What effect will Nord-Lock washers have on my surfaces?
Will Nord-Lock wedge-locking system damage the surface in my application?
Nord-Lock washers are specially designed to create impression marks without scoring the mating surface. The impression marks are important since they prove that the serrations grip correctly into the mating surface. In bolted assemblies rotation always takes place where the friction is lowest. Provided that sufficient impression marks are created any tendency to rotate will occur between the cams of the washers. Consequently, any rotation is prevented by the wedge effect of the cams.
When a joint secured by Nord-Lock washers is tightened, rotation always takes place between the upper washer and the bolt head or the nut. The serrations are simply pressed down into the material, no scoring of the mating surface occurs. The bolt head/nut is hard enough to withstand the minor scoring that it is exposed to. During untightening rotation takes place between the cams of the Nord-Lock washers. Therefore there is no risk of damaging the surface in the application. The impression marks slightly increase the compressive stresses in the surface, but they will not score the material or damage it.