Force-thermal behaviors and process optimization of ultrasonic vibration-assisted bone drilling for minimally invasive orthopedic surgery

Bone drilling is a critical procedure in orthopedic surgery, where the resulting surface quality directly affects postoperative bone healing, implant stability, and long-term biomechanical performance. Due to the pronounced anisotropy, high thermal sensitivity, and porous microstructure of cortical bone, conventional drilling (CD) frequently induces elevated forces and temperatures, which may trigger microcrack propagation, tissue carbonization, and thermal necrosis. To address these limitations, this study develops a high-precision drilling platform to evaluate drilling force, temperature field, and hole-wall morphology, and systematically compares the performance of CD with ultrasonic vibration-assisted drilling (UVAD). UVAD exhibits a distinct low-damage processing window at 1500-2000 rpm, 20-40 mm·min -1 , and a vibration amplitude of approximately 2.0 μm. Under the optimized condition of 1800 rpm, 30 mm·min -1 , and 1.8 μm, UVAD achieves a maximum drilling force of 25.1 N, a maximum average temperature of 45.3 °C, and a surface roughness of 0.63 μm, corresponding to reductions of 30.8%, 27.6%, and 47.7%, respectively, relative to CD. The high-frequency axial micro-vibration creates a periodic contact-separation interaction at the tool-bone interface, thereby weakening force-thermal-surface coupling and mitigating drilling-induced damage. These results elucidate the intrinsic low-damage mechanism of UVAD and provide quantitative guidance for minimally invasive orthopedic surgery. • Develops a multi-field coupling framework for ultrasonic bone drilling. • Enables high-precision characterization of force, temperature, and surface integrity. • Confirms the effectiveness of ultrasonic vibration in reducing force-thermal loads. • Determines the optimal parameters for ultrasonic bone drilling. • Proposes a low-damage drilling strategy for minimally invasive orthopedic surgery.