Sooner or later bolts will move, with Nord-Lock washers the movement itself prevents rotation

When using friction locking washers or similar, the preload in the bolt will decrease as soon as rotation occurs, thereby making it even easier for additional rotation. But when using a Nord-Lock wedge locking washer, the preload in the bolt will increase as soon as rotation occurs, thereby prohibiting any further rotation. The graph above illustrates the difference between Nord-Lock washers and other solutions.