| Summary: | 博士 === 國立中央大學 === 機械工程研究所 === 88 === Micro Electro Mechanical System (MEMS) was acknowledged as the most valuable and foresighted research field in the last decades. More and more decisive mechanical elements were manufactured through this machining process such as micropump, microengine, microrobot, and micromechanical elements. To further inspect the MEMS machining elements, most of the well-known products were machined by either the micro-EDM or the superfine-wire as the adapted tool. However, the expansive and fragile nature of those machining tools was always limited to have any further applications. In contrast, with well designed modification on the conventional tools, those could also create the ability of having micro machining. A computerized horizontal four axes platform coupled with a precise rotational disc electrode was applied to explore the conventional technique in micro machining in this study. This technique helped in upgrading the conventional EDM to have the micro machining ability and widened the applications of EDM as well.
The horizontal micro-EDM applied in micro hole could increase the material removal rate in this study, yet, the process might also deform the machining hole toward ellipse. However, either the deformation of the machining hole or the slit expansion rate can be effectively suppressed by compiling with an optimized electrode voltage during machining. To apply the rotational disc electrode in micro slitting process could not only increase material removal rate but also help in suppressing the electrode wear rate uniformly along the disc electrode edge.
To add powder into kerosene in micro slitting process could increase the electrode gap. The drifted powder around kerosene could help in creating bridge effect which dispread the discharging energy and create several discharging scar within one pulse. This modified process could minimize the size of debris, accelerate the material removal rate and modify the surface roughness of the workpiece. However, the powder added into the kerosene might cause interfered carbon elements to attach onto the surface of electrode which increase the expansion rate of electrode and the slit expansion as well. To use pure water as working fluid in continuous cutting process could acquire a higher and steadier material removal rate. In contrast, the material removal rate was higher and degraded gradually while applying the kerosene as working fluid due to the attachment of carbon elements on the electrode. The burr around the edge of working piece could easily be observed while applying the pure water as working fluid in micro slitting process of titanium alloy, yet, the expansion rate of the slit was also larger compared to that of applying the kerosene. To add carbide silicon powder into pure water might increase the material removal rate, modify the surface roughness and suppress the burr along the edge of working piece, however, the added powder might increase the slit expansion rate and exhausting of electrode as well.
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