Transitions of micro-EDM/SEDCM/micro-ECM milling in low-resistivity deionized water
Transitions of micro-EDM/SEDCM/micro-ECM milling in low-resistivity deionized water
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DOI：
10.1016/j.ijmachtools.2013.03.008
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发表时间：
2013-06
影响因子：
14
通讯作者：
M. D. Nguyen;Mustafizur Rahman;Y. Wong
中科院分区：
文献类型：
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作者：
M. D. Nguyen;Mustafizur Rahman;Y. Wong
由于去离子水具有较低的导电性，因此被用作双特性流体，将微细电火花加工和微细电解加工结合在一起，形成了一种独特的加工工艺，称为SEDCM铣削。为了在加工过程中实现放电和电化学反应，加工参数如进给速度和层深的选择是最重要的。本文提出了一种分析模型，用于确定复合加工过程中材料去除机制转变的临界条件。根据电极扫描表面时电化学反应所能溶解的材料层厚度，确定了三种不同加工模式的标准。然后利用双层理论、Butler-Volmer方程和法拉第电解定律预测了材料去除机制转变的临界进料速率。实验验证了所提模型的有效性。已经确定，SEDCM铣削只有在中等进给速度下才能实现。对于高进给速度，当电化学反应可溶解的材料层厚度小于微细电火花表面粗糙度时，将加工方式改为单独微细电火花铣削。相反，在低进料速率下，当电化学反应溶解层的厚度大于预设层深度时，材料的去除机制转变为纯微电解去除。此外，还发现当使用较高的层深时，SEDCM铣削所需的进给速度较低，因为每次进给的火花需要去除更多的材料。
Owing to its slight conductivity, deionized water has been used as a bi-characteristic fluid to combine micro-EDM and micro-ECM milling in a unique machining process which has been named as SEDCM milling. To attain both electrical discharge and electrochemical reaction during machining, selection of machining parameters such as feedrate and layer depth has been empirically observed to be of prime importance. This paper presents an analytical model to identify the critical conditions for transitions of material removal mechanisms in this hybrid machining process. The criteria for three distinct machining modes micro-EDM/SEDCM/micro-ECM milling are determined based on the thickness of material layer that electrochemical reaction could dissolve when the electrode scans over the surface. The critical feedrate for transitions of material removal mechanisms are then predicted using double layer theory, Butler–Volmer equation and Faraday's law of electrolysis. Experimental tests were also performed to validate the proposed model. It has been established that the SEDCM milling is only attained at moderate feedrate. For high feedrate, machining mode is changed to micro-EDM milling alone when the thickness of material layer that electrochemical reaction could dissolve is smaller than the roughness of micro-EDMed surface. On the contrary, for low feedrate, material removal mechanism is converted to pure micro-ECM when the thickness of layer dissolved by electrochemical reaction is higher than the preset layer depth. In addition, it is also found that lower feedrate is required for SEDCM milling when higher layer depth is used because more material needs to be removed by the sparks in every feed.