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Surface Finishing Tutorial

#036 Electrolytic Etching - Electrolytic Etching Applications - 5

Category : Metal etching
April 2, 2010
8) Electrolytic micro-hole machining

Although micro-holes can be created with electrodes made of small diameter metal tubes with outer insulation, the insulating of this outer surface is difficult and the insulation at the tip is easily broken during the process.

In order to overcome this shortcoming, a scheme shown in [Fig.1] is used. The surrogate electrode is made of an insulating material such as glass tube with a fine tip, connected to the cathode camber with a flexible tube.

[Fig.1] Electrolytic micro-hole machining

The actual electrode (metal rod or plate) is immersed in the electrolyte within the cathode chamber. Approximately one atmospheric pressure is applied to the cathode chamber to cause the electrolyte to fill and flow from the fine tip (fewμm) of the surrogate electrode.

The tip is placed very close to the work piece and the electrical current applied. The electrolytic etching occurs only at around the tip, and by advancing the tip position into the work piece as the etching progresses, the micro hole can be bored.

Since a constant electrical current will remove a certain amount of material in a certain amount of time, a hole with a constant diameter can be created by advancing the tip at a constant speed.


9) Electrolytic transcription

This is a process of transcribing patterns on a rotating drum onto a flat substrate, and can be applied to create printed circuits and etc.

The original pattern on a metallic plate is created by photo etching, first. Recesses of the original pattern is filled with non conductive material such as epoxy. This plate is affixed to a rotating drum, and the work piece is mounted on a slide table that reciprocates in linear motion under the drum. The gap distance between the two is maintained at 0.15mm and electrolyte is introduced into the gap while an electrical current is applied. By synchronizing the drum's rotation and the slide table, the pattern on the drum will be transcribed onto the work piece.

The used electrolyte carrying the electrolysis process byproduct will travel on the work piece and is collected by a tank below. Dissolved metals in the collected electrolyte are removed by an ion exchange resin filtration system and the electrolyte is put back into a reservoir tank for reuse.

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