In addition to heat treatment, the main methods to improve the hardness of gear reducer shaft components include surface strengthening treatment, coating technology and mechanical processing strengthening process. These methods can significantly improve the surface hardness and wear resistance of key parts without changing the overall performance of the shaft.
1. Surface coating technology
By depositing a high-hardness film on the surface of the shaft, the surface performance is improved:
Diamond-like carbon film (DLC): hardness can reach 1500–3000HV, friction coefficient as low as 0.08–0.1, suitable for high speed, light load or precision transmission shaft.
Physical Vapor Deposition (PVD)/Chemical Vapor Deposition (CVD): can form hard coatings such as TiN and CrN to significantly improve wear resistance, especially suitable for precision gear shafts.
Hard chromium plating: A traditional but effective method, the surface hardness can reach above HV800, but attention must be paid to environmental issues and bonding force control.
2. Mechanical surface strengthening
Use plastic deformation to improve the surface tissue structure and increase hardness and fatigue strength:
Surface rolling strengthening: The rolling tool applies pressure to the shaft surface to refine the grains and generate residual compressive stress. The surface hardness can be increased by 15%-30% and the roughness can be reduced at the same time.
Ultrasonic surface finishing: Combining high-frequency vibration for finishing processing can not only obtain a mirror effect, but also improve the surface density and hardness. It is suitable for long shafts and screw parts.
3. High energy density surface modification technology
No need for overall heating to achieve precise local strengthening:
Laser quenching: The laser beam is used to quickly heat the surface and self-cool, forming a martensite hardened layer with small deformation and high precision, suitable for high-precision spindles.
Ion implantation: Inject high-energy ions into the surface layer to change the material composition and structure, significantly improving the hardness and corrosion resistance without affecting the size of the workpiece. It is mostly used for precision shaft parts.
4. Material replacement and composite strengthening
Without changing the heat treatment process, the hardness can be indirectly increased through material upgrading:
Use 20CrMnTi, 38CrMoAl and other alloy steels, combined with carburizing or nitriding treatment, to achieve "hard exterior and tough interior".
Adopting the "vacuum carburizing + nano-coating" integrated solution, heat treatment deformation is reduced by 60%, and the wear-resistant life is increased by 5 times compared with traditional processes.
