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ADDITIONAL INFORMATION & FEATURES Section 4
YIELD FUNCTION
YIELD FUNCTION
YIELD FUNCTION
YIELD FUNCTION
YIELD FUNCTION
It is available in Quick Store and Jobs if Advance and Angle features are enabled.
The function relies on measuring torque and angle and calculating the slope of torque
versus angle. The wrench uses the definition of when this slope falls to half its
maximum as the yield. This is just past the true definition of the ‘yield point’ which is
when the joint will not elastically return to its original length.
Before performing yield, first take a trace while performing a good fastening with the
bolt yielding. Then download that graph to Opta Comms and export to Excel. From
that graph you can work out if the joint type is hard, medium or soft. For example, if
the bolt goes into yield at about 30 degrees, then it is suggested that you set the Joint
Type (in measurement setup) to Hard.
When pulling the wrench, you must watch the LEDs as these will tell you when you
have reached the bolt yielding as per the algorithm above. If yield is reached then the
LEDs will flash quickly with the torque and angle status at yield recorded. If yield is
not reached then the LEDS will flash slowly and alternate with 2 Amber LEDs.
Once the fastening is pulled, only the yield torque and angle are recorded so they can
be downloaded to Opta Comms, or Printed out or Viewed.
The Yield Algorithm works as follows:
It starts once the torque has gone above torque threshold
Trace data is stored so have a torque value against angle for each 1°
increment of angle.
A gradient of the torque vs angle graph is calculated. The size of the
chord measuring the gradient is set by the user in terms of the angle
difference (along the x-axis - angle)
Soft
= 24°
Medium
= 16°
Hard
= 12°
The maximum gradient is found and stored.