ALL-METAL SELF-LOCKING HEXAGONAL DOUBLE SLOTTED NUT WITH MOBILE WASHER– MÉTRIQUE METRICAL
The principle of self-locking nut ERM is to compress the flank of the thread of the male element on two sectors located in different planes and offset by 180 °.
This principle is obtained by making two calibrated slots in the upper turret of the nut which are then crushed under a specific load to obtain a permanent deformation of the two slots (elastoplastic deformation).
During the assembly, the deformed slots in the upper turret of the ERM nut are pushed by the thread of the male element. This thrust generates pressure on the side of the flank of the thread of the male element on two sectors creating a constant locking torque (called self-locking). This self-locking torque is independent of the prevailling torque applied when tightening the ERM nut.
The ERM nut has also a mobile conical washer. It flattens during assembly when the male element is tensioned under the effect of tightening torque. In the life cycle of an assembly using an ERM nut, phenomena can lead to a release of the initial tension of the male element. The conical washer will restore the energy stored during compression and maintain part of the tension in the assembly.
ERM nuts are recommended for all common or safe assemblies with risks of loss of initial tension. These voltage losses are generated by settlements, creeps or vibratory phenomena.
Examples:
– several stacked pieces
– assemblies incorporating racks or teeth
– assemblies of parts consisting of low-hardness metals or flexible materials
– assemblies of painted parts
– electrical connection assemblies, etc
