Bone Abrasive Machining: Influence of Tool Geometry and Cortical Bone Anisotropic Structure on Crack Propagation

The abrasive machining of cortical tissue is used in many arthroplasties and craniofacial surgery procedures. However, this method requires further research due to the processes' complexity and the tissue's composite structure. Therefore, studies were carried out to assess the impact of grid geometry and the anisotropic structure of bone tissue on the cutting process and crack propagation. The analysis was performed based on an orthogonal cutting in three directions. The grain shape has been simplified, and the cutting forces, crack path and surface quality were monitored. The results indicate that a depth of cut at 100-25 mu m allows the most accurate cutting control. A transverse cutting direction results in the greatest surface irregularity: Iz = 17.7%, Vvc = 3.29 mL/m(2) and d(f) = 5.22 mu m and generates the most uncontrolled cracks. Maximum fracture force values of FF > 80 N were generated for d = 175 mu m. For d < 5 mu m, no cracks or only slight penetration occurs. A positive gamma provides greater repeatability and crack control. Negative gamma generates penetrating cracks and uncontrolled material damage. The individual types of cracks have a characteristic course of changes in F-x. The clearance angle did not affect the crack propagation.