Influence of Electrode Profiles on Electrical Discharge Machining of Titanium

Electric discharge machining (EDM) is an effective manufacturing technique that enables the production of parts made of hard materials with complicated geometry that are difficult to produce by conventional machining processes. EDM is a process of eroding material by transient action of electric sparks on electrically conductive materials, one being the workpiece the other being the electrode immersed in a dielectric fluid and separated by a spark gap. The EDM ability to control the process parameters to achieve the required dimensional accuracy and surface finish has placed this machining operation in a prominent position in industrial applications. This work reports on the different electrode profiles on the machinability factors of surface roughness (Ra) and material removal rate (MRR). The machining factors used in this study are the current (I), on-time and off-time. Based on the experimental results influence of the electrode profile on the responses were made and reported in this study.

Numerical Simulation of AC Electrothermal Microfluidic Pumping

AC electrokinetic forces, such as AC electroosmosis (AC EO), AC electrothermal (AC ET) and dielectrophoresis (DEP) have been intensively investigated in manipulation of microfluids and micro/nanoparticles. AC EO effects are prone to manipulate relatively dilute electrolytes while AC ET effects extend the manipulation into conductive fluid domain. In the case of pumping high conductivity fluid, electric traveling wave signals on interdigitated electrode arrays and single-phase AC signals on asymmetric electrode structures are the two reported methods for AC ET based fluidic manipulation. This paper presents numerical simulation of the AC electric field induced electrothermal fluidic motion and pumping capacity of high conductivity fluids with stepped asymmetric electrode arrays. We investigated the effects of electrode profile and layout on pumping action and temperature rise distribution. Forward pumping mode and backward pumping mode are identified theoretically and numerically. Compared with the planar asymmetric electrode arrays, utilization of steps on electrode profile can result in significant improvement on the pumping capacity.