Experimental investigations into sharklet patterning using atomized dielectric fluid in the electrical discharge machining process

Abstract

Over time, researchers have drawn inspiration from nature to enhance the topographical features of metallic and non-metallic surfaces through micro- and/or nano-texturing. One such topographical pattern, known as the sharklet pattern, mimics shark skin to prevent bacterial adhesion and enhance water repellence. The electrical discharge machining (EDM) process offers several advantages for the fabrication of sharklet patterns, including greater dimensional accuracy, higher aspect ratios of machined features, and cost-effectiveness. However, the EDM process utilizing conventional dielectric systems, such as wet-dielectric and jet-dielectric, requires substantial amounts of dielectric fluid, thereby increasing costs and environmental impact. Atomized, that is, spray dielectric fluid, has the potential to mitigate the problems of substantial dielectric consumption and environmental concerns caused by it, besides enhanced productivity. This study investigates the performance of three dielectric fluids, that is, wet-dielectric, jet-dielectric, and atomized/spray dielectric, based on output parameters, including overcut and surface finish, in the machined features. Atomized or spray-EDM consistently outperformed other dielectric techniques, yielding greater results, especially at lower energy conditions. Further, atomized dielectric fluid in combination with a foil and zig-zag tools has been utilized for the fabrication of sharklet pattern, micro-channel, and diamond pillared surfaces on stainless steel-304 (SS-304). The wetting behavior of various micro-textures was analyzed using water contact angle measurements. Except for the diamond-textured surface, all other textured surfaces show a hydrophobic nature with the highest water contact angle of 137°. The biomimetic shark skin surface, with its hydrophobicity (a water contact angle of 118°), can exhibit better anti-biofouling characteristics than a smooth surface, highlighting the potential of spray/atomized-EDM for manufacturing effective and environmentally friendly antifouling textured surfaces.