Removal mechanism of machinable ceramics and theoretical model of cutting force in turning operation
The removal mechanism of machinable ceramics in turning was studied, and a theoretical model of cutting force based on energy theory was proposed. Based on the turning test of machinable ceramics and kinematics analysis of the tool-workpiece system, a model of tool-workpiece contact zone considering the tool tip arc radius was established. The crack propagation path and three stages of the crack development were analyzed from the stress perspective. Then the energy of the crack system was studied, and the brittle fracture energy which is more suitable for brittle materials was put forward. Based on the principle of energy conservation, a correction theoretical model of cutting force was established, which was verified by turning experiments of machinable ceramics. The results indicated that the predicted values of the model were in good agreement with the experimental values. Both theoretical model and experimental results demonstrated that the cutting force decreased as cutting speed increased, and increased as cutting depth and feed rate increased. This model enabled an in-depth understanding of the interaction action between the cutting tool and work materials involved in the turning of machinable ceramics.