Temperature and surface quality investigation in orthogonal machining of cortical bone using response surface method and sensitivity analysis

The cutting temperature and surface quality of machined bone are two significant factors influencing bone machining during orthopedic surgeries such as fracture repair, joint replacement, and dental procedures. An increase in process temperature beyond a certain threshold can lead to thermal necrosis (cell death) and, consequently, tissue damage. Conversely, inadequate surface quality can result in asymmetric bone penetration into the prosthetic joint, leading to loosening of the implant. Orthogonal cutting is utilized as a foundational method for other machining processes in this study. The estimation of temperature performance and surface quality in the orthogonal machining of bone is derived based on tool linear velocity, cutting depth, and rake angle. Furthermore, the optimization of process responses and the interactions affecting them are examined. To quantitatively assess the impact of the results, the Sobol sensitivity analysis method is employed. The findings indicate that the minimum optimal temperature occurs at a tool speed of 140 mm/s, a rake angle of 9.7 degrees, and a cutting depth of 0.1 mm, with cutting aligned to the bone structure yielding a minimum temperature of 17.9 degrees Celsius. The minimum optimal surface roughness is achieved at a tool speed of 275 mm/s, a rake angle of 9.6 degrees, and a cutting depth of 0.1 mm, also aligned with the bone structure, resulting in a surface roughness of 1.07 micrometers. The obtained results can be applied in the investigation and analysis of other machining processes in orthopedics (such as drilling and milling).