Lock Nuts

Lock nuts prevent a bolted joint from working loose under vibration, shock or repeated dynamic loading — where a standard hex nut can gradually back off, a lock nut is designed to hold its preload. AIMS Industrial stocks lock nuts from Bremick, Hobson, Inox World, Champion and Bumax across nylon-insert (nyloc), all-metal stainless, cone-lock and high-tensile flanged/collared types, in zinc-plated, zinc-yellow, 304 and 316 stainless finishes. For more on selection, see our Types of Nuts: Hex, Nyloc, Wing, Flange & More Explained.

This collection covers the broader lock nut category. If you specifically need a nylon-insert nut, our dedicated Nylon Lock Nuts collection carries the full nyloc range across every metric, UNC, UNF and BSW size and finish we stock.

Quick Reference — Lock Nut Types We Stock

Lock Nut Types Stocked

Nyloc nuts (nylon insert lock nuts)

Our most widely stocked lock nut style. A nylon collar in the top of the nut deforms around the bolt thread, creating a grip that resists loosening without thread-locking compound. Generally suited to continuous service up to somewhere around 100–120°C depending on the nylon grade; treat as effectively single-use for safety-critical or high-vibration joints, since locking performance reduces each time the insert is run down a thread. See our full Nylon Lock Nuts range for the complete size and finish selection.

All-metal stainless hex lock nuts

A nylon-free, all-metal hex lock nut in 304 (A2) and 316 (A4) stainless, stocked in metric and UNC threads. Because there's no nylon insert, these aren't limited by an insert's temperature rating and hold up to repeated assembly cycles better than a nyloc nut — useful where a joint needs to be undone and retightened regularly, or where nylon isn't wanted near a process. Pair with our stainless fasteners range to keep bolts, nuts and washers in matching grades.

HCL cone lock nuts

An all-metal Hobson lock nut using a conical, crimped locking section rather than a nylon insert, stocked in UNC thread, Grade C, zinc-plated finish. Suited to high-temperature or reusable joints where a nyloc nut's nylon limit is a problem.

Bumax high-tensile flanged and collared lock nuts

Bumax is a Swedish manufacturer of premium stainless steel fasteners built to combine 316L (A4) corrosion resistance with high tensile strength. We stock their flanged and collared hex lock nuts, rated to Grade 8.8, for structural and marine applications that need stainless-grade corrosion resistance without giving up strength.

Materials and Finishes

• Zinc-plated steel — general industrial and indoor use, moderate corrosion resistance.
• Zinc-yellow passivate — chromate passivation over zinc for improved corrosion resistance, common in automotive and earthmoving use.
• 304 stainless steel (A2) — food-grade, general industrial and sheltered outdoor use.
• 316 stainless steel (A4) — severe marine and chemical exposure, including the Bumax high-tensile range.

Choosing Between Nyloc and All-Metal

For general workshop and trade use below the nylon insert's temperature limit, nyloc nuts are the default — easy to install, widely available and inexpensive. Step up to an all-metal option (stainless hex lock nut, HCL cone lock nut, or a Bumax high-tensile flanged/collared nut) where the joint runs hot, needs to be reused repeatedly, or sits in a process environment where nylon isn't appropriate. Always match the lock nut's grade and finish to the bolt being fastened — never pair a higher-grade nut with a lower-grade bolt, or vice versa.

Installation Notes

Tighten lock nuts to the torque specification for the bolt being secured. The locking element adds "running torque" — the extra resistance from the nylon insert or metal-to-metal grip — on top of normal seating torque, which can give a false impression of joint preload if a torque wrench reading isn't interpreted correctly. Use a calibrated torque wrench for safety-critical assemblies.

Companion Collections

• Nylon Lock Nuts — our dedicated nyloc range across every metric, UNC, UNF and BSW size we stock.
• Hex Lock Nuts — our wider range of non-nylon, all-metal hex lock nuts.
• Flanged Nuts — nuts with an integral bearing flange.
• Lock Washers — spring, internal/external tooth and Nord-Lock style washers as an alternative or supplement to a lock nut.
• Wedge Lock Washers — for severe vibration where a washer stack is preferred.
• Stainless Fasteners — matching stainless bolts and washers for marine and chemical applications.
• Nuts — our full nut range hub.
• Fasteners — the complete AIMS fastener range.

Order Lock Nuts from AIMS Industrial

Not sure whether your application needs a nyloc, all-metal or high-tensile lock nut? Our team can help you match the right type, grade and finish to your bolt and operating conditions. Call us on (02) 9773 0122, contact our team, or request a quote for bulk or trade pricing.

Frequently Asked Questions

What is a lock nut used for?
A lock nut is used anywhere a bolted joint is subject to vibration, shock or repeated movement and would otherwise gradually loosen — machinery, vehicles, structural connections and any dynamic-load assembly where maintaining preload matters.

What is the difference between a standard nut and a lock nut?
A standard hex nut holds a joint through thread friction and seating torque alone, which can reduce over time under vibration. A lock nut adds a second locking mechanism — a nylon insert, a crimped or conical metal section, or an integral flange — that provides extra resistance to loosening beyond plain thread friction.

Can lock nuts be removed?
Yes. Nyloc and all-metal lock nuts both unscrew with a standard spanner or socket, though you'll feel additional "running torque" from the locking element as it passes over the bolt thread. For safety-critical joints, replace a nyloc nut with a new one after removal rather than reusing it.

What are the disadvantages of using lock nuts?
Nyloc nuts are limited by the nylon insert's temperature rating and lose some locking performance each time they're reused. All-metal lock nuts avoid the temperature limit but generally cost more and can be harder to source in every size than a standard nyloc nut. Any lock nut also needs its running torque accounted for when checking joint preload with a torque wrench.

Do you stock all-metal (non-nylon) lock nuts?
Yes — we stock all-metal stainless hex lock nuts, HCL cone lock nuts and Bumax high-tensile flanged/collared lock nuts, all without a nylon insert, for higher-temperature or repeatedly reused joints.

What temperature can a lock nut handle?
It depends on the type. Nyloc nuts are generally rated to somewhere around 100–120°C depending on the nylon grade. All-metal lock nuts — stainless hex, HCL cone, and Bumax high-tensile — aren't limited by a nylon insert and suit hotter applications; check the specific product or ask our team for guidance.