Tightening technique

The tightening technique determines how much the tightening torque varies. Thus, if a minimum pretensioning force is required, a maximum pretensioning force must also be expected, which in turn determines the necessary strength of the bolt.

The following options are available:

• with a simple tightening spindle which has been set by the retightening torque (large scatter)

• with a torque wrench or precision spindle adjusted by means of dynamic torque measurement or elongation measurement of the bolt, or by a pneumatic impact wrench (medium scatter)

• with angle control within the plastic range or by means of computer-controlled yield-point monitoring (no scatter)