How is the spark produced in Electric Discharge Machining ?
A typical circuit used for supplying the power to an EDM machine is named as the relaxation circuit. The circuit consists of a DC power source, which charges the capacitor ‘C’ across a resistance ‘Rc’. Initially when the capacitor is in the uncharged condition, when the power supply is on with a voltage of Vo, a heavy current, ic, will flow in the circuit as shown to charge the capacitor.The relaxation circuit as explained above was used in the early EDM machines. They are limited to the low material removal rates for fine finish, which limits its application. This can be explained from the fact that the time spent on charging the capacitor is quite large during which time, no machining can actually take place. Thus the material removal rates are low.
How to Calculate Time Constant from Charging Current?
Time Constant from Charging Current calculator uses Time Constant for EDM = -Time Elapsed for EDM/ln((Charging Current at any Time for EDM*Resistance of the Charging Circuit for EDM)/Voltage of Power Supply for EDM) to calculate the Time Constant for EDM, The Time constant from charging current formula is defined as the product of resistance of charging circuit to the capacitance of circuit. Time Constant for EDM is denoted by 𝜏cc symbol.
How to calculate Time Constant from Charging Current using this online calculator? To use this online calculator for Time Constant from Charging Current, enter Time Elapsed for EDM (tcc), Charging Current at any Time for EDM (ic), Resistance of the Charging Circuit for EDM (Rcc) & Voltage of Power Supply for EDM (Vcc) and hit the calculate button. Here is how the Time Constant from Charging Current calculation can be explained with given input values -> -48.705157 = -8.88/ln((6.1*0.18)/1.2).