How do you Calculate Static Torque?
Tightening method
Use a torque wrench to gradually increase the torque by applying steady force. When the nut or bolt begins to rotate slightly, the instantaneous torque value is the largest due to the need to overcome friction. After continued rotation, the torque value drops back to a short-term stable state. The torque value at this time is the inspection torque.
This method is simple to operate. But it requires skilled technicians. There is a possibility of secondary tightening. It is difficult to determine the start time of the bolt. There are subjective factors, and the test torque is generally too large.
Marking method
Before the test, mark the head of the bolt or nut and the connected body to clarify the original position. Loosen the bolt or nut a little. Then tighten it to the original position with a torque wrench. Align the marked position, and multiply the maximum torque value measured at this time by 0.9 – 1.1 to get the inspection torque value.
This method does not require a high technical level. The operation is cumbersome. It is not suitable for fasteners with anti-loosening function. But the test results are more accurate than the tightening method.
Loosening method
Use a torque wrench to slowly apply torque to the bolt or nut to loosen it. And read the instantaneous torque value when it starts to rotate. And multiply by 1.1 – 1.2, the result is the test torque value.
This method is simple to operate. But it requires experienced personnel to operate. The tested torque value is smaller than the actual torque value.
When testing static torque, you should also pay attention to choosing the right testing tool.
Static torque wrenches are generally divided into dial-type and digital display-type. The dial type is cheap, but the accuracy is low. The digital display type with a sensor can set the angle. The accuracy is high, but the price is also high.
How to Choose the Right Static Torque Transducer?
- Clearly define the measurement range
- Consider the accuracy requirements
- Evaluate environmental adaptability
- Pay attention to the output signal type
