Surface microstructures can provide various functionalities, and wettability is a typical surface property that can be controlled by the surface textures. This study attempted to fabricate hierarchical microstructures through ultrasonic-assisted face milling (UAFM) to change the surface functionality by specifically focusing on the wettability. The fabrication involved the use of an ultrasonic generating spindle and a self-designed diamond tool. The locus of the tip of the diamond tool was computed based on the equation of motion, and the micro- and macrostructures are illustrated in this paper. The structures were confirmed through observations using a white-light interferometer. The wettability on six zones of the processed area was measured, and the results indicated that the central zone of the UAFM surface became hydrophobic, whereas the edge zone became hydrophilic.

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