Lock Nuts

Lock Nuts for Vibration-Resistant Fastening in Australian Industry

Lock nuts prevent loosening of bolted joints under vibration, shock, and dynamic loading. Where a standard hex nut backs off over time on machinery, vehicles, and infrastructure subject to repeated movement, a lock nut maintains preload and joint integrity. AIMS Industrial stocks lock nuts from Champion, Hobson, and Bremick across the common nyloc and all-metal types in zinc-plated, galvanised, and 316 stainless steel.

Lock nut types stocked

• Nyloc nuts (nylon insert lock nuts) — the most common workshop lock nut. A nylon collar in the top of the nut deforms around the bolt thread, creating friction that resists loosening. Suitable up to ~120°C; not recommended where temperatures exceed the nylon limit. Typically reusable 5–7 times before the insert wears
• All-metal prevailing torque nuts — distorted thread or crimped section creates metal-to-metal friction; suitable across the full operating temperature range of the parent material. Used in engines, exhaust systems, and high-temperature applications where nyloc isn't appropriate
• Flange lock nuts (serrated flange nuts) — integral serrated flange bites into the mating surface, providing both load distribution and locking action in one fastener. Common in automotive, agricultural, and machinery assembly
• K-lock nuts (Kep nuts) — captive serrated washer integrated with hex nut; the washer's serrations grip the joint surface to resist rotation

Materials and finishes

• Zinc-plated steel — for general industrial and indoor use; provides moderate corrosion resistance
• Hot-dip galvanised — heavier zinc coating for outdoor and structural applications
• 304 stainless steel (A2) — for food, marine, and corrosive environments
• 316 stainless steel (A4) — for severe marine and chemical exposure

Selection guidance

For general workshop and trade use, nyloc nuts are the default — easy to install, widely available, and reusable a few times. For applications above 120°C (engine bays, exhaust systems, industrial process equipment), step up to all-metal prevailing torque nuts. Match the grade and finish to the bolt being fastened — never combine a higher-grade nut with a lower-grade bolt or vice versa.

Installation notes

Tighten lock nuts to the same torque specification as the bolt being secured. The locking element adds running torque (the torque needed to spin the nut against the locking action) — this is over and above the seating torque. Use a torque wrench for safety-critical assemblies; the prevailing torque adds to total reading and can give a false impression of joint preload if not accounted for.

Related fastener products

See also: nylon lock nuts for the dedicated nyloc range, lock washers (Nordlock, spring, internal/external tooth), and stainless steel fasteners for marine and chemical applications.

For specific grade, finish, or thread requirements, contact our team.