Surface quality improvement of EDMed Ti–6Al–4V alloy using plasma etching and TiN coating

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• 作者：Hsin-Yun Hsu ; Chih-Chung Hu
• 关键词：Surface quality ; EDM ; Grey ; Taguchi method ; Shewhart control charts ; Plasma etching treatment ; TiN coating
• 刊名：The International Journal of Advanced Manufacturing Technology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：88
• 期：1-4
• 页码：67-74
• 全文大小：
• 刊物类别：Engineering
• 刊物主题：Industrial and Production Engineering; Media Management; Mechanical Engineering; Computer-Aided Engineering (CAD, CAE) and Design;
• 出版者：Springer London
• ISSN：1433-3015
• 卷排序：88

文摘

This paper seeks to improve the surface quality of electrical discharge machining (EDM) Ti–6Al–4V using plasma etching treatment and TiN coating. The EDM parameter setting is optimized firstly based on grey-Taguchi method. Four EDM parameters, including current (A), voltage (V), pulse duration (μs), and duty factor (%), are selected for multiple performance of lower electrode wear rate (EWR), higher material removal rate (MRR), and better surface roughness (SR). An orthogonal array, signal-to-noise (S/N) ratios, and analysis of variance (ANOVA) are used to analyze the effects of these EDM parameters. Normality tests show that all the distributions fit normality assumption with p = 0.276, 0.688, and 0.663, respectively. The EDM process is stable over time monitored by Shewhart control charts. It is observed that there is an EDM damaged layer on the surface consisting of debris, microcracks, molten drops, and solidified metals by scanning electron microscopy. The plasma etching and TiN coating are employed to improve surface quality of the EDMed Ti–6Al–4V alloys. The results demonstrate that using the oxygen plasma etching treatment, the damaged phenomena are decreased, and the mean SR value is reduced from Ra = 2.91 to Ra = 2.50 μm. In addition, when the plasma-treated alloy is coated with Ti buffer/TiN coating by physical vapor deposition, the surface morphology exhibits less defects and a better surface finish. The mean SR values are further reduced from Ra = 2.50 μm to Ra = 1.48 μm (for 740 nm TiN film) and Ra = 0.61 μm (for 1450 nm TiN film), respectively.