All-Metal Lock Nuts

All-metal lock nuts resist loosening through a deformed thread or distorted top section that grips the bolt — no nylon insert. This makes them suitable for high-temperature and heavy-duty applications where nylon-insert nuts would fail. We stock all-metal lock nuts across grades and materials for demanding locking jobs.

How They Lock

The nut's top threads are intentionally distorted (pinched, slotted, or oval) so they must elastically deform over the bolt threads, creating prevailing torque — resistance that holds the nut in place under vibration. Because the locking is metal-on-metal, it works at temperatures that would melt or soften a nylon insert.

All-Metal vs. Nylon Insert

Choose all-metal for temperatures above 250°F, heavy vibration, or where nylon's chemical/temperature limits are a problem. Choose nylon insert for lower-temperature general use and more reuses. All-metal lock nuts have a lower reuse count — the thread distortion wears with each cycle.

Materials

Steel (Grade 5/8 equivalent) with zinc or phosphate finish for strength and general use. 18-8 and 316 stainless for corrosion resistance, where the all-metal design also avoids stainless galling concerns better than some alternatives.

Dimensional Standards

All-metal prevailing-torque lock nuts follow DIN 980 (metric) and IFI/ASME prevailing-torque standards (inch).

Selecting the Right All-Metal Lock Nut

Choose all-metal for high temperature, heavy vibration, or harsh environments. Match grade to the bolt and material to the environment. Expect fewer reuses than nylon-insert nuts. Verify thread pitch, and use anti-seize on stainless to prevent galling during the high-friction installation.

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