inconel 718. Despite several advantages, micro-EDM alone cannot satisfy the numerous prerequisites of the machine parts because of few disadvantages like low machining rate and high tool wear.

The characteristics of micro-EDM are influenced by several controllable process parameters, which make it difficult to locate the optimum parameters without understanding the mechanism of material removal rate. Therefore, there is a need to understand the fundamentals of process mechanism by developing a numerical model for micro-EDM process.

The aim of this research is to develop the FEM based thermal model for the micro-EDM process to understand the crater formation and material removal rate on the surface of the workpiece. Initially, the finite element analysis was carried out to obtain the crater geometry and temperature distribution on the workpiece surface due to single spark in the micro-EDM process. The developed model proposes to enable the understanding of temperature distribution and shape of the crater in the micro-EDM process without workpiece-vibration. Further, the thermal model for vibration-assisted micro-EDM has been developed to understand the crater morphology and material removal mechanism in micro-EDM with aid of workpiece vibration. A numerical simulation has also been carried out to simulate the flushing of the debris from the gap between the electrodes when there was no vibration and when a vibration was applied to the workpiece in the micro-EDM process.
In the second phase of this research, an experimental investigation has been carried out on micro-EDM operation in Inconel 718 to validate the simulation results without vibration of the workpiece. A parametric study has been carried out to analyze the effect of the process parameters on material removal rate, accuracy and surface quality of the fabricated micro-holes in Inconel 718.