In the procession of aviation parts, medical robots and semiconductor testing equipment, material accuracy is required to reach the limit level of verticality, parallelism and flatness error ≤ 0.005mm. The performance stability of such high-precision products directly depends on the degree of elimination of residual stress inside the material. As two core surface finishing processes, artificial aging treatment and cryogenic treatment show significant differences in achieving this goal:
1.Residual stress control
Deep cryogenic treatment:
By cooling the material to -196°C (liquid nitrogen temperature), the internal microstructure of the material is homogenized and the residual stress is significantly reduced. This reduces the risk of deformation caused by stress release during subsequent processing or use, which is crucial to maintaining high-precision geometric tolerances.
artificial ageing treatment:
By heating (such as 150-200°C) and heat preservation, strengthening phases are precipitated to improve strength, but the processing residual stress may not be completely eliminated, and new thermal stress may even be introduced, resulting in subsequent dimensional instability.
2. Material stability and microstructure
Deep cryogenic treatment:
Refine the grains and stabilize the microstructure, reduce the dimensional changes caused by temperature fluctuations or time, and improve long-term dimensional stability.
artificial ageing treatment:
Mainly relies on precipitation phase strengthening. If the aging parameters (temperature, time) are not properly controlled, it may lead to uneven distribution of precipitation phases, affect the homogeneity of the material, and then cause local deformation.
3. Influence of mechanical properties
Deep cryogenic treatment:
Improve the hardness and wear resistance of the material while maintaining toughness, which helps to reduce tool wear during finishing and improve surface quality.
artificial ageing treatment:
Significantly improve strength and hardness, but too high hardness may increase cutting difficulty, resulting in shortened tool life or surface microcracks, which indirectly affects accuracy.
4. Processing process optimization
Deep cryogenic treatment:
Usually carried out after roughing and before finishing to eliminate the pre-processing stress and ensure uniform finishing allowance; it can also be used to further stabilize the size after final processing.
artificial ageing treatment:
It is usually used as a routine process after solution treatment. If it is performed before finishing, the final accuracy may be affected due to insufficient elimination of residual stress.
5. Cost and process complexity
Deep cryogenic treatment:
It requires special liquid nitrogen equipment, which is costly and complex in process control, but is suitable for high value-added aviation parts.
artificial ageing treatment:
The equipment is mature and the cost is low, but the accuracy guarantee depends on strict parameter control, and the effect on parts with complex shapes may be limited.
Conclusion：
For ultra-high precision requirements of 0.005mm, cryogenic treatment has more advantages in reducing residual stress and improving dimensional stability, especially for key aluminum structural parts such as aviation, medical and robots. General aging treatment focuses more on strength improvement, and needs to be combined with precision machining technology (such as multiple aging + low temperature processing) or used in conjunction with cryogenic treatment to take into account both strength and accuracy. In practical applications, it is necessary to make a comprehensive selection based on part structure, cost budget and production cycle.
