Modeling and Analysis of Machinability Evaluation in the Powder Mixed Electrical Discharge Machining of Cobalt-Bonded Tungsten Carbide

碳化鎢於粉末混合放電加工過程中加工性能之建模與分析

江可達(Ko-Ta Chiang)；張浮明(Fu-Ming Chang)；劉南明(Nun-Ming Liu)；周志忠(Chih-Chung Chou)

建模 ； 粉末混合放電加工 ； 加工性能 ； 反應曲面法 ； Modeling ； powder mixed electrical discharge machining ； machinability evaluation ； Response surface methodology

修平學報

31期（2015 / 10 / 01）

1 - 28

英文

對於粉末混合放電加工過程中，添加於介電液中的鋁粉末具有對於放電能量的分散與均化作用，使得單一輸入的放電脈衝呈現有放大其放電能量的效應。本文的研究目的是呈現一數學模組用於建模與分析其放電加工參數，包含有放電電流、脈衝時間、鋁粉的顆粒大小與濃度等，對於碳化鎢於粉末混合放電加工過程中加工性能如材料移除率、電極消耗率與表面粗糙度等的影響。實驗規劃上採用反應曲面法為基礎的中央組台法來進行實驗的研究。本文著重於數學模組的開發用於探討其放電加工參數對於加工性能的影響，所提的數學模組獲得證實可吻合與預測其加工性能並有95%可靠度接近其實驗值。結果顯示，添加於介電液中的鋁粉末具有同時提升其材料移除率、電極消耗率的數值。其表面粗糙度會隨著鋁粉的濃度增加而減少，卻隨著鋁粉的顆粒增大而增加。而放電電流、脈衝時間對於材料移除率、電極消耗率與表面粗糙度等的加工性能皆有統計上明顯的影響。

For the powder mixed electrical discharge machining (PM-EDM) process, the aluminum powder particle suspended in the dielectric fluid disperses and uniforms the discharging energy dispersion, and displays multiple discharging effects within a single input pulse. The objective of this paper was to present the mathematical models for modeling and analysis of the effects of processing parameters, including the discharge current, pulse on time, grain size and concentration of aluminum powder particle, on the machinability evaluation in terms of material removal rate (MRR), electrode wear ratio (EWR) and surface roughness (SR) in the PM-EDM process of cobalt-bonded tungsten carbide. An experimental plan of a central composite design (CCD) based on the response surface methodology (RSM) was employed to carry out the experimental study. This study highlighted the development of mathematical models for investigating the influences of processing parameters on the machinability evaluation, and the proposed mathematical models in this study had proven to fit and predict values of performance characteristics close to those readings recorded experimentally with a 95% confidence interval. Results show that the effect of aluminum powder particle added in the dielectric fluid promotes both the values of MRR and EWR, simultaneously. The value of SR decreases with an increase of powder concentration, and increases with an increase of grain size for various powder concentrations. The discharge current and the pulse on time have statistically significant on the values of MRR, EWR and SR.

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