We often hear this question. More importantly, when discussing torque measurement, we see a lot of misinformation about breakaway torque.
We've been making torque tools for nearly 80 years. We don't make other types of wrenches. We only make torque application tools. Torque application is not a sideline with us. It is our only and total focus.
What is breakaway torque?
Once torque has been applied to a joint, an audit function measures exactly how tight that fastener was torqued.
After being tightened, and torque is applied, there is a point when the fastener begins to move again. That point of movement is "breakaway torque."
It starts with selecting the appropriate torque wrench.
When auditing previously tightened fasteners, using the appropriate torque wrench is imperative. You'll want to use the most accurate wrench you can find.
In an ideal world, you would use a wrench with torque and angle measurement capabilities. Sturtevant Richmont digital torque and angle wrenches come equipped with a radio and there are models without an embedded radio.
Digital torque wrenches with a radio are designed to communicate with the Global 400 and Global 400mp torque controllers. To find more information about those wrenches look for our 1250 Exacta Series digital torque and angle wrenches.
We also make suitable audit tools without a radio. Those wrenches are the DTC digital torque and angle wrenches.
Once you have the appropriate wrench selected, the process is the next point of focus.
Mode of Operation is important.
Just as there are different modes of operation for different tools in torque application, there is a specific mode of operation for establishing the value of breakaway torque. That mode of operation is called "Residual Mode." It is called residual mode because breakaway torque is often referred to as residual torque.
So far, everything has been straight forward. That means this is where it gets messy.
In which direction should you apply force to create the movement needed to establish breakaway torque?
Despite the laws of physics and application of common sense, some still come to the wrong conclusion.
For this example, consider a fastener that is turned clockwise to tighten and is turned counterclockwise to loosen.
Which direction should the fastener be turned to establish "breakaway torque"? Clockwise!
Why clockwise? (The appropriate direction for breakaway torque is always additional tightening of the fastener. In this example, clockwise tightens the fastener.
Remember that break away torque is that moment in time when the previously torqued fastener begins to move again. Once that movement happens, it cannot be created or captured again.
If you move the fastener counter-clockwise (loosen it) you've just destroyed the joint that someone worked so hard to create.
Given reaction times, we've seen too many cases where someone trying to establish breakaway torque simply loosens the fastener to the point where the joint is no longer in the condition it was when the fastener was tightened.
That is a problem. You were just trying to solve for the established torque value of a previously tightened fastener, and now you are creating the problem of a joint that is no longer in the condition it once was.
If you tighten the fastener, catching the moment of movement is easier. More importantly, you will get a more accurate breakaway torque reading.
Most importantly, in your audit to validate accuracy, you won't destroy the joint that you are auditing.