| dc.description.abstract | Due to their high hardness, high strength, favorable wear resistance, and brittleness, ceramics are difficult to process by using conventional cutting methods. In electrical discharge machining (EDM), the mechanical properties of the material being machined do not affect the machining. This experiment was conducted to investigate the effect of adding aluminum powder to a composite dielectric fluid used in the ultrasonic vibration assisted EDM of zirconia ceramic. The effects of processing parameters ultrasonic power level, high voltage current, pulse duration, and low voltage current on the results of EDM for zirconia ceramic workpieces were investigated. The quality characteristics of the machining included the machining time, machining depth, kerf width, electrode wear quantity, and surface roughness.
The machining depth was measured using an optical measuring instrument, whereas the surface roughness and kerf width were measured using laser scanning confocal microscopy. The surface morphology after machining was observed using a scanning electron microscope, and the elements in the processing zone were analyzed using an energy-dispersive X-ray spectrometer.
The experimental results revealed that when ultrasonic power assistance was applied, the pumping effect facilitated the infiltration of the machining zone by the aluminum powder-enhanced dielectric fluid and helped discharge debris. This led to less-concentrated discharge during EDM, resulting in more favorable surface roughness of the machined workpieces. Additionally, the magnitudes of the high voltage current and low voltage current significantly affected the machining time, machining depth, and kerf width, and the pulse duration strongly affected the surface roughness.
The optimal combination of processing parameters was determined to be an ultrasonic power level of 2, high voltage current of 2.4 A, pulse duration of 50 μs, and low voltage current of 1 A. This combination resulted in a post machining surface roughness of 1.23 μmRa. The surface roughness achieved without any ultrasonic power stages was 1.41 μmRa; thus, the assistance achieved a 12.7% reduction in roughness. The results of this experiment can serve as a reference for the subsequent processing of nonconductive materials. | en_US |