本論文研究目的主要探討微細放電加工參數對加工表層特性之影響。利用放電研磨法(EDG)及線放電加工法(WEDG)將碳化鎢電極加工至電極尺寸150μm，針對試件SKD11進行1mm深度的微孔加工。加工完成後，分別量測與觀察擴孔量、電極消耗、實際加工深度、電極消耗長度與試件加工深度之消耗比、白層厚度以及表面裂紋與形貌，所得結果再與加工參數進行討論。
本研究主要分為兩個部分，首先選取放電電流與放電持續時間為放電製程參數，進行全因素實驗以探究兩種放電加工參數與放電加工後表層特性之關係。第二部分則利用第一階段的全因素實驗求得之適用放電加工參數，探討Duty Factor對放電表層特性的影響。
研究結果顯示，若放電電流選用0.1A-0.3A且放電持續時間採用15μs以下，除了加工時間可控制在15分鐘以內，擴孔形貌可保持完整，實際加工深度穩定且加工效率較佳之外，白層厚度可維持在2.5μm~4μm範圍內且單一參數的白層表面起伏程度降低，表面裂紋數量少且裂紋形態單一，其幾乎為穿孔裂紋。
在Duty Factor方面，隨著衝擊因子提高，不論擴孔量、實際加工深度、白層平均厚度以及表面裂紋數量等都有微幅的提升，且孔底形貌逐漸形成尖錐狀。此外，當放電持續時間設定在2μs及6μs時，Duty Factor增加可降低加工時間進而提升加工速率，但是當放電持續時間縮短至0.5μs時，Duty Factor增加反而延長加工時間，導致加工效率降低。

This study evaluates the effects of working parameters on surface integrity of micro-holes drilled by the Micro-EDM process. Micro electrodes with 150μm in diameter were manufactured by EDG and WEDG, and used to drill blind holes with depth of 1 mm on tool steel SKD11. Effects of hole enlargement, electrode wear, hole machining depth, wear ratio, thickness of white layer, and surface crack were analyzed.
There are two main concerns in this study. First , pulse current and pulse-on duration were selected as the working parameters for full factorial experiment to get the relationship between these two parameters and surface integrity. Second, using these parameters acquired from part one to study the effects of Duty Factor on surface integrity.
Experimental results revealed that the optimum surface integrity was obtained when pulse current was selected in the range from 0.1 A to 0.3A and pulse-on duration was below 15μs, where the white layer thickness maintained at 2.5μm-4.0μm , minimum surface roughness , less surface crack and most of them were pore cracks.
Moreover, hole enlargement, hole machining depth, and mean thickness of white layer were all increased with increasing the Duty Factor, and blind holes tend to be cone-shaped. When pulse-on duration was 2μs or 6μs, increasing the Duty Factor can also increase the material removal rate. However, when the pulse-on duration was down to 0.5μs, increasing the Duty Factor will increase the working time so as to lower the material removal rate.

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