This paper describes design and development of novel lubricant free transmission system for manual bone drilling machine. In order to design the transmission system, applied forces and torques on the gears has to be achieved. In this regard, bone drilling forces and torques were detected, preforming experimental tests of the drilling operation by CNC milling machine. At this point, various drill diameters and machining parameters were considered. After achieving the bone drilling forces, they were utilized for gears design process. The design process including gear geometry, material and detailed design analysis were done according to German norm VDI 2736 - Part 3. In this context, the mating worm gears materials were selected out of stainless steel 316 and Polyether Ether Ketone (PEEK), which can reduce weight, noise, moment of inertia, and necessity of lubrication, etc. In order to evaluate the gears performance, numerically and experimentally were performed. The static stress and deflection of the PEEK gear tooth were investigated numerically by finite element analysis. According to the numerical results, each tooth force carrying capacity (until yield stress) were estimated until 302 N. Surface temperature and wear rate for two types of PEEK gears were examined, experimentally, while applying two resistance torque values, 0.75 and 0.5 Nm, to the manufactured transmission system. The selected torques were three and five times bigger than drilling torque values, enabling us to simulate the bone drilling operation considering unexpected loaded in the extreme case, misuse, emergence situation, and degradation. The maximum temperatures of the tooth contour of the transmission system raised to 127 °C. According to the results, the maximum achieved PEEK gear life was 200 minutes for the Natural PEEK polymer at the 0.5 Nm torque.
Smart Bone Drilling Machine
