In this study, heated silicon oil with added carbon and starch powders was used as dielectric liquid, instead of common hydro-carbon based dielectrics, to obtain better hole surface quality with rotating brass tube electrode in electric discharge machining (EDM). The electro-rheometer tests were conducted to find out the suitable temperature and powder concentration values of the electro-rheological (ER) dielectric under the electric field. Higher workpiece material removal rates (MRR) was obtained in carbon powder added dielectrics than the starch powder added ones for rotating and non-rotating electrodes. The optical microscope observations of the machined hole surfaces indicated that the carbon powder added dielectrics reduced the diameter and depth of the discharge craters, thereby resulting in uniformly distributed and round top peaked surface topography. The starch powder addition to the carbon mixed dielectric further improved the surface quality for both rotating and non-rotating electrodes cases at 30˚C and 75˚C dielectric temperatures.

No abstract

No abstract

No abstract

No abstract

No abstract

The most crucial cost element of Electric Discharge Machining (EDM) is the production of tool electrode (shortly electrode). Copper, its alloys, and graphite are the most commonly used electrode materials. Selecting the proper electrode material with low production and material cost, high workpiece material removal rate (MRR) and low tool electrode wear rate (TWR) is key to reducing machining costs with EDM. In this study, the EDM performance of CuBe tool electrodes in the machining of Ti6Al4V alloy was experimentally investigated in comparison to electrolytic Cu (E-Cu) electrodes for different pulse time (ts) and discharge current (I) settings. An increase in MRR and a decrease in TWR and relative wear (RW=TWR/MRR) were observed in machining with CuBe electrodes. However, the high raw material cost of CuBe alloy is an essential drawback in widely using these electrodes in industrial applications. A new performance index formulation is introduced for EDM applications that factor in the production cost of the electrode and its life (i.e., RW). According to our results, the CuBe could be used advantageously as the electrode material at medium current settings. However, at low and high current settings, the low raw material cost of E-Cu makes it more favorable.

In this study, the machinability of B4C and TiB2 reinforced Al 2024 based composites produced by powder metallurgy was investigated with EDM (Electro Discharge Machining) method using two different copper electrodes. For this purpose, composite samples were produced at 6% TiB2+12% B4C reinforcement ratios. Then, scanning electron microscopy images were taken to examine the microstructure of the composite samples. Also EDAX analyzes were performed during SEM images. In EDM machinability experiments of the composite material two different electrodes; pure copper and beryllium copper were used. The experiments were carried out using three different current (I) and arc pulse on time ( ton) and two different arc pulse off time ( toff) parameters. As a result of EDM experiments, roughness measurements of the machined surfaces were made and SEM images of the machined surfaces were taken again. According to the experimental findings, material removal rate increased in machining with CuBe tool compared to machining made with pure Cu and CuBe tools showed higher wear tendency than Cu tool sunder the same machining conditions and roughness values in CuBe electrodes were lower than machining made with pure Cu. And the roughness values of CuBe are lower than the machinings with pure Cu.