Towards understanding performance enhancing mechanism of micro-holes on K9 glasses using ultrasonic vibration-assisted abrasive slurry jet

Abrasive slurry jet (ASJ) machining technology is highly desirable to meet the increasing demand for machining of micro-structures on difficult-to-machine materials, like ceramics and glasses. However, by employing the relatively low pressure ASJ with small abrasive particles usually results in W-shaped bottom surface of micro-hole while to use the relatively large abrasive particles involved in ASJ could eliminate the W-shaped profile but the bottom surface quality seems not to be good. In this paper, the ultrasonic vibration-assisted abrasive slurry jet machining of micro-holes on K9 glasses was proposed to enhance the machining performance. It is found that the effect of ultrasonic vibration on the particle trajectories and the resultant particle dynamic impact process in the stagnation zone significantly contributes to the performance enhancement of micro-hole, including the material removal rate and bottom surface morphology, rather than its effect on inducing the additional brittle erosion due to the less increase of particle impact energy. Further, the bottom surface quality has also found to be enhanced because the periodical vibration of the workpiece would affect the fluid streamlines in the stagnation where it not only enables more particles to participate the material removal process but also drives more after-impact particles to roll over and smooth the machined surface due to the viscous flow induced secondary or multiple particle impacts, and hence, resulting in a smoother surface.