Experimental investigation of drillability of micro holes using electro discharge machining

In this study, experiments were conducted in order to obtain micro-holes using electrical discharge machining (EDM) method at different processing parameters (discharge current, pulse duration, electrode rotational speed, dielectric spray pressure). Within this scope, a pressure head that rotate the electrode tool and simultanously eject the dielectric fluid within the desired pressure is mounted on EDM. In experiments, hadfield steel which is difficult to cut with conventional manufacturing processes due to deformation hardening and AISI 1040 steel that is quite widely used for the manufacturing industry, and is easy to cut with conventional manufacturing processes were machined with the same process parameters using tube-type brass electrode tools and the results were compared. After experiments, discharge current (I) was determined as the most effective processing parameter and the workpiece removal rate (MRR), electrode wear rate (EWR), relative wear (RW), surface roughness (Ra), the dimensional error (% DE), and the average radial overcut (ARO) values increased with the increase of the discharge current. MRR, ARO, DE and Ra values increased with increasing duration of the pulse. With the increase in dielectric injection pressure the continuity of drilling ensured, MRR increased, DE and Ra values decreased. With the increase in rotational speed of the tool electrode, holes were drilled more easily, MRR increased, and the reduction of Ra was obtained. Evaluation of data obtained after experiments, it was determined that with this method, for all metals provided that it has the electrically conductive structure, smooth and deep holes can be drilled.