Modulated vibration texturing of hierarchical microchannels with controllable profiles and orientations

Hierarchical microchannels, which consist of the primary channel formation and superimposed secondary nanostructures, are attracting ever-increasing attention due to their unique capacity to enhance and modify the surface characteristics and functional performance. The mechanical machining methods for microchannel fabrication, such as micro-milling and diamond turning, can achieve high material removal rates without changing material properties. However, they have limited capacity to control the channel cross-section profiles and shapes due to the relative size between the channel dimension and tool geometry. This study proposes a new cutting-based approach for the fast and cost-effective fabrication of hierarchical microchannels with controllable profiles and orientations by utilizing modulated elliptical vibration texturing. The modulation motion is adopted to form the primary channel in an incremental approach, while the elliptical vibration texturing is utilized to create micro/nano-scale secondary textures. By controlling the tool modulation trajectory, hierarchical dimple arrays with controllable cross-section profiles are first demonstrated. Then, by programming the layout of dimples to adjust the overlapping ratio between each cut, channels can be formed with arbitrary cross-section profiles and orientations. The efficacy of the proposed process has been demonstrated through numerical simulation and experimental results. Hierarchical microchannels with straight and curving shapes, as well as different cross-section profiles (sinusoidal, triangular, trapezoidal), have been presented.