本研究主要是利用微細電極前端以放電加工法形成微球頭，於放電時瞬間熱能使電極前端產生熔融，因表面張力而收縮形成微球頭，經放電成球後其表面產生波浪狀紋路的再鑄層，而再鑄層表面散佈微細裂痕及氣孔等缺陷，致使球狀電極表面品質不佳。其球狀電極前端呈現橢圓狀。再分別利用球型圓柱狀修整槽與球型薄片狀修整槽進行微電化學加工，精修尺寸及球型修整以達所需規格，獲得高精度之微型球狀電極。 由實驗結果可知微電化學加工對放電成球後之球狀外形具有修整效果。球型薄片狀修整槽進行外形修整其效果不及球型圓柱狀修整槽。放電修整完的電極外形平均誤差達3.26%。利用球型圓柱狀修整槽進行全面性電化學加工，可得到較佳的修整效果其平均誤差值降為0.25%。而應用球型圓柱狀修整槽進行微電化學加工，當加工電壓12v、加工時間:3s、球型模穴:1mm、電極轉速:500rpm、可達到最佳平均誤差值為0.25%。 Electrical Discharge Machining (EDM) process could be used to form a micro spherical electrode tip. During EDM process, the non-uniform elliptical formation was made by multiple discharges, high heat energy melting and surface tension. At the same time, the material surface defects as micro-cracks, porosity and recast layer will affect the electrode quality. In this research, semi-spherical cavity and flake cathodes were applied respectively to trim elliptical shape to form the high precise microsphere electrode in micro electrochemical machining (?ECM) process. Experiment results show ?ECM could be successfully used to finish the elliptical shape. The semi-spherical cavity cathode is better than flake. After spherical EDM forming, average spherical shape error rate was 3.26 %. Using semi-spherical cavity cathode, the average spherical shape error rate was reduced to 0.25 %. The suitable parameters obtained for finishing spherical electrode are voltage of 12 V, machining time of 3 seconds, semi-spherical cavity cathode diameter of 1 mm and electrode rotation speed of 500 rpm.
