Theoretical models of the electrical discharge machining process. I. A simple cathode erosion model

Abstract

A simple cathode erosion model for the electrical discharge machining (EDM) process is presented. This point heat-source model differs from previous conduction models in that it accepts power rather than temperature as the boundary condition at the plasma/cathode interface. Optimum pulse times are predicted to within an average of 16% over a two-decade range after the model is tuned to a single experimental point. A constant fraction of the total power supplied to the gap is transferred to the cathode over a wide range of currents. A universal, dimensionless model is then presented which identifies the key parameters of optimum pulse time factor (g) and erodibility (j) in terms of the thermophysical properties of the cathode material. Compton’s original energy balance for gas discharges is amended for EDM conditions. Here it is believed that the high density of the liquid dielectric causes plasmas of higher energy intensity and pressure than those for gas discharges. These differences of macroscopic dielectric properties affect the microscopic mechanisms for energy transfer at the cathode. In the very short time frames of EDM, our amended model uses the photoelectric effect rather than positive-ion bombardment as the dominant source of energy supplied to the cathode surface.

Aspects on the optimization of die-sinking EDM of tungsten carbide-cobalt

“…From investigations of DiBitonto et al (1989), Mukund et al (1989), Eubank et al (1993), König and Klocke (1997), Kunieda et al (2005), and many other researchers, the material removal in electrical discharge machining is associated with the erosive effect produced when spatially and discrete discharges occur between two electrical conductive materials. Sparks of short duration, ranging from 0.1 to 4000 µs, are generated in a liquid dielectric working gap separating the electrode and the workpiece (10-1000 µm).…”

An Influence of Parameters of Micro-electrical Discharge Machining on Wear of Tool Electrode

“…4. An increase in the number of charged particles increases the number of collisions, which further enhances the transfer of the proportion of heat energy to the cathode [34].…”

Electro-Spark Nanomachining Process Simulation

“…where, F is the percentage (18 %) of the total power which is transmitted into the work piece [11], V is the average of spark voltage (v), I is the average electric current of spark (A), R(t) is radius of heat source located on the workpiece surface (equal to the plasma channel radius) (m). Plasma channel radius of the spark nanomachining process depends on time and is computed via (7) [10].…”