Nonconventional Technologies Review - no. 4 / 2007 103 ELECTRICAL CHARGE AS MEASURE FOR THE REMOVED METAL MASS AT THE ELECTRICAL DISCHARGE MACHINING Pavel TOPALĂ 1 ABSTRACT. The paper presents some authors considerations concerning the drop voltage in the work gap during the electrical discharge machining. The author considers that the mass quantity of material removed by a single electrical discharge depends on the charge quantity which passes in the work gap. KEYWORDS: electrical discharge machining, discharge energy, work gap, voltage drop 1. INTRODUCTION The development of the modenr science and technique supposes the introducing new materials which need adequate machining technologies. A solution to solve the problem of material machining is the applying generally the non-conventional technologies and particularly the electrical discharge machining. In the case of the electrical discharge machining processes, at the dimensional machining [1, 2] or at the generatin the deposition layers [3], the melting and removal of the material existing on the electrodes surfaces occur and the getting of some cavities having spherical calottes. The researchers working in this field tend to establish the relation between the quantity of the melted and removed material as a function of different parameters: pulses frequency, the gap size, then properties of the electrodes materials, the average intensity of electric current in pulse, the energy of the electrical discharges etc. Usually, the absolute majority nof the researchers appreciate that the main parameter significantly influencing the erosive processes is the energetic factor of the electrical discharges in pulse. Thus, some researchers proposed to be used the relations: kW d c = (1) kW h c = (2) 2 2 CU k = ∆γ (3) kW = ∆γ (4) In which d c is the diameter of the cavity obtained as the result of the single electrical discharge, h c – the depth of the cavity, ∆ y – the quantity of removed or deposited material, k – proportional coefficint depending on the electrodes materials properties and on the working conditions., C – the capacity of the capacitors included in the pulse generator circuit, U – the voltage for charging the capacitors, W – the energy of the electrical discharges in pulse. The relations (1), (2), (3) and (4) are relatively simple, but simoultanously they are not sufficient clare and as consequence, the results obtained by different researchers could not be adequately interpreted. If we analyze the relation (3), we will see that the energy accumulated in the capacitors battery can not be used as a technological index, because all the discharges circuits include active, capacitive,and inductive resistances and, respectively, during the pulse electrical discharge process, a part of the energy accumulated on the capacitors battery is dissipated by it (table 1), and the energy lost is a function of many factors (the correloation between the inductance and capacity, the modality to introduce the inductance and the