Machining Constraint Analysis of CNC Turning in the Manufacturing Process of Titanium Ti-6Al-4V ELI Bone Screw Implants

Abstract

General Background Orthopedic surgical fixation relies on implants manufactured from materials combining high strength-to-weight ratios with superior biological compatibility. Specific Background The automated fabrication of these cylindrical components using Ti-6Al-4V ELI alloys presents severe manufacturing difficulties due to the material's low thermal conductivity and reactive chemical properties. Knowledge Gap While studies frequently address theoretical cutting forces, comprehensive strategies integrating continuous chip management, accelerated cutting tool degradation, and structural deflection within active industrial production environments remain underexplored. Aims This study investigates specific mechanical issues encountered during the automated shaping of medical fixations and implements integrated corrective strategies to optimize production stability. Results Qualitative observation and field inspections identified continuous chip nesting that scratches surfaces, rapid tool degradation due to concentrated thermal accumulation, and dimensional tapering exceeding the ±0.04 mm tolerance caused by radial deflection. Applying focused, high-pressure emulsion fluid broke the chips into manageable segments and dissipated accumulated thermal energy, significantly reducing tool degradation. Furthermore, structurally securing the workpiece utilizing a tailstock support system effectively countered radial deflection, reducing dimensional deviation to a compliant +0.018 mm. Novelty The research establishes a direct, field-tested integration of fluid dynamics optimization and physical structural reinforcement for precision medical component manufacturing. Implications Combining targeted fluid applications with rigid structural support eliminates surface defects, preserves cutting tool integrity, and strictly conforms to stringent medical dimensional tolerances. Highlights: Low thermal conductivity concentrates cutting heat, accelerating tool degradation during automated shaping. Targeted emulsion fluid application effectively manages thermal accumulation and fragments continuous chips, eliminating surface scratches. Implementing structural workpiece supports counters radial deflection, reducing dimensional deviations well within the ±0.04 mm quality threshold. Keywords: Implant Fabrication, Cutting Tool Degradation, Radial Deflection, Coolant Optimization, Surface Roughness