Comprehensive machinability assessment of Ti–6Al–4V for orthopaedic implant manufacturing

The machinability of Ti–6Al–4V remains a critical challenge in precision biomedical manufacturing, particularly for orthopaedic implants, where dimensional accuracy, surface integrity and energy efficiency are essential. In this study, systematic turning experiments were conducted at three cutting speeds (60, 80 and 100 m/min) and five machining durations (30–150 s), with depth of cut and feed rate held at 0.5 mm and 0.1 mm/rev, respectively. Tool wear was monitored by measuring crater and flank degradation, both of which increased progressively with machining time, reflecting cumulative thermal and mechanical stresses at the tool–chip interface. Chip thickness and width increased by approximately 6.55% with higher speeds and up to 23.95% with longer durations, while total cutting energy rose by nearly 40% across the tested speed range. Energy consumption per unit time increased by 86.32% with extended tool–workpiece engagement. Surface roughness exhibited a nonlinear response, initially rising by around 8% at cutting speeds of 60–80 m/min, then decreasing by 12% at the highest speed, reflecting asperity removal and smoother chip flow. In contrast, microhardness consistently decreased by 6%–10% as cutting speed increased across the selected machining duration ranges, highlighting the dominant influence of thermal softening over mechanical strain hardening. These findings establish clear interdependencies among mechanical responses and energy efficiency, offering valuable guidance for optimising process parameters in the manufacture of orthopaedic implants. Overall, the study advances sustainable and precise machining strategies for titanium alloys in orthopaedic applications.