Experimental Optimization of micro-electrical discharge drilling process from the perspective of inner surface enhancement measured by shear-force microscopy
Authors: Rashed C.A.A., Romoli L., Tantussi F., Fuso F., Bertoncini L., Fiaschi M., Allegrini M., Dini G.
Autors Affiliation: a Department of Civil and Industrial Engineering, University of Pisa, Pisa, Italy
b Department of Physics, University of Pisa, Pisa, Italy
c Continental Automotive Italy S.p.A., Italy
Abstract: The inner surface morphology of micro-drilled holes obtained by EDM was analyzed using Shear Force Microscopy (SHFM). Two drilling combinations were considered defining standard pulse energy (15μJ) adopted for automobile applications and low pulse energy (3.25μJ). Discharge current and pulse duration were used as input parameters to determine spark energy. The surface morphology was measured in three regions along the hole axis to characterize its evolution with the increase of the drilling depth. The obtained results confirmed that the primary surface texture was characterized by (i) maximum peak-to-valley distance and (ii) periodicity which were found to be sensitive to the variation of process parameters. Standard Rq was derived from the measured areas for both conditions identifying an average value of 380nm for standard and 240 nm for low energies. Moreover, considering the combination of two energy levels, it was demonstrated that switching to low energy pulses after drilling through with standard energy has the beneficial effect of reducing Rq of about 30% with a very restricted increase in process time.
Volume: 7 Pages from: 11 to: 19
KeyWords: Micro-EDM; Surface Roughness; Shear Force Microscopy