| In order to assure the unique locking function of the BOPA-LOCK washers, the
hardness of the mating surfaces should not exceed the hardness of the BOPA-LOCK washers.
The unique wedge-locking action of the BOPA-LOCK washers can be easily verified. Tighten the bolted joint with BOPA-LOCK
washers, then loosen, during loosening, sliding must occur between the pair of BOPA-LOCK washers. Upon overriding of the cam faces a "click" should be felt when the bolt/nut
comes loose. Upon inspection the surfaces should show clear impression marks made by the BOPA-LOCK washers. When all these criteria are fulfilled, BOPA-LOCK washers will always lock bolted
joints exposed to severe vibration or dynamic loads.