Which mechanic is not familiar with this: "This screw should be tightened to 40 Nm."

This kind of specification is to ensure that one gets a reliably fastened joint which does not loosen unintentionally due to incidental vibrations or similar environmental factors. All that counts is achieving the right tension in the screw connection, measured in kilonewtons, by applying the correct torque, measured in newton-metres.

Because it is difficult to measure this tension, one uses the torque. The friction coefficient between the thread and the head of the fastener on the material plays a crucial role in this calculation.

Friction tables

To give you an indication of these friction values, Jeveka includes handy technical information tables on the downloads page. The friction value depends on factors such as the screw material, any coating or lubricant on the screw, and the material being fastened. All of these factors play a major role in this calculation. Keeping these in mind, one can get a reasonable idea of the required torque.

Measurements at your request

Jeveka now has a friction test machine which makes it possible to determine the exact coefficient of friction between the screw and the material of your object. At your request, we can carry out measurements and provide the results in a report. This machine is suitable for the measurement of fasteners from M3 to M16, so most fastener dimensions will be covered.

If you are interested or have any questions, please contact your representative or us.