Single-step meso/micro scale hierarchical surface-structuring using an innovative tool-based hybrid laser-electrochemical micromachining process

Abstract

In recent years, fabrication of varied topographies, hierarchical structures and multiscale textures has attracted the research interest. Single step fabrication of hierarchical structures at sub-mm or microscale still remains a challenge for machining processes. In this work, a novel tool based hybrid laser-electrochemical micromachining process is presented which combines laser and electrochemical process energies on same machining axis by means of a hybrid tool. The hybrid tool acts as both an ECM tool and a multimode waveguide for the laser. With this technology, generation of uniform dual-scale surface structures is realized in single step. These structures have a dual-scale hierarchical morphology. Array of hierarchical cavities have been fabricated by this process on Inconel IN718 using a 1.2 mm diameter tool. Process details have been presented and machined hierarchical cavities are analyzed. It is shown that by controlling the process parameters of both laser and ECM, the geometry and structure of these hierarchical cavities can be controlled. Overall, it is shown that the hybrid laser-electrochemical micromachining technology facilitates fabrication of hierarchical surface structures due to application of different process energies at different scales. Further scaling down of the features is possible with scaling down of hybrid tool dimensions using state of the art microfabrication techniques.