Experimental study on surface generation in vibration-assisted micro-milling of glass

Micro-milling of glass is a technique to fabricate micro-optics with complex geometry using a defined cutting edge. This paper presents the experimental study on the surface generation in vibration-assisted micro-milling of a BK-7 optical glass. A piezoelectric-actuated 2D vibration stage with flexure design is developed to apply vibration assistance on the workpiece in the micro-milling process. The effects of vibration direction, vibration amplitude and frequency on the surface roughness and profile are determined from a series of vibration-assisted micro-milling experiments. It is concluded that the vibration applied in normal direction has a major effect on the improvement of surface quality. The vibration assistance enhances the brittle-ductile transition of glass material and therefore reduces the damage on the machined surface. Higher vibration frequencies improve the surface quality by reducing the waviness on the surface.