| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 105 === This work is to evaluate the machining performance in multiple objectives when cutting of polycrystalline dick using wire electrode discharging method. The 2 μm polycrystalline with 8-15% cobalt having weak conductivity (1.8×10-4 (Ωm)-1) and necessitated a bespoke feature to couple with preferable parameter sets for discharging actions. In this experiment, the influences of open voltage (80-180 V), ignition intensity (0.4-0.9 A), pulse on-time (0.1-0.3 µs), pulse off-time (10-20 µs) on the material removal rate, surface roughness, surface asperity and edge radius was resolved with statistical methods (ANOVA) in an orthogonal array (Taguchi L18). The developed empirical model suggests the preferable parameter sets for the multi-objective optimization while equal weightings are given to each objective. The results suggest the high pulse on-time (0.3 µs) produce higher material removal rate (22.9 mg/min) and the lower pulse on-time (0.1 µs) produce lower surface roughness (Ra 1.42 µm) whilst the lower open voltage (80 V) leads to lower surface asperity (0.63µm) and small edge radius (32.6 µm) on the machined surface. When compared the experimental results to the modelling values, the least error for material removal rate, surface roughness and surface asperity are 10.3%、3.04%、26.09% respectively under the preferable parameters of open voltage (126 V), ignition intensity (0.9 A), pulse on-time (0.1 µs), and pulse off-time of (20 µs).
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