Optimal machining conditions for turning Ti-6Al-4V using response surface methodology

Machining titanium is one of ever-increasing magnitude problems due to its characteristics such as low thermal conductivity, modulus of elasticity and work hardening. The efficient titanium alloy machining involves a proper selection of process parameters to minimize the tangential force (F _z) and surface roughness (R _a). In the present work, the performance of PVD/TiAlN coated carbide inserts was investigated using response surface methodology (RSM) for turning Ti-6Al-4V. The effects of process parameters such as speed (v), feed (f), depth of cut (d) and back rake angle (γ _y ) on F _z and R _a were investigated. The experimental plan used for four factors and three levels was designed based on face centered, central composite design (CCD). The experimental results indicated that F _z increased with the increase in d, f and decreased with the increase in v and γ _y , whereas R _a decreased with the increase in v and γ _y , and increased with d and v. The goodness of fit of the regression equations and model fits (R ²) for F _z and R _a were found to be 0.968 and 0.970, which demonstrated that it was an effective model. A confirmation test was also conducted in order to verify the correctness of the model.