Electrical discharge micro-texturing using compound tool electrodes for tribological and wettability applications

Abstract

The present work consists of large-area surface texturing through die-sinking electrical discharge machining (EDM) using compound tool electrodes. The compound tools were machined through the wire electrical discharge machining (WEDM). The micro-textured surfaces incorporating array of nearly square/circular-shaped micro-dimples, rectangular micro-channels and square micro-pillars were analysed for their wetting properties. An increase in water contact angle (CA) indicated higher water repellence for textured surfaces with respect to the untextured ones. Further, improved frictional behaviour was elicited through tribological analysis via the ball-on-disc test, revealing a lower average coefficient of friction (CoF) compared to the untextured surface. The wear volume of textured surfaces (micro-channels and micro-pillars) exhibited a slightly higher value with respect to the untextured surface, which can be ascribed to the stress concentration from microfeatures. However, the micro-dimpled textured surface showed a relatively lower wear volume, presenting a suitable micro-texture for improved tribological characteristics.

Die-sink EDM texturing to fabricate hydrophilic and wear resistant surface

“…Because the wetting behavior is fully dependent upon the texture geometry, shape, orientation, etc. [21,27]. As discussed in the surface morphology section sample 4 has less deviation in V groove shape as compared to the other one.…”

“…Hence a textured surface behaves like a wear-resistant agent. Moreover, there is the formation of a load-bearing agent that acts as a third particle for the wear mechanism due to the entrapment of wear debris into the V-groove channels [21]. Sample 4 exhibits the lowest COF value among all textured surfaces.…”

“…Singh et al [21] have fabricated microchannels, micro dimples, and micropillars with the use of compound tools on the surface of brass material using die sink EDM. Their reports showed that all the textured surface has a low coefficient of friction (COF) (COF ranges from 0.13 to 0.19) as compared to brass material (COF of 0.36).…”

Investigation of the Influence of Machining Parameters and Surface Roughness on the Wettability of the Al6082 Surfaces Produced with WEDM

“…The dual-scale morphology surfaces can give a rise to hydrophobicity [25]. Such hierarchical surface textures can be fabricated by utilizing a textured electrode in sink EDM [26,27], by applying a coating from the electrode to the surface during discharging [28,29] or by controlling the wire cut path in order to create various geometrical features with WEDM [30][31][32]. Applications of hydrophobic surfaces created with EDM and WEDM include improved heat transfer surfaces [33,34] anti-bacterial surfaces [35], anti-fouling surfaces [36,37], corrosion resistance surfaces [38], and surfaces for anisotropic wetting [39].…”

Enhancing the hydrophobicity of Ti–6Al–4V through multi-level electrical discharge texturing

“…Therefore, the EDMM process is envisaged to be an appropriate competitor for micro-textures machining; thus, it is indispensable to sightsee the competencies of the EDMM for surface texturing. A compound tool comprising an array of tools in a single electrode has been employed to simultaneously fabricate micro-features on large-area through the EDM process [29]. Besides single-level textures, there is a need for hierarchical and multi-level textures, which are getting acceptance in various surface modification and differential finishing applications.…”