TORQUE: The False Indicator of Your Clamp Performance

julio 14, 2022

1. The working of a Worm Drive Hose clamp-

When the torque is applied the threads on the screw engaged in the strip pull the strip against the housing thereby producing an effective clamp joint. In this so-called small action, there are a series of complex events which takes place. The input torque applied is first converted to effective tensile force which is stored in the form of strain energy & second is the conversion to heat energy due to frictional losses of mating components. This strain energy is the potential energy stored in the band due to its elastic deformation, it is the same energy that is stored in the case of a stretched bow. And it is this strain energy that produces the useful clamping force by causing the micro elongation of the band which can be calculated from the area under the curve of the Force Vs Displacement graph. This effective clamping force generated is termed Band Tension which in turn makes up for an effective clamping joint. We will further discuss the concept of Band tension & losses in subsequent points.

2. The Devil is here-

The undesirable heat losses due to friction encountered in our story are as follows-

Friction between the inside of the clamp strip & clamped object
Frictional losses due to screw & band interaction
Screw collar friction losses
Losses due to manufacturing inaccuracies
Friction between band & housing inner surface

Attempts should be made by the clamping experts to identify the potential sources of losses & minimize them wisely to improve the performance of the hose clamp. Visit our wide range of high-performance clamping solutions provided by jolly clamps here.

3. The Concept of Band Tension-

Band Tension is the amount of tension generated in the band after the introduction of application torque as a result of strain energy. Clamping experts have expressed this Band tension in terms of Radial load, Polar force & Belt tension, etc. Contact our clamping experts at Jolly Clamps for more details on how we can use these tests to help you with a leak free joints with our advanced in-house testing facility.

4. Torque: The False Indicator-

Torque is an input applied to the clamp to generate the effective clamping force. Till days clamp manufacturers & end users have been using the maximum torque sustained by the clamp as means to measure the performance of the clamp. But that’s not correct! The maximum Torque value does not guarantee a leak-proof joint as the applied torque is not always successfully converted to an effective clamping force. Numerous losses as stated above in the clamp assembly & joint does not permit complete conversion of Torque to Band Tension. While measuring the ultimate breaking torque of the clamp the torque wrench displays the torque sustained by the clamp & not the number of losses it has witnessed to reach that torque displayed hence, Torque is the false indicator for measuring the hose clamps performance. Instead, the two methods stated above should be used in measuring the clamping efficiency & enjoying a leak-proof joint.
Tech Tip-

The best clamp is the one with lowest Idling torque & Highest Breaking Torque.