Micro Fabrication on Glass in the Abrasive Water Jet Process

Abstract

A new manufacturing process with abrasive water jet is proposed to fabricate micro channels or dimples on glass. Masks having exposed areas cover the surface so that the covered areas cannot be machined. Because the width of the exposed areas is much smaller than the diameter of the jet nozzle, tapers are made in the cross section of the masks so that abrasive slurry can reach the exposed surface. Abrasive slurry is mixed with water supplied by a low-pressure pump in a water jet nozzle. When abrasive water flows onto the surface vertically between the taper-shaped masks, stagnation is made right under the nozzle. Because the flow velocity is low in stagnation, brittle fracture does not happen on the machined surface. The vertical flow also changes to the horizontal direction at a high velocity out of the stagnation. Abrasive particles, therefore, machine the surface in the horizontal direction at a high velocity. The jet nozzle moves back and forth for several times along the exposed area. A V-shaped groove, which is a depth of 2.5µm and a width of 20µm, can be machined on the surface of fused silica. A micro fabrication machine is made to fabricate micro grooves at the specified positions and angles. It is shown that the machine works well to make micro patterns on the surface in some examples. A machining example proves that the machined shape can be predicted with computational fluid dynamics