本研究主要是利用微細電極前端以放電加工法形成一微球頭，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一微球頭，如此球頭部與電極根部形成直徑差，再以電化學加工法進行尺寸精修以達所需規格，期使獲得高精度之微型球狀探針電極，並藉由球狀探針電極達成高精度微孔電化學鑽孔加工加工目標。 由實驗結果可知電化學加工對放電修整後之電極表面具有拋光效果。放電修整完的電極表面粗糙度Ra值為0.304μm而採用電壓16V、加工時間0.5s、電解液濃度2 wt％加工參數進行電化學精修後Ra值降低至0.093μm。而對球形電極的表面具有精修效果，且電化學加工後球狀電極外形較為圓滑及可以控制球狀電極的直徑大小。在電化學鑽孔加工中，球狀電極比傳統圓柱電極有較小的環帶寬度及高精度的微孔直徑的之加工效果。With the development of micro machining or measurement technology, the demand for micro-spherical tools or probes such as using for micro-hole machining, coordinate measuring machine (CMM) and chip test has been rapidly increasing. Electrochemical micro machining (ECMM) is one of nonconventional micromachining processes; its material removal is an anode electrochemical dissolution process. The anodic electrochemical dissolution occurs when a voltage is applied between anode and cathode placed in electrolyte. This paper demonstrates a finishing process using ECMM (ECMF) to build an accurate and smooth micro-spherical tungsten electrode. A micro tungsten electrode is made by several processes including wire electro-discharge grinding (WEDG), electric discharge machining (EDM) spherical forming, and ECMF. The influence of ECMF parameters on the EDMed surface and tool diameter is presented. The experimental result shows a smooth micro-spherical tungsten electrode can be successfully finished and brightened with suitable ECMF parameters that are a voltage of 16 V, electrolyte concentration of 2 wt% and machining time of 0.5 second. When using this method, not only the micro tungsten electrode has a smooth surface and but also its diameter can be fine-tuned to get the high accuracy via the machining time control. Finally, the electrode is tested to drill a micro hole to compare with the machining performance by using conventional cylindrical electrode.
