Finding the optimal drill bit material and proper drilling condition for utilization in the programming of robot-assisted drilling of bone

Most of the orthopedic surgeries require bone drilling, and accurate control of optimal values of parameters influencing the process of bone drilling in robot-assisted orthopedic surgery is important. Bone drilling process including three materials and three diameters of the drill bit, and three drilling depths, four cooling modes, and ten drilling angles were simulated on the tibia and femur bones using the finite element method (FEM). After ensuring the correctness of FEM simulation results using comparison with experimental data, the impact of the above variables on the changes of three parameters of maximum temperature, thrust force and torque, and temperature durability was assessed. The increase of drill bit diameter and drilling depth, and decrease in the drilling angels led to an increase in the aforementioned parameters, and bone drilling conditions become less favorable. The drill bit with stainless steel material and with gas coolants (especially CO2 coolant) resulted in more optimal bone drilling conditions even in higher drill bit diameter and depth of drilling. The equations between temperature, thrust force, and torque with drilling angles in various cooling modes have been calculated for the programming of drilling robots during orthopedic surgeries to obtain the optimal accurate angle during surgeries. (C) 2020 CIRP.