Simultaneous micro-EDM and micro-ECM in low-resistivity deionized water

Micro-EDM and micro-ECM are two suitable machining processes for micro- and nano-fabrication. Each process alone has some undesirable effects which confine its capability. By appropriate combination of these two processes, the adverse effects can be significantly mitigated. However, micro-EDM operates in non-conductive dielectric fluid whereas micro-ECM employs conductive electrolyte. Because of two rather divergent requirements, micro-EDM and micro-ECM are usually used sequentially. By using low-resistivity deionized water, which exhibits both characteristics of a slightly conductive fluid and a dielectric fluid, this study aims to combine micro-EDM and micro-ECM in a unique hybrid machining process to achieve improved performance in both surface finish and machining accuracy. Through the analysis of material removal phenomenon in micro-EDM using low-resistivity deionized water, it is found that there is a conversion of material removal mechanism from mere micro-EDM to hybrid micro-EDM/ECM when low feedrate is applied. Arising from this observation, a novel hybrid machining process, named as simultaneous micro-EDM and micro-ECM (SEDCM), has been developed. Three key factors of SEDCM, namely low-resistivity deionized water, low feedrate and short voltage pulses, are identified.

► Conversion of material removal mechanism is found when low feedrate is applied in micro-EDM using deionized water. ► A novel hybrid process, simultaneous micro-EDM and micro-ECM (SEDCM), is presented. ► Three main factors of SEDCM are identified: low-resistivity deionized water, low feedrate and short voltage pulses.