Electro-chemical Micro Drilling Using Micro-spherical Electrode

With the development of Micro-Electro-Mechanical System (MEMS), parts and components become more and more miniaturized size. Corresponding, high quality micro hole processing is caused more and more attention. Electro-chemical machining (ECM) has many advantages of good surface roughness and no heat affected layer on the machined surface. And because material is dissolved at the units of an atom, it could produce nano-precision parts in theory. Therefore, micro-ECM shows great development potential and prospect in micro-machining, causing more and more concern of researchers.However, ECM was not usually used for micro drilling because of the taper generation. In this thesis, the straight deep holes with a few micrometers diameter is drilled by using micro-spherical electrode and regulating the machining conditions. Research works were listed as follows:(1) A new method of fabricating micro-spherical electrode has been presented. Micro-spherical electrode could be fabricated by micro-ECM with one-pulse-electro-discharge (OPEG) technology. The key factors, such as the working polarity, the working voltage, the electric discharge duration, the peak current and so on, which impact the fabrication of the micro-spherical electrode was studied. High quality micro-spherical electrode were fabricated successfully.(2) Electro-chemical micro drilling using micro-spherical electrode and ultra short pulses is studied in this thesis. To obtain a straight deep micro hole, the effects of the voltage, the pulse on-time, the pulse period, feed rate on the localization distance were investigated. High quality straight micro holes with 42μm diameter in 70μm thickness nickel foil were drilled using micro-spherical electrode with 30μm diameter.