Array SS-3D Micro EDM by Using Array Tool Electrodes

Abstract

AbstractArray micro cavities are useful in many fields including micro molds, optical devices, biochips, and so on. Array SS-3D micro EDM has the advantage to machine complex 3D micro cavities in batch, using array micro tool electrodes with simple cross-sectional shape. In this study, the method of array SS-3D micro EDM is first verified by applying the array micro tool electrodes with square-cross-section offline-fabricated by LIGA (German acronym for Lithographie, Galvanoformung, and Ab-formung, meaning Lithography, Electroplating, and Molding) process. Furthermore, the machining errors caused by offline-fabricated array micro tool electrodes are analyzed in particular, and then a machining process of array SS-3D micro EDM is presented by using on-machine fabricated array micro tool electrodes. The array micro-electrodes are fabricated on-machine by the combined procedures including WEDG, array reverse copying, and tool electrodes’ end trimming. 9-array tool electrodes with Φ80 μm in diameter and 600 μm in length are obtained. Furthermore, the proposed process is verified by several machining experiments for achieving 9-array hexagonal micro cavities with top-side length of 300 μm, bottom-side length of 150 μm, and depth of 112 μm or 120 μm. In the experiments, debris hump is accumulated on tool-electrodes’ tips like the built-up edge in mechanical machining under the conditions of brass workpieces, copper tool electrodes, and dielectric of deionized water. The accumulated hump can be avoided by replacing the water dielectric by oil dielectric.KeywordsArray micro cavitiesMicro tool electrodeReverse copyingDebris humpBuilt up edge (BUE)