Recent developments in the reverse micro-electrical discharge machining in the fabrication of arrayed micro-features

Abstract

High aspect ratio arrayed micro-structures and textured surfaces are required in diversified applications such as electrical contacts, printing heads, electrodes for micro-batteries, injection nozzles, nano-material delivery systems, biomedical implants, and hydrophobic surfaces. Reverse micro-electrical discharge machining (R-MEDM) process has a capability to fabricate such arrayed features on a variety of workpiece materials irrespective of their mechanical properties. R-MEDM is a variant of micro-electrical discharge machining (MEDM) process, key difference being, extruded arrayed features are fabricated in the R-MEDM process against the micro-cavities that are machined in MEDM. This article highlights the recent advances in process characterization and modelling of mechanics of the R-MEDM process. The focus of discussion is on comparing the process with the other micromachining processes presently available for the fabrication of arrayed micro-features. In addition, R-MEDM process characteristics in the fabrication of arrayed features on ‘easy’ and ‘difficult’ to erode materials are presented. It is understood that R-MEDM has comparable or in some cases better performance in the fabrication of arrayed features than the processes like micro-milling, micro-wire EDM, micro-wire electrical discharge grinding (EDG) and block EDG.

Evaluation of μEDM-drilling and μEDM-dressing performances based on online monitoring of discharge gap conditions

“…The essentiality of keeping the same initial area of contact is to make the comparative study between the μEDM-dressing and the μEDM-drilling more effective. A similar technique of maintaining equal area of contact has also been demonstrated by Mastud et al [9] 3. Equal number of contributing pulses (N p ): The N p for a particular segment in both the processes was kept identical, the reason being to effectively study the performance of the processes in an equally allowable machining progress.…”

“…In this regard, a comparative evaluation of the μEDM-drilling and μEDM-dressing based on the discharge gap monitoring could describe their process stability. An initial attempt was taken by Mastud et al [9] to compare the process mechanics based on the current and voltage signals. The work was basically a time-evolution-based characterization of normal discharge and short circuit percentage.…”

Macro Scale Arrayed Structure Fabrication using Reverse EDM

“…The surface roughness on the fabricated electrode by micro R-EDM varies between 0.3-2.7 µm R a . The root portion of the rod is found smoother compared to its tip which covers deposited carbon on it [13,14].In order to obtain such complex shape first it is required to fabricate the tool having exact replica of that shape. This shortcoming of EDM leads to the use of R-EDM.…”

Variation and artificial neural network prediction of profile areas during slant type taper profiling of triangle at different machining parameters on Hastelloy X by wire electric discharge machining

“…[1][2][3][4] These components have application in the manufacture of precision parts like injection mould dies, blanking dies, injection nozzles etc. [5][6][7] The traditional guide adjustment mechanism for tapering causes the wire to bend which increases wire cut, causes guide wear, incomplete flushing, etc. As the wire is flexible, it is subjected to deformation and many other parameters also cause imprecisions during machining.…”