Optimization of process parameters of small hole dry drilling in Ti–6Al–4V using Taguchi and grey relational analysis

•Thrust forces, circularity, overcut and taper were measured for Ti–6Al–4V.•Optimization was carried out by Taguchi method and grey relational analysis.•Mathematical modeling was performed by using regression analysis.•Unlike convention, thrust force decreased with increasing feed rate.•Air pressure and spindle speed proved to be the most significant parameters. The growing demand for miniaturization of systems necessitates the production of smaller components with high dimensional accuracy. In this experimental investigation, through holes were machined in a Ti–6Al–4V plate of 0.4mm thickness using twisted carbide drill bits of 0.4mm diameter by conventional dry drilling. The Taguchi’s experimental design and Analysis of Variance (ANOVA) techniques have been implemented to understand the effects, contribution, significance and optimal machine settings of process parameters, namely, spindle speed, feed rate and air pressure. The performance characteristics of the small hole drilling were evaluated through thrust force, overcut, circularity and taper. Multi-performance optimization of the process parameters was realized by using grey relational analysis and mathematical modeling was done by regression analysis. The outcome of this research revealed that spindle speed and air pressure have the most significant impact on the dimensional accuracy of the hole; spindle speed and feed rate controls the thrust force.