Can I use other washers with Nord-Lock washer?
Can I put another washer under a Nord-Lock washer?
It is recommendable to use Nord-Lock washers directly on the mating surface. An additional washer can only be used with Nord-Lock if the underlying washer is locked in place. Nord-Lock washers only lock and prevent rotation in the adjoining surfaces. If the underlying washer is not firmly locked in place, rotation may still occur (see Fig 3), resulting in considerable loss of clamp load. Insufficient clamp load, in turn, can lead to fatigue failures. Also note that extra washers mean more settlements, which results in increased loss of clamp load.
In applications where the mating surface is too hard for Nord-Lock washers to obtain the necessary impression marks, a softer underlying washer can be used to create these marks. However, it is crucial to make it impossible for the underlying washer to rotate. This can be achieved using a washer that is large enough to be secured with two bolts, for example.