Thermal analysis of drilling in titanium under flood and cryogenic cooling using coupled CFD and FEM

Measuring drill temperature in drilling in the presence of cutting fluids is always a challenge. Therefore, numerical techniques have been adopted to study heat generation during drilling. In this work, the distribution of temperature in drilling of titanium workpiece under various cooling strategies was investigated by developing a coupled computational fluid dynamics (CFD) and finite element model (FEM). The CFD model simulates some of the realistic aspects of drilling, such as cutting fluid boiling in the vicinity of drill cutting edges and rotation of the drill inside the fluidic domain. The CFD model gives temperature distribution and flow properties of cutting fluids around drill cutting edges. The temperatures, stresses, and cutting forces encountered during drilling were evaluated using 3D FEM. Chip formation was modelled by combining material model with Johnson Cook plasticity, and failure models. It was evident that coolant vapor volume fraction is the highest around drill cutting edges, and increases with cutting speed. Liquid nitrogen with low boiling point, undergoes a rapid phase change during drilling. A spiral streamlines as well as reversing and circular streamlines of coolants were observed. In the flood and cryogenic cooling conditions, the coolant velocities range from 0.71–1.05 m/s and 0.79–1.15 m/s, respectively. The cryogenic and flood conditions reduce the drill maximum temperature by 33–50 % and 25–38 %, respectively, as compared to dry condition. The numerically predicted temperature is ~4–12 % off the average experimental temperature. The numerical thrust and torque lie within ~2–18 % of the experimental values.