Relationship between quartz crystal orientation and the surface quality obtained by ultrasonic machining

Ultrasonic machining (USM) of natural quartz is investigated in relation to crystal orientation. The rate of cutting was measured along directions perpendicular to X-, Y-, Z- and AT-cut planes. Surface profilometry was carried out on lateral surfaces achieved by USM. It is shown that cutting rate and surface roughness are dependent on crystal orientation. These dependencies are preliminary discussed in relation to indentation fracture mechanics and fracture toughness anisotropy of natural quartz. Scanning electron microscopy analysis shows that brittle microcracking is the main wear mechanism involved with material removal.