Verification of friction coefficients of lubricants

Verification of lubricant friction coefficients

In our laboratory we have special equipment for verifying the coefficients of friction of lubricants and pastes used for lubricating bolted joints. The measured results are used in the calculation of tightening torques.

• The equipment and the measurement of friction coefficients in the thread and under the head are carried out in accordance with EN 16047.
• We develop our own lubricants for bolted joints.

Example of friction coefficient waveforms measured in accordance with EN 16047

The graphs show the steady state friction in the thread and under the nut. The horizontal axis represents the theoretical pressure in the thread pth and under the nut pb, which increases during tightening. It can be seen from the curves that the friction does not change with increasing load.
Curve of friction coefficient in the thread as a function of load

LF Booster - assembly paste for bolted joints

Curve of friction coefficient under nut as a function of load

Measured on M33x3,5x300 bolts according to ČSN 131520.2

Need the right tightening torque?

Calculator can be found at: utahovacimoment.tesneni.cz

How does it work?

1. Entering values
2. Optimal tightening torque design
3. Display of the load level of the bolted joint in the assembly state

Tightening torque calculation

The result is the tightening torque MU and a check of the bolt in terms of tensile stress σt [MPa], torsion τk [MPa] and reduced stress for the POWER®torque LF lubricant 450.