Meaning
Quality control procedure used to verify that fasteners maintain their specified clamping force after a period of time or environmental testing. torque retention audit involves measuring the residual torque on a bolt or screw to check for loosening caused by vibration or thermal cycles. It is a standard part of the validation process for electronic enclosures and mechanical assemblies.
Verification Procedure
Inspectors use a calibrated torque wrench to measure the breakaway torque in the tightening direction. A torque retention audit typically follows a thermal shock or random vibration test to simulate the lifecycle of the product. The results are compared against the initial installation torque to determine the percentage of loss.
Data Integrity
Accurate records of the initial and final torque values provide a clear picture of the reliability of the joint. Engineers use the data from a torque retention audit to identify issues with material selection or fastener design. If the retention rate is too low, the assembly may require the addition of thread locking compounds or different washer types.
This data is often included in the final qualification report for the assembly.
Corrective Action
Modification of the tightening sequence or the torque specification occurs if the audit fails to meet the pass criteria.
