Theoretical equation of cutting temperature for brittle materials in turning fluorophlogopite ceramics

Different from material removal mechanism in metals, the main form of material removal of ceramics is brittle fracture removal. Previous studies on fracture mechanics for brittle materials basically do not involve cutting temperature, and only static crack systems are discussed, without considering the kinetic energy of crack extension; however, in real turning processes, the problem of crack extension is within the domain of dynamic fracture mechanics. Therefore, kinetic energy is considered in energy balance equations. The work of cutting force is converted into surface energy, strain energy, kinetic energy and heat energy. According to the law on the conservation of energy in fracture process, the theoretical equation of cutting temperature for brittle materials in turning is established. Then, turning experiments on fluorophlogopite ceramics are conducted to verify the applicability of the theoretical equation. The theoretical values of metal model, ceramic model and experimental values are compared. Results show that the theoretical value of metal model has a very large deviation when used to predict the cutting temperature of ceramics; whereas, the theoretical value of ceramic model is basically with the same changing tendency as the experimental value. This indicates that the established theoretical equation is practical.