| dc.description.abstract | The study used helical tool for electrical discharge micro hole drilling (EDMD) process on Fe-based metallic glass and polishing the inner surface of the micro hole by making composite by electrophoretic deposited tool. The experiment can be divided into three parts. In the first part, EDMD was performed by using helical tool. The influence of processing parameter including pulse on time, gap voltage, duty factor and spindle rotational speed on micro hole machining accuracy, machining time and electrode wear length were investigated. In the second part, the influence of parameters such as deposition time and voltage, on the shape of the deposition and diameter of tool. In the third part, the electrophoretic deposited tool was used to polish the inner surface of the electrical discharged micro hole. SEM and LSCM were used to observe and measure the shape of micro hole inner walls and surface roughness. In addition, XRD was used to identify the crystallization phase.
In terms of processing parameters, there is a significant increased by 48% in machining time as the pulse on time was increased from 5 µs to 20 µs, and the electrode wear length was increased as well. Also, when the pulse on time was longer, the larger craters were formed. As the gap voltage were increased from 30 V to 50 V, the inlet diameter, outlet diameter and machining time were increased. The tool wear length was the longest at the gap voltage of 30 V. The processing efficiency and the worst micro hole accuracy were obtained at the duty factor of 20%. A significant machining time was decreased by 74% as the pulse on time increased from 20% to 40%. The best micro hole accuracy, tool wear length and the inner surface, were obtained at the spindle rotation speed of 1150 rpm. The composite tool was made by electrophoretic deposition. The surface roughness of the workpiece can be reduced from 0.427 µm to 0.018 µm after the inner surface polishing. The inner surface was polished up to mirror surface. The XRD pattern shows that the crystalline phase of Si was generated after processing. | en_US |