Micro-texturing on free-form surfaces using flexible-electrode through-mask electrochemical micromachining

Abstract

Abstract Surface micro-texturing deals with the issues pertaining to various fields of engineering for enhancing essential functions such as tribological, wetting, biocompatibility, sustainability, cleanliness, etc. Among all the aforementioned sectors, micro-texturing of curved/free-form large areas is getting huge attention, e.g. micro-textures on artificial biomedical implants enhance sustainability and life cycle by better implant-tissue interface, cell-adhesion, and cell proliferation. Due to growing awareness towards the significances of micro-texturing, presently a lot of thrusts are being given on innovations employing surface textures on free-form/curved surfaces. The paper proposes a porous and flexible electrode based through-mask electrochemical micromachining (TMECMM) in which surface of any curvature can be textured by adapting the shape of the surface. A 3-D numerical simulation of the TMECMM texturing executed in COMSOL to analyze the effect of current density and topology of micro-textures. The minimum pitch of the micro-features in mask is determined through analysis of overlap of current density with the help of developed model. High resolution-reusable masks with micro-features arrays are fabricated using a two-step laser beam machining process. These masks are employed in-between the flexible electrode and target metal surfaces for localized anodic dissolution for texturing. The comparison of response surface methodology (RSM) based experimental and simulated results shows a close fit (and same trends) with respect to diameter and depth of micro-dimples array. The capabilities of the developed device are showcased by machining various types of texture arrays of micro-dimples, straight micro-channels, and turbulated micro-channels on flat, cylindrical, spherical, and free-form surfaces of SS304.