Direction-dependent analysis of force and torque in conventional and ultrasonically-assisted drilling ofcortical bone

Bone drilling is a common surgical procedure in orthopaedic, neuro, and dental surgeries for internal xation. Estimation and control of the bone drilling force and torque are critical in preventing drill breakthrough, excessive heat generation and unnecessary mechanical damage to the bone. This paper illustrates experimental measurements, and a comparison of the drilling thrust force and torque in Conventional Drilling (CD) and Ultrasonically-Assisted Drilling (UAD), in two directions; along the longitudinal axis of the bone and normal to it (radial direction). The objective of this research is to nd the eect of drill size and ultrasonic vibration superimposed on drill movement, on the thrust force and torque. The eect of drill speed on force was investigated in the described directions, followed by a series of experiments, to explore the in uence of drill size and penetration direction on the level of force and torque. The drilling force and torque were found to be strongly dependent on the drilling direction. Experimental results reveal that when drilling in a specic direction, lower drilling force and torque are found in UAD compared to CD.