The influences of the mask wall angle on the current density distribution,shape of the evolving cavity and machining accuracy were investigated in electrochemical machining(ECM) by mask.A mathematical model was developed to predict the shape evolution during the ECM by mask.The current density distribution is sensitive to mask wall angle.The evolution of cavity is determined by the current density distribution of evolving workpiece surface.The maximum depth is away from the center of holes machined,which leads to the island appearing at the center of cavity for mask wall angles greater than or equal to 90°(β≥90°).The experimental system was established and the simulation results were experimentally verified.The results indicate that the simulation results of cavity shape are consistent with the actual ones.The experiments also show that the repetition accuracy of matrix-hole for β≥90° is higher than that for β<90°.A hole taper is diminished,and the machining accuracy is improved with the mask wall angle increasing.
A human face with complex 3D structure is machined with a modified fix-length compensation method in this paper.The fast development of MEMS (Micro Electromechanical Systems) has strongly enhanced the application of new harder work materials.As a low cost,flexible,good repeatable machining process with negligible process forces,micro-EDM milling is well suited for freeform metallic micro structures.A major problem in micro-EDM milling of complex 3D structure is the electrode wear.A new CAM system based on the UG software platform is developed in order to get good accuracy and higher efficiency.A correction coefficient is introduced and deduced for the modified fix-length compensation method.Using this method a human face with complex 3D stricter is machined successfully by micro-EDM milling.
