ABSTRACT
To avoid fastener loosening, Junker recommended that joints be designed such that no relative movement occurs between the contact surfaces or the thread flanks. This requires that a sufficient residual damping force remain after scatter of preload and embedding of contacting components are taken into consideration. The residual clamp load should never fall short of the value equal to the transverse load divided by the friction coefficient. Unfortunately, there are cases when these requirements can be met only if uneconomically overdimensioned fasteners are used. Hence, relative movements cannot always be excluded using this design guideline. In such cases, it was recommended that fasteners with locking elements be used.
