Premature Torque Loss Detection
The tightening program moves from rundown to tightening when the screw head is snug and the torque increases rapidly. This point is refereed to as the Rundown torque and is defined by reaching the set torque value.
For a correct tightening, it is assumed that the torque increases. If the torque decreases, the following may be assumed:
The socket slips of the screw head while the tool trigger is still pressed. The tool detects rapid decrease in torque and continues to rotate according to its speed setting.
The screw breaks while the tool trigger is still pressed. The tool detects rapid decrease in torque and continues to rotate according to its speed setting.
If a decrease in torque is detected at this stage, proceed with the following:
Save the last torque value before a decrease is detected.
Start a detection timer.
Continue the tightening and measure the torque.
If the torque builds up and reaches the saved level and continues to build according to the tightening program within the set time period, then continue normally with the tightening
If the torque loss continues until the end of the set time period, the tightening is considered NOK.
If the tool detects the torque loss, it continues to spin freely as long as the tool trigger is pressed. The tightening is terminated when the operator releases the trigger and result is reported with detailed NOK reason = premature torque loss detected.
