Electro-thermal modelling of anode and cathode in micro-EDM

Abstract

Micro-electrical discharge machining is an evolution of conventional EDM used for fabricating three-dimensional complex micro-components and microstructure with high precision capabilities. However, due to the stochastic nature of the process, it has not been fully understood. This paper proposes an analytical model based on electro-thermal theory to estimate the geometrical dimensions of micro-crater. The model incorporates voltage, current and pulse-on-time during material removal to predict the temperature distribution on the workpiece as a result of single discharges in micro-EDM. It is assumed that the entire superheated area is ejected from the workpiece surface while only a small fraction of the molten area is expelled. For verification purposes, single discharge experiments using RC pulse generator are performed with pure tungsten as the electrode and AISI 4140 alloy steel as the workpiece. For the pulse-on-time range up to 1000 ns, the experimental and theoretical results are found to be in close agreement with average volume approximation errors of 2.7% and 6.6% for the anode and cathode, respectively.

Mathematical and numerical modeling of the effect of input-parameters on the flushing efficiency of plasma channel in EDM process

“…In other study, Hashimoto et al [10] reported a distribution of 34% and 48% discharge energy into the cathode and anode, respectively. Having modeled of heat distribution in anode and cathode in micro-EDM, Yeo et al [11] proposed a fraction of 14% and 39% of discharge energy to the anode and cathode, respectively.…”

Modeling the Effects of Electrical and Non-Electrical Parameters on the Material Removal and Surface Integrity in Case of μEDM of a Non-Conductive Ceramic Material using a Combined Fuzzy-AOM Approach

“…The discharge voltage Vd [11] at the onset of breakdown is: (2) where, α is a correction factor associated with dielectric strength, S is a constant based on electric field, n is a constant depending on the polarity, d is the inter-electrode gap length, A is the area of the tool electrode exposed to electric field and t is the time of breakdown. Furthermore, because of movement of electrons, the kinetic energy is converted into heat energy developed at the anode surface [12]. The heat flux q (r) at a radial coordinate r is given by:…”

Multifilament carbon fibre tool electrodes in micro EDM—evaluation of process performance based on influence of input parameters

“…When selecting the proper material for electrodes, one has to take into account not only conductivity, which is essential for electrodes in EDM, but also other features, like machinability and availability of the material along with thermal properties, mainly because of the thermal character of the process [24,25].…”