Abstract:
An effective cooling approach with appropriate process parameters can enhance the machinability as well as productivity. In this regard, this study focuses on enhancing the machinability of widely used Ti-6Al-4V alloy with the use of high-pressure coolant jets compared to dry milling. A novel rotary applicator has been designed and developed to feed high-pressure coolant jets without any drastic change of solid end mill tool. In order to estimate the optimum design parameters for the proposed cooling approach, Taguchi based DoE has been integrated with CFD analysis. The optimum design parameters for the rotary applicator have been selected as 80 bar pressure, 3.0 L/min oil flow rate, and 0.50 mm nozzle dia. while keeping other factors such as inclination angle, radial distance, and jet inlet to tool distance constant. Average cutting temperature, resultant cutting force, mean surface roughness, and tool wear are all taken into account in evaluating the machinability of various speed-feed combinations. Compared to dry milling, in rotary high-pressure cooling (RHPC), cutting temperature, cutting force, and surface roughness are reduced by 37.56 %, 21.5 %, and 41.3 %, respectively that may be attributed by the cooling and better lubrication effect. Similarly, flank wear is considerably decreased with extended tool life (9 min). Regarding to multi-response optimization, 32 m/min cutting velocity, 26 mm/min table feed rate, and 0.60 mm depth of cut has been selected as the optimal process parameters. Beside this, the complicated milling process has been simulated by using ABAQUS/EXPLICIT 6.14, which took into account the process's dynamic behavior such as variable boundary conditions, Johnson-Cook plastic flow stress model and damage model, thermo-mechanical coupling, film thickness coefficients, load constraints, Coulombs’ friction law with hard contact behavior for the detail analysis of temperature distribution. Finally, the simulated results are cross-checked with the real-world experimental results for the validation of the used model. A satisfactory agreement has been obtained with a margin of error of 14.8%. Predicting cutting forces is essential in such machining process since it affects significantly to better surface integrity as well as longer tool life. To assess cutting forces during milling Ti-6Al-4V alloy, an integrated analytical model based on Armarego-Oxley's predictive machining theory and modified Johnson-Cook's material law is proposed incorporating the cooling effect of HPC. The proposed model's viability is confirmed by the real experiment data in milling Ti-6Al-4V alloy. Experimental studies have demonstrated strong agreement. Lastly, a cost analysis is conducted to determine whether the suggested cooling method is economically
