# Residual Torque / Angle

This strategy evaluates the residual torque on a joint, looking for the residual point of the Torque/Angle trace.

Parameter | Description
--- | ---
Inspection Name | Name of the inspection.
Cycle start | Torque value from which the test operation starts. The Cycle start must be ≤ Final angle monitoring torque value, and 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.
Maximum torque | Upper torque limit.
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 torqueMaximum torque.
Target torque | Torque target value.
Torque tolerance | Tolerance that defines the maximum torque and the minimum torque according to the Target torque previously specified. Value is expressed in percentage (%).
Final angle monitoring torque | Torque value from which the angle measurement starts (usually set to 50% of the Target torque). If Final angle monitoring torque = 0, its value is automatically set Cycle start value.
Measuring unit | Measurement unit set for the joint linked to the inspection.
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.
Breakaway angle threshold | Maximum angle value (measured from the Final angle monitoring torque) for the residual torque.
Residual angle threshold | Maximum angle value (measured from the Final angle monitoring torque) for the residual torque when the residual torque is lower than the breakaway point.
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.
Ratchet time | Starts when the torque goes below the Cycle start without reaching the 3rd percentage value. This allows the operator to release the torque for a while and recharge during the tightening operation. Default value: 5 sec. Minimum value: 0.1 sec. Maximum value: 30 sec.

Torque vs. Angle with Breakaway = Residual

A | Cycle start | B | Minimum torque
C | Maximum torque | D | Breakaway = Residual

Torque vs. Angle with Breakaway different from Residual

A | Cycle start | B | Minimum torque
C | Maximum torque | D | Breakaway
E | Residual |  |

Define the torque limits to get an OK result.

The Final angle monitoring torque, which must be greater than the Cycle start, defines the point from which the device algorithm starts analyzing the torque/angle trace. This is useful to filter all the noise that may occur at low torque value, and that could be detected as a false residual point.

Torque result:

- If the residual point is detected, the result is associated with the residual point; the test is OK if the residual falls within the limits.

- If the residual is not detected or the torque goes over the maximum torque, the torque result is the maximum value. Therefore, if the maximum value falls within the limits, the torque result is still OK, but the overall result is marked as Not OK.

- If the torque goes over the Change screw value, the residual is no longer detected and the torque result is the maximum torque.

In the configuration of the Residual torque/angle strategy, there are two advanced parameters:

- Breakaway angle threshold: it specifies the maximum angle for the residual torque (measured from the Final Angle Monitoring Torque).

- Residual angle threshold: it specifies the maximum angle for the residual torque (measured from the Final Angle Monitoring Torque) when the residual torque is lower than the breakaway point.

  If the residual point precedes the Residual angle threshold, the residual torque is detected. This is the normal condition for a residual torque test.

  If the residual point is over the Residual angle threshold, the breakaway point is the result of the test. In this case, the Residual angle threshold should be increased to detect the proper residual point.

  If the breakaway point is over the Breakaway angle threshold, the residual point is not detected even if the residual point precedes the Residual angle threshold.

During the test operation, LEDs, buzzer and vibration are activated as follows:

- LED:

  - White LED: activated when the Cycle start is reached.

- Buzzer:

  - The beep starts when the torque goes over the Cycle start value; the signal increases when the residual torque is detected / the tightening process has been completed.

- Vibration:

  - Starts when the residual torque is detected.

At the end of the test operation, LEDs, buzzer and vibration are activated as follows:

- LEDs:

  - Green LEDs: torque result within the minimum and maximum limits.

  - Red LEDs: torque is outside the minimum and maximum limits range.

- Buzzer

  - Two beeps indicate the end of the operation; if the final result is in the red area, the signal in continuous.
    To stop the buzzer, start a new tightening operation or press a button on the tool controller.

- Vibration:

  - Stays active until the torque applied is released.

In this Section

- Residual Point Detection Algorithm
- Three points residual