Object: To show the importance to use the recommended tightening torque.
Recommended tightening toruques on screw clamping are researched from 7 cutting tool catalogues.
Screw clamping is the fixation type which directly fix the indexable insert to the body by the screw.
Thus, it is important to controll the tightening torque.
In the research results, screw axial forces are also shown.
From these, you can understand that the effect of tightening torques to screw axial forces are too large.

\( T = k \cdot d \cdot F \)

\( T \): Tightening torque
\( k \): Torque factor（0.1-0.4； 0.15-0.2 is used generally）
\( d \): Diameter of screw part
\( F \): Screw axial force

When the tightening torque is lower, there is the possibility that the screw does not fix the indexable insert.
When the tightening torque is higher, there is the possibility that the screw life bocome short.
It is important that same screw size do not have same tightening torque.
Thus, it is tha best to check and use the recommended tightening torque from the cutting tool catalogue.

Most of screws on screw clamping are Hexalobular internal.
There are some wrenches to measure tightening torques in Hexalobular internal.
You can use them.