Optimization of modulation-assisted drilling of Ti-6Al-4V aerospace alloy via response surface method

Abstract

The study concerned with optimization of modulation-assisted drilling (MAD) operation for a difficult-tocut material Ti6Al4 V was carried out via response surface method (RSM). Conventional drilling (CD) has been explored for comparison purposes. Experiments have been designed according to the Central Composite Design (CCD). The impact of machining input parameters on surface roughness (SR), machining power consumption, and tool wear (TW) was investigated for both cases. Pilot experiments were carried out to find out the best modulation range. Further drilling experiments were carried out varying feed rate, spindle speed, and tool diameter. Multiple regression analysis using RSM established relationships between these parameters and responses. ANOVA was used to develop and test the mathematical models. The models were effective in predicting the responses for MAD of Ti6Al4 V. The optimum drilling parameters are a tool diameter (TD) of 2 mm, feed rate (FR) of 0.030 mm/rev and spindle speed (SS) of 2176.87 rpm. SEM and EDS analyzes were performed to investigate the machined surfaces. From the study, it can be concluded that MAD is a promising machining process for difficult-to-cut materials with comparatively less thrust force, surface roughness and tool wear. Abbreviations: SD: Standard deviation; SS: Spindle Speed; TF: Thrust Force; BUE: Built-Up-Edge; PRESS: Prediction error sum of squares; TD: Tool Diameter; CD: Conventional Drilling; CV: Coefficient of variance; MAD: Modulation-Assisted Drilling; SR: Surface Roughness; VAM: Vibration-Assisted Machining; TW: Tool Wear; RSM: Response Surface Methodology; ANOVA: Analysis of Variance; FR: Feed Rate; SNR: Signal-to- Noise Ratio; FW: Flank wear