Toward synchronous hybrid micro-EDM grinding of micro-holes using helical taper tools formed by Ni-Co/diamond Co-deposition

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• 作者：Albert Wen-Jeng Hsue ; ^{albert.hsue@kuas.edu.tw" class="auth_mail" title="E-mail the corresponding author} ; ^{wjhsue@me.com" class="auth_mail" title="E-mail the corresponding author} ; Yu-Fu Chang
• 关键词：micro-EDM ; Grinding ; Synchronous hybrid processes ; Nickel-Cobalt Co-deposition ; Helical tool ; Taper-tip
• 刊名：Journal of Materials Processing Technology
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：234
• 期：Complete
• 页码：368-382
• 全文大小：7357 K

文摘

In micro-machining, a secondary grinding process following the micro Electrical Discharge Machining (micro-EDM) is generally required for molding and manufacturing applications owing to the presence of recast layer and micro-craters. This study proposes a one-stop scheme toward synchronous micro-EDM grinding process (micro-EDMG) for the precision drilling and precision polishing. To implement this hybrid synchronized process, a micro-tool of tungsten carbide is dressed by the wire electrical discharge grinding system, and it is co-deposited with fine diamond abrasives in a nickel-cobalt electroplating bath. The set-up involves a single machine tool, which is retrofitted from micro-EDM machine with low- and high-speed spindles, to achieve micro-EDMG with micro-tools under 0.3 mm diameter. This approach is simple and supports intuitive processing as an efficient one-stop solution, eliminating the difficulty of the highly repetitive precise positioning of grinding tools. A novel helical micro-tool has a carefully determined depth-diameter ratio and a short taper-tip to improve the EDM penetration and drilling efficiency. The presence of cobalt ions in the nickel deposition bath is aimed at improving the wearing resistance of the tools. Typical surface features of the machined region were examined after such a micro-EDMG process. Finally, the best surface roughness obtained using the proposed strategy was Ra 0.107 μm and the diameter difference between the entrance and the exit of the micro-holes was 5 μm for an SUS 304 stainless steel plate with a depth of 300 μm. The through-hole taper errors ranged from 1.6% to 2.5% in three tests with such a single co-deposited tool.