Dual nozzle vortex tube cooling system (VTCS) is developed to improve the machinability of Ti-6Al-4V where cold-compressed CO2 gas is used as a coolant. The cooling effect is produced by the process of energy separation in the vortex tube and the coolant is supplied into the machining zone to remove the generated heat in machining. In this study, the responses such as cutting force (Fz), cutting temperature (Tm), and surface roughness (Ra) are analyzed by considering coolant inlet pressure, cold fraction, and nozzle diameter as input variables. Further optimization is performed for the input variables using the genetic algorithm technique, and the results at optimum conditions are compared with those of dry cutting. From the results, lower cutting force is observed at lower coolant pressure and cold fraction and higher nozzle diameter. The cutting temperature is minimized by increasing coolant pressure and cold fraction and by decreasing nozzle diameter. A better surface finish is observed at high coolant pressure and cold fraction and lower nozzle diameters. It is observed from the response surface method (RSM) that the coolant pressure is most significantly affecting all the responses. At optimum conditions, the cutting temperature and surface roughness are 35.6% and 66.14%, respectively, lower than dry cutting due to the effective cooling and lubricating action of the CO2 gas, whereas cutting force observed under the VTCS is 18.6% higher than that of dry cutting because of the impulse force of the coolant VTCS and thermal softening of the workpiece in dry cutting.

A new cooling approach using a vortex tube and carbon dioxide (CO2) gas has been proposed in this work. This approach is developed to minimize the cutting temperature during the machining of titanium alloy. The cutting force, surface roughness, and cutting temperature are measured by varying input flow parameters such as pressure, cold fraction, and temperature of CO2 gas. This approach is observed to be better compared with dry cutting in reducing the cutting temperature and surface roughness. It is also observed that the cutting temperature and surface roughness are reduced with an increase in CO2 gas pressure and cold fraction and a decrease in CO2 temperature. Cutting force increased with a rise in the pressure and cold fraction and with a decrease in the temperature of CO2 gas. The response surface methodology is used to predict and optimize the cutting temperature, cutting force, and surface roughness, respectively. The validation of the results is carried out by performing the experiment at optimized input parameters.

High cutting temperatures are reported in the machining process because of a large amount of generated heat, which reduces the dimensional accuracy and quality of the machined surface. This paper presents a new methodology to design a carbon dioxide (CO2)-based cooling system in which the cooling effect is produced by using the Joule–Thomson effect during machining of Ti-6Al-4V. The finite element method and computational fluid dynamics are used to predict the tooltip temperature in machining, supply conditions of the coolant, and design parameters. The theoretical heat transfer rate of the tool and workpiece is compared with the simulated value to validate the model. After the validation, the turning experiments of dry machining and CO2-cooled machining are performed under constant cutting parameters. In this experimentation, the coolant supply conditions used are taken from the simulation. From the experimental results, it is observed that the CO2 cooling system provides a reduction in cutting temperature (46.66 %), flank wear (10 %), and surface roughness (46 %) compared with dry machining. However, cutting force is increased (about 33.33 %) because of the pressurized CO2 gas focused on the cutting tool.

The study on the machinability of titanium alloys provides new ways to minimize the difficulty levels of machining the alloys due to substantial heat accumulation. To improve machinability, pivotal factors such as heat accumulation and cutting temperature must be regulated. In this study, a turning operation was performed on Ti-6Al-4V and the cutting temperature was reduced by supplying cooled CO2 gas through a vortex tube connected with two nozzles. Variations in cutting force, cutting temperature, and surface roughness with cutting speed, feed, and depth of cut were recorded. Subsequently, responses were compared for single nozzle vortex tube, dry, and compressed air environments at different cutting speeds. Cutting force and surface roughness followed a similar trend which increased with decreasing speed, and increasing feed and depth of cut. The cutting temperature increased with all three variables. The proposed cooling system provided better results in terms of cutting temperature and surface roughness, while a marginally higher cutting force was observed compared to dry cutting

No abstract