In recent years, the demand for replacing metal gears with carbon fiber reinforced plastic (CFRP) gears has been increasing due to their high specific strength and excellent vibration damping properties. Conventional fabrication methods include molding short fiber-reinforced resin and machining laminated composites. However, a fabrication method to improve the strength of CFRP gears has not been fully established. In this study, a novel fabrication method was developed to improve the strength of CFRP gears. The proposed method reinforces the tooth flanks with carbon fiber fabrics before casting short fiber-reinforced resin into a mold. To evaluate the effectiveness of this approach, the effects of fiber length, fiber content, and the number of fabric layers on the strength of CFRP gears were investigated. The bending strength of gear teeth was evaluated to verify the practicality of this method. The results indicated that strength improvement requires increasing the fiber volume fraction while ensuring uniform fiber dispersion in the resin. Furthermore, it was found that increasing the number of fabric layers while suppressing interfacial delamination between fibers and resin enhances the strength of the tooth flanks. In conclusion, valuable insights were obtained regarding the applicability of this manufacturing technique for producing high-performance CFRP gears.
Mitsubayashi et al. (2026) studied this question.