Coolant flow in drilling titanium considering two phase boiling

• In-situ monitoring of cutting edge temperature in the presence of coolants in the titanium drilling was obtained by using computational fluid dynamic (CFD) model. • CFD model gives fluid flow characteristic and temperature distribution around drill cutting edges under flood, cryogenic and mist cooling conditions. • The boiling of the cutting fluids in the heated region of drill was modeled by using Volume of Fluid (VOF) multiphase model. • The highest vapour fraction of cutting fluids was observed around chisel edge in flood and cryogenic cooling , and at cutting edge corners in thin and thick mist cooling. • Peak temperature in drilling drops by 32%, 36%, 38% and 48% in flood, thin mist, thick mist and cryogenic cooling. • The predicted temperatures lie within ∼4-18 %, of the experimental temperature. In drilling titanium alloys, significant heat build-up on drill cutting edges due to insufficient heat dissipation raises tool temperature, leading to its rapid wear. Researchers have experimented with a variety of cooling methods to reduce temperature as well as tool damage. The in-situ monitoring of temperature of cutting edges presence of fluids in the drilling is difficult. Therefore, computational fluid dynamics (CFD) based model is proposed to investigate the temperature distribution along the drill cutting edges, and the flow characteristics of the cutting fluids such as water, mist and liquid nitrogen around the cutting edges. The boiling of cutting fluids near the cutting edges of the drill was considered by using Volume of Fluid (VOF) multiphase model in the analysis. The mist cooling was handled using a discrete phase model, and the Euler–Lagrangian technique was employed to deal with interactions between air and droplets. The highest vapour volume fraction of coolants was detected along the chisel edge of the drill cutting edge in flood and cryogenic cooling conditions. Whereas, for mist cooling, maximum vapour volume fraction of coolants was detected end of cutting edges. As the liquid nitrogen has an unusually low boiling point, it undergoes a quick phase change during the initial stages of drilling. Coolant velocities around the cutting edges in flood, cryogenic, and thick-thin mist cooling were 0.03–0.12 m/s, 0.7–0.9 m/s, 4–9 m/s, and 6–13 m/s, respectively. The maximum temperature of the drill drops by 45–48%, 32–38%, 29–36%, and 24–32% in cryogenic, thick mist, thin mist and flood conditions, respectively, over the dry condition. The numerically predicted temperature lies within an error of ∼4–18% of that of the average experimental temperature. .