• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.43-49
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• 2003

In this study, micro electrochemical machining method was introduced for accomplishment the fabrication technology of functional parts and smart structures using the Ni-Ti shape memory alloy. From the experimental result, the micro part which has very fine surface could be achieved by use of micro electrochemical process with point electrode method. Concretely, the optimal performance of micro electrochemical process in Ni-Ti SMA was obtained at the condition of approximately 100% of current efficiency and high frequency pulse current. That is, much finer surface integrity and shape memory effect can be obtained at the same condition mentioned above.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.308-314
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• 2011

In micro electrochemical machining (micro ECM), machining conditions have been determined to maintain a small side gap and to machine a workpiece stably However, machining speed is slow. To improve machining speed while maintaining the form accuracy, the paper investigates machining parameters such as pulse amplitude, duty ratio, pulse on-time, and the electrolyte's temperature and concentration. The experiment in this study shows that the electrolyte's concentration is the key factor that can reduce machining time while maintaining the form accuracy Micro square columns were fabricated to confirm the machining parameters' effects.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.942-945
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• 2001

Pulse electrochemical micromachining offers significant improvements in dimensional accuracy as compared with conventional electrochemical machining. One primary issue in pulse electrochemical micromachining is to identify and control machining depth as well as interelectrode gap size. This paper presents an identification method for the machining depth by in-process analysis of machining current and interelectrode gap size. The inter electrode gap characteristics, including pulse current, effective volumetric electrochemical equivalent and electrolyte conductivity variations, are analysed based on the model and experiments.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.146-152
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• 2006

In micro electrochemical machining (ECM), electrodes should be prevented from unfavorable oxide and Passive layer formation on the machined surface or overall corrosion of the entire surface. Generally, metal electrodes corrode, passivate or dissolve in the electrochemical cell according to the electrode potential. Therefore, each electrode must maintain its stable potential. Tn this paper, the stable electrode potentials of tool and workpiece were determined using the potentiodynamic polarization test and verified experimentally considering machining stability and surface quality. Stable workpiece electrode potentials of two different passive materials of 304 stainless steel and nickel were determined in the 0.1 M sulfuric acid. Experimental results show good machined surface and fast machining rate using the determined electrode potentials.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.601-602
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• 2008

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.370-375
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• 2010

Tungsten carbide microshaft is used as micro punch, electrode of micro electro discharge machining, and micro tool because of its high hardness and rigidity. In this research, tungsten carbide microshaft was fabricated using electrochemical machining. $H_2SO_4$ solution was used as the electrolyte because it can dissolve tungsten carbide and cobalt simultaneously. Experimentally studied were the effects of electrolyte concentration, machining time, and machining voltage on material removal rate and the shape of the microshaft. To eliminate the effects of bubbles and metal corrosion layer on microshaft shape, the machining was performed below the electrolysis voltage. Three step electrochemical process was suggested to fabricate the straight tungsten carbide microshaft. As a result, a straight tungsten carbide microshaft of $30{\mu}m$ in diameter and $500{\mu}m$ in length was obtained through the proposed three step electrochemical process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.151-152
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• 2007

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.32-39
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• 2003

Pulse electrochemical machining process with high or low current density may produce a non-lustrous surface on workpiece surface. The usual polishing process to remove a black layer from the surface has been hand polish the part. But the milli-to-micro meter scale structure formed by the electrochemical machining process may be destroyed while polishing process. The application of ultra short voltage pulses based on the analysis of electrical double layer charging process allows high resolution electrochemical machining and polishing. This technique was based on the specific polarization resistance from the comparison of ideal and experimental potential variation during short voltage pulses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1281-1284
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• 2005

In the micro electrochemical machining (ECM), unfavorable oxide/passive layer formation and overall corrosion of electrodes must be prevented. Generally, the stainless steel electrode corrodes, passivates or dissolves in the electrochemical cell according to the electrode potential. Therefore, the electrode must maintain stable potential. The stable electrode potentials of tool and workpiece were determined with the potentiodynamic polarization test and verified experimentally from the point of machining stability and machined surface quality.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.585-588
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• 2005

The dissolution characteristic of metal shows the different tendency according to the applied electrical potential, the kind of electrolyte and pH value, etc. In the micro electrochemical machining (ECM), unfavorable oxide/passive layer formation and overall corrosion of electrodes must be prevented. The anodic polarization curve of nickel has distinct three dissolution regions, i.e. two active regions and the transpassive dissolution region. In this paper, the stable electrode potentials of workpiece and tool were determined in sulfuric acid and hydrochloric acid solution, respectively. In each solution, different machining property was shown and possible electrochemical reactions were discussed. On the basis of this experiment, the methodology to obtain the proper electrode potential was suggested.