Numerical and experimental investigation of cutting force in rotary broaching process of Ti6Al4V using Johnson–Cook constitutive model

Machining titanium alloys such as Ti6Al4V is challenging due to their low thermal conductivity, high strength, and tendency for tool adhesion. Understanding how process parameters influence cutting forces is essential for improving tool life, surface quality, and process stability in these difficult-to-machine materials. This study investigates the rotary broaching of Ti6Al4V alloy to evaluate the effect of tool cutting feed on cutting forces and material deformation. The objective is to quantify the relationship between cutting feed, axial force, and equivalent plastic strain (PEEQ) during the broaching process. A combined experimental and numerical approach was employed, involving axial force measurements using a Kistler 9257BA dynamometer and finite element simulations based on the Johnson–Cook constitutive model. Cutting feeds of 5, 25, 45, 65, and 85 mm/min were tested to assess their influence on axial force behavior and plastic strain distribution. Results showed that increasing the cutting feed raised the mean axial force from approximately 2.0 kN to 2.8 kN but reduced the force fluctuations, indicating improved process stability. This reduction in fluctuation is primarily attributed to the shorter tool–workpiece contact time at higher feeds, which leads to more uniform material removal and steadier cutting action. Additionally, PEEQ values decreased with increasing feed, reflecting less extensive plastic deformation and enhanced process consistency. These findings highlight that optimizing cutting feed is crucial for achieving stable, efficient, and reliable rotary broaching of Ti6Al4V alloy.