| Summary: | 碩士 === 崑山科技大學 === 機械工程研究所 === 96 === Micro-hole electrical discharge machining（Micro-hole EDM）has advantageous characteristics of machining for micro-components and difficult cutting materials with high hardness and high strength. However, because the effect of rapidly heating and fast cooling during the period of machining, the defects, such as micro-cracks, gas holes…etc., was easy to be induced serious influences for machined surface quality.
In this study, the high yielding steel（HY-80） was employed to proceeding micro-hole electrical discharge machining and the material removal rate （MRR）,electrode removal ratio（ERR）, hole-enlargement（HE）, surface morphology were investigated. And the relationship between machining parameters and machining characteristics was studied.
Based on the results of experimental analysis, the pulse current and duration on time increase the MRR and HE will increase. The SEM was used to observe the change of surface topography for high yielding steel of inlet region, middle region, and outlet region after EDM. And when the pulse current was increased, the deeper and bigger EDM craters were found and the height of EDM crater was decreased. The duration on time was increased, the area of EDM crater was increased and the height of crater and pockmark were decreased. Observing the surface crack, we found the less of pulse current, the fewer of the crack. And the pulse current was increased, the number of crack was getting fewer.
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