Hex Lock Nuts

Hex Lock Nut Selection — Quick Reference

Lock nuts prevent vibration loosening of bolted joints — reliable fastening in machinery + vehicles + infrastructure subject to vibration + dynamic loading. Selection by locking method (nylon insert vs all-metal vs flange + serrated).

Critical: Nyloc nuts rated to ~120°C max — nylon degrades above this. For higher temperatures use all-metal locking nuts. Match nut grade to bolt grade — Grade 8 nyloc nut + Grade 8 bolt; mixing grades = lower of two governs joint strength. For critical service (aircraft + structural + safety-critical): castle nut + cotter pin = mechanical positive lock that exceeds nylon/distorted methods. Companion: lock washers, flanged nuts, castle nuts, all fasteners.

Hex Lock Nuts — Nyloc & All-Metal Prevailing Torque Nuts

Lock nuts prevent vibration loosening of bolted joints — providing reliable fastening in machinery, vehicles, and infrastructure subject to vibration, shock, and thermal cycling. AIMS Industrial sells hex lock nuts in nyloc (nylon insert) and all-metal prevailing torque configurations — zinc-plated, galvanised, and stainless steel from M4 to M30 for the full range of industrial fastening applications.

Lock Nuts We Stock

• Nyloc Lock Nuts (DIN 985): Nyloc nuts have a nylon insert in the top section of the nut — the bolt thread deforms the nylon, creating resistance to rotation that prevents the nut from backing off under vibration. Nyloc nuts are the most common vibration-resistant nut in general industrial, automotive, and machinery applications.
• All-Metal Prevailing Torque Nuts (DIN 980): All-metal lock nuts (Philidas, oval top) use a deformed nut top section to create thread interference — providing locking action without a nylon element. Suitable for high-temperature applications (above 120°C) where nylon would soften and lose locking function.
• Stainless Steel Nyloc Nuts: 316 stainless steel nyloc lock nuts for corrosive and food-grade applications — standard in marine, food processing, and pharmaceutical equipment assemblies. The nylon insert in stainless nyloc nuts is typically rated to 120°C.
• Galvanised Nyloc Nuts: Hot-dip galvanised nyloc lock nuts for outdoor structural and infrastructure applications — matching HDG bolt assemblies in fencing, sign structures, and general outdoor construction.
• Size Range M4 to M30: Nyloc and all-metal lock nuts in M4 through M24 for standard machinery and equipment; M30 available for heavy structural applications.

Lock Nut Selection Guide

• Temperature Limit for Nyloc: The nylon insert in nyloc nuts is rated to approximately 120°C (some grades to 150°C). Above this temperature, the nylon softens and loses its locking function — use all-metal prevailing torque nuts in high-temperature locations near engines, exhaust systems, and industrial heating equipment.
• Single-Use Limitation: Nyloc nuts should not be reused — the nylon insert is partially deformed on first use and provides reduced locking performance on re-installation. All-metal lock nuts have greater reuse tolerance but also lose performance after repeated use.
• Lock Nut vs Lock Washer: Nyloc lock nuts provide thread resistance to rotation; spring washers provide axial preload recovery. The two mechanisms work differently — nyloc nuts are preferred where the nut must not back off; spring washers are preferred where maintaining joint preload under settling or thermal cycling is the primary concern.

Australian Business, Local Supply: As a proudly Australian business since 1988, we stock locally and work with trusted local Australian manufacturers and distributors to ensure fast, reliable supply.

Expert Support: Need help buying the right product for your application? Contact our team for application-specific advice or request a quote.

See our full fasteners range including hex bolts and nuts, lock washers, and flanged nuts.