Development of a Ductile Machining Model in Ultrasonic Elliptical Vibration Turning to Improve the Cutting Behavior of Brittle Materials

Ultrasonic Elliptical Vibration Cutting (UEVC), as an advanced machining method, has attracted considerable attention for improving surface quality and expanding the ductile machining regime of brittle materials. In this study, a novel theoretical and experimental model is proposed to analyze ductile machining behavior in the UEVC process, aiming to quantitatively investigate the mechanism of increased ductile cutting depth (dc) in brittle materials. The proposed model is developed based on the analysis of uncut chip thickness (UCT), the distance from the transient surface to the target surface (DTSTS), and crack length (Cm). Model results indicate that the effective reduction of UCT relative to the nominal depth of cut (DOC) and maintaining an appropriate ratio between DTSTS and Cm play a key role in preventing crack propagation. Experimental tests were conducted on KDP crystals using a UEVC setup and single-crystal diamond tools to validate the predicted model. Data analysis revealed that the proposed model can accurately predict the critical transition between ductile and brittle machining regimes. By providing analytical and empirical relationships among vibration parameters, cutting depth, fracture toughness, and machining force, this study offers a foundation for optimizing ultraprecision machining processes of brittle materials such as KDP, ZnS, and Si in optoelectronic, laser, and semiconductor industries.

Keywords:

Ultrasonic Elliptical Vibration Cutting , Ductile Machining , Brittle Materials , Ductile Cutting Depth , Crack Prediction Model , Uncut Chip Thickness (UCT) , Distance from Transient Surface to Target Surface (DTSTS) , Dynamic Fracture Toughness