許多研究顯示，放電加工中添加鋁粉可以產生放電分散的效果，得到較佳的表面粗糙度，雖然鋁粉可以均勻分佈在放電加工液中，因鋁粉粒徑小而產生靜電力，導致鋁粉粉末容易聚集且不易分散於加工液。有鑑於此，本論文之研究目的主要是在探討放電加工液中添加鋁(Al)粉與界面活性劑(surfactant)對改善工具鋼放電加工面的效果，希望能藉由界面活性劑的分散效果，將鋁粉更為均勻地分散於放電加工液中，以達到最佳的表面品質，甚至能夠達到最理想的鏡面效果。 經由田口實驗設計分析顯示，放電加工液中添加鋁粉重量濃度為0.1g/L及界面活性劑重量濃度為0.25g/L，可以達到最佳的分散效果，藉由界面活性劑中的界面活性分子確實能將鋁粉更為均勻地分散於放電加工液中而改善加工特性。當使用正極性加工、電流0.3A、脈衝時間1.5μs、開路電壓140V、極間電壓90V及界面活性劑重量濃度為0.25g/L時，可以得到最佳的表面粗糙度(Ra 0.172μm)。並針對極性、電流、脈衝時間等不同放電參數來進行探討，並經由驗證放電加工液中添加鋁粉與界面活性劑之後，發現純放電液放電後的工件表面的表面粗糙度(Ra)為0.434μm，放電液中添加鋁粉及分散劑的放電表面粗糙度(Ra)可達0.172μm，改善率高達60%。 A lot of research have been exhibited, it can be seen that added Al powder in working fluid will reduce the isolation by its conductive powder and increase the gap distance between the electrode and workpiece to stabilize the process and generate discharging dispersion to improve surface roughness. Smaller size particle will have bring static electricity force and result in powder congregated. In this paper, some results on surface machining by EDM are treated in which several kinds of working fluid. The major research of this study investigates the effect on EDM characteristics by adding aluminum powder and surfactant into working fluid. Hoping to aluminum powder could disperse well mixed and pellet by pellet rely on scatter capability of surfactant is which obtained good quality surface and roughness by EDM. From the Taguchi method and experiment results, it can be seen that the surfactant could separate Al powder in the working fluid. Therefore, the parameters of polarity, peak current, and pulse duration discussed that added Al powder and surfactant in working fluid will reduce the surface roughness more than only added Al powder in working fluid. In this study, the parameters are positive polarity、peak current 0.3A、pulse duration 1.5μm in the working fluid of Al powder concentration 0.1g/L and surfactant concentration 0.25g/L. Surface roughness could achieve Ra 0.172μm. The surfactant in working fluid of Al powder is able to improve still more surface roughness.
