NFE 25-511 Conical Lock Washers
The NF E 25-511 conical lock washer is a spring-steel fastener that resists loosening through tension rather than friction alone. Its conical body is slightly taller than the relaxed gap, so when the joint is tightened the washer is flattened and stores spring energy; this continuous compensatory preload keeps the bolt loaded even as the joint settles or the surfaces wear. At the same time, staggered radial serrations on the washer faces embed into the bolt head or nut and the mating surface, creating a mechanical lock that resists rotation.
Together these effects hold the connection tight under intense vibration, thermal cycling and high alternating loads — conditions that defeat ordinary flat washers. The design also maintains good electrical contact, which matters for busbar and grounding joints where conductive stability is as important as mechanical security, making it a proven counter to bolt-fatigue loosening.
Holding both mechanically and through stored spring preload, it is the established defense against bolt-fatigue loosening in vibrating, current-carrying joints.
Specified for threaded joints that must survive vibration and stay electrically stable, these washers serve electrical busway connections, rail transit bogies, large generator sets and automotive powertrains. They are the professional solution for managing industrial-grade vibration and preventing bolt-fatigue loosening.
From busways and bogies to generators and powertrains, it keeps bolted joints tight, conductive and fatigue-free under real-world vibration and shock loads.
