What are the improvement measures for errors caused by internal stress in precision parts processing

In the field of precision parts processing, the so-called internal stress refers to the stress that remains inside the workpiece after the external load is removed. Internal stress is produced during the processing of a workpiece due to uneven volume changes in its internal macroscopic or microscopic structure.

Parts with internal stress are in an unstable relative equilibrium state, which can maintain temporary stability of shape accuracy. But its internal organization has a strong tendency to restore to a stable state without internal stress. Once external conditions change, such as changes in environmental temperature, continued cutting, or being impacted, the temporary balance of internal stress will be disrupted and redistributed, causing corresponding deformation of the parts, thereby damaging the original accuracy.

In order to reduce or eliminate the impact of internal stress on the machining accuracy of precision parts in machining, when designing the structure of parts, it is necessary to simplify the structure as much as possible and consider uniform wall thickness to reduce the internal stress generated in the manufacturing of casting and forging blanks. During cutting, rough and precision machining should be separated in different processes, with a certain interval after rough machining to redistribute the internal stress and reduce the impact on precision machining.