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Methods for Calculating Appropriate Tightening Torque

When you are trying to determine the tightening torque you need for a fastener, there are a couple ways you will want to go about it. It may seem like a fairly easy answer, but that is not always the case.

Use a Torque Calculator

Using a torque calculator to determine the approximate tightening torque is a good place to start. This calculator will request information such as the coefficient of friction, the bolt strength and diameter. A torque calculator is a good way to get started and get an approximate tightening torque, however, it will not be exact in all situations. This is why after using a calculator, it is a good idea to perform some joint testing to verify your results.

Test Your Torque

Once you arrive at the proper torque requirement, you may want to test your torque values to verify the accuracy of your assembly tools. This is important because it helps you ensure the safety, reliability and quality of your project.

You will need a calibrated hand torque wrench to verify the tightening torque of your fasteners. You can select from the First Movement Test, the Loosening Test and the Marking Test as an indication of the applied torque:

  1. The First Movement Test will involve applying force to your torque wrench after the fastener has been tightened. You will do this until the first movement of the fastener is noted.
  2. The Loosening Test requires that you turn the fastener in the opposite direction to loosen it. You will record the torque when the fastener first breaks loose.
  3. For the Marking Test, you will need to mark the fastener and continue to mark onto the surface being clamped. Then you will loosen and retighten until the marks match up.

It is important to use the proper torque on your project to ensure safe, reliable joints. To learn more about torque and methods for measuring it, contact Bossard at ProvenProductivity@bossard.com.

Methods for Calculating Appropriate Tightening Torque by
March 17, 2017

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