• 한국정밀공학회지
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• 제19권4호
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• pp.101-108
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• 2002

A specially-built EMM (Electrochemical Micro Machining) / PECM (Pulse Electrochemical Machining) cell, a electrode tool filled with non-conducting material, a electrolyte flow control system and a small & stable gap control unit are developed to achieve accurate dimensions of recesses. Two electrolytes, aqueous sodium nitrate and aqueous sodium chloridc arc applied in this study. The farmer electrolyte has better machine-ability than the latter one because of its appropriate changing to the transpassive state without pits on the surface of workpiece. It is easier to control the machining depth precisely by micrometer with pulse current than direct current. This paper also presents an identification method for the machining depth by in-process analysis of machining current and inter electrode gap size. The inter electrode gap characteristics, inc1uding pulse current, effective volumetric electrochemical equivalent and electrolyte conductivity variations, are analyzed based on the model and experiments.

• 한국생산제조학회지
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• 제24권3호
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• pp.314-319
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• 2015

Invar is a compound metal of Fe-Ni system contained 36.5% Ni. The characteristic of invar is that the coefficient of thermal expansion is $1.0{\times}10^{-6}cm/^{\circ}C$. It is approximately 10 times smaller than series of steel. Because of this low thermal expansion characteristic of Invar, it is used to shadow mask of display device such as UHDTV or OLED TV. In this study, pulse current from pulse generator instead of DC current is used to overcome the disadvantages of the conventional electrochemical machining. Pulsed current with different duty factor in PECM affect the precise geometry. Pulse electrochemical machining is conducted to machine the micro hole to the invar sheet with different duty factor. The machined shape and overcut of invar sheet with different duty factor is observed by optical microscope and scanning electron microscope (SEM).

• 한국기계가공학회지
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• 제16권5호
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• pp.141-149
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• 2017

Due to the inaccuracy of micro-machining, various special processing methods have been investigated recently. Among them, pulse electrochemical machining is a promising machining method with the advantage of no residual stress and thermal deformation. Because the cross section of the wire electrode used in this study is circular, wire-pulse electrochemical machining is suitable for micro-hole machining. By applying the response surface methodology, the experimental plan was made of three factors and three levels: machining time, duty factor, and voltage. The regression equation was obtained through experiments. Then, by referring to the main effect diagram, we fixed the duty factor and machining time with little relevance, and solved the equation for the target 900 microns to obtain the voltage value. The results obtained from the response surface methodology were approximately those of the target value when the actual experiment was carried out. Therefore, it is concluded that the optimal conditions for hole processing can be obtained by the response surface methodology.