Modeling the dependency of edge chipping size on the material properties and cutting force for rotary ultrasonic drilling of brittle materials

• A new edge chipping mechanism was proposed by considering both effects of cutting force and subsurface cracks induced by machining.
• An analytical model was developed to predict edge chipping size formed during rotary ultrasonic drilling of brittle materials.
• Rotary ultrasonic drilling generates weaker cutting forces and smaller subsurface damage, consequently, smaller edge chips.

Edge chipping induced by rotary ultrasonic drilling (RUD) restricts the applications of brittle materials. It should be possible to reduce or eliminate edge chipping by optimizing the process parameters based on efficient theoretical modeling of the size of the edge chip. However, to date, no publications are available on the predictive modeling of edge chipping during RUD of brittle materials. This paper presents an analytical model for predicting the edge chipping size during RUD of brittle materials by considering both effects of cutting force and subsurface cracks induced by machining on the occurrence of edge chipping. The relationships between the edge chipping size, processing variables (material properties and ultrasonic amplitude), and the cutting force were established theoretically. The coefficients in the model were obtained by conducting RUD tests on K9 optical glass specimens. Subsequently, the model was validated by conducting RUD tests on sapphire specimens. Using this model, the edge chipping size can be predicted during RUD of brittle materials. The experimental and predicted results were in good agreement.

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