Loosen and re-tighten strategy

This strategy checks the residual torque on the joint. It uses a loosen-and-tighten method to identify the residual point on the torque-versus-time trace.

Parameter	Description
Inspection Name	Name of the inspection.
Cycle start	Torque value from which the test operation starts. The Cycle start must be ≥ smartHEAD Min load value. If Cycle start = 0, its value is automatically set to the smartHEAD Min load value.
Minimum torque	Lower torque limit value.
Maximum torque	Upper torque limit value.
Change screw	If the torque applied reaches this limit, the message Change screw is shown on the wrench display. The Change screw must be ≥ Maximum torque.
Target torque	Torque target value.
Torque tolerance	Torque tolerance that defines the maximum torque and the minimum torque according to the Target torque previously specified. Value is expressed in percentage (%).
Control mode	Method to define the torque limits from the following options: Min/Max: the torque lower and upper limits are the values entered for the parameters Minimum torque and Maximum torque. Target/Tolerance: the torque lower and upper limits are calculated according to the values of the parameters Target torque and Torque tolerance.
Target angle	Loosening target angle
Torque correction coefficient	When extensions are used, the wrench measurement must be compensated to show a more accurate torque value. To calculate the correction coefficient, please refer to How to calculate the Torque Correction Coefficient. When extensions are not used, Torque correction coefficient = 1.
Angle correction coefficient	When extensions cause additional wrench bending, the wrench angle measurement must be compensated to show a more accurate angle value. To calculate the correction value, please refer to How to Calculate the Angle Correction. When extensions are not used, Angle correction coefficient = 0.
Number of sample	Number of tests to run inside the inspection. Maximum value: 1000. If Number of sample = 0, the number of tests is infinite. If Number of sample > 1, batch result OK only if all tests are OK.

The residual torque is the torque measured at the end of the re-tightening operation, at the target angle. The target angle is usually set to a few degrees. If the angle is set too high, the torque during the loosening phase may drop below the cycle start value. In that case, the angle measurement will stop, and the test cannot continue.


Loosening	Re-tightening