Optimization of micro tool geometry for ballpoint pen tip production using finite element simulation and orthogonal experiments

Micro-drilling in ballpoint pen tip production faces persistent challenges of tool wear and premature breakage, which limit manufacturing efficiency and dimensional accuracy. In this study, an integrated framework combining finite element simulation (FEM) and orthogonal experimental design was developed to optimize the geometry of micro twist drills. A three-dimensional FEM model was established in Deform‑3D to analyze the effects of apex angle, helix angle, chisel edge length, and chisel edge angle on cutting force and torque. Range analysis of the orthogonal design revealed that chisel edge length and apex angle were the most influential parameters. The optimal configuration (b = 0.05 mm, 2Φ = 135°, Ψ = 76.5°, β = 3°) reduced average torque by 22.2% and extended tool life by 43.9% compared with the original design, while maintaining hole dimensional accuracy within ± 0.01 mm. These results confirm FEM as a reliable predictive tool and demonstrate that the proposed FEM-orthogonal framework provides a structured and cost-effective strategy for micro-tool geometry optimization, with direct industrial applicability to precision manufacturing of ballpoint pen tips.