Investigation on grinding force and machining quality during rotary ultrasonic grinding deep-small hole of fluorophlogopite ceramics

Fluorophlogopite ceramics is widely used in the fields of aerospace and biomedicine, and the machining of deep-small hole for fluorophlogopite ceramics is a focus in the field of precision and ultra-precision machining. In this work, the trajectory and brittle-to-ductile transition depth of single abrasive during rotary ultrasonic grinding process were analyzed. The rotary ultrasonic grinding and common grinding tests of deep-small holes for fluorophlogopite ceramics were performed on an ultrasonic vibration and precision machining center. The axial grinding force was obtained by wavelet denoising, the roundness deviation was calculated by using Canny and gray level detection methods, and the internal surface roughness was measured by using laser scanning confocal microscopy. The experimental results indicated that compared with the common grinding, rotary ultrasonic grinding could effectively decrease the grinding force, roundness deviation, and the value of surface roughness. In addition, the grinding force, roundness deviation, and the value of surface roughness decreased as the spindle speed and ultrasonic power increased, and they increased as the feed speed increased. This work was of significance for realizing the high efficiency and precision machining of deep-small holes of the hard-brittle materials.