利用微細電極進行放電鑽孔是很經濟的微孔加工方式，但是放電時因為電極消耗的關係，造成微孔的精度不夠理想。為解決此問題，本實驗結合微放電與電泳沉積現象，並進行超音波振動研磨來獲得微孔精度的改善。 在預備實驗時，先針對電泳沉積找尋最佳條件，因為電泳沉積效應會讓磨粒有效的吸附在研磨工具電極上，增加超音波振動研磨的效果；經由實驗結果得知當沉積時間為6分鐘、溶液酸鹼值pH8、外加電場30V、SiC濃度15wt%、電極旋轉速率50rpm為電泳沉積最佳參數。之後將電極修整成所需的尺寸與形狀，並利用此電極對鈦合金工件進行微能量放電鑽孔。然後電泳沉積與超音波振動對微孔進行研磨拋光加工，以改善放電微孔的精度。 由實驗結果可知當超音波振幅為5μm、電極轉速為50rpm、使用階級差電極及缺口電極進行加工時，其真直度改善率可達56%，而孔內壁的表面粗糙度可達到Rz=0.449μm，另外使用階級差電極進行電泳沉積研磨，可得到最佳的真圓度。綜合上述實驗結論可知，此種複合加工方式確實提昇微孔的精度。 Drilling micro hole with micro-electric discharge machining (Micro-EDM) is an economic machining method. However, because of the electrode wearing, the precision of micro hole is not well enough. For solving this problem, we combined Micro-EDM, electrophoretic deposition (EPD) and ultrasonic vibration grinding to get high precision shaft with better inner surface. Before experiment, we searched the best parameters of EPD first. Because loose abrasive grains are attracted to grinding tool (electrode) and fixed on the tool surface by EPD, this phenomenon will increase the ultrasonic vibration grinding efficiency, and we found 6 min(deposition time), pH8, 30V(potential), SiC 15wt%(concentration of slurry), 50rpm(electrode rotation rate) are the best parameters. After the process above, we modified the electrode shape with WEDG and drilled the micro hole on titanium alloy by the electrode that had made. Then improved the precision of micro hole by combination of EPD and ultrasonic vibration grinding. As the result, when we set amplifier to be 5μm, electrode rotation rate to be 50rpm, and use stepped or breached electrode, the improvement of straightness will be up to 56%. And the inner surface roughness will be 0.449μm(Rz). Besides, using stepped electrode will get the best roundness. So this composite machining process was efficient method to improve the precision of micro holes.
