Description

AM Steel Lock Nuts are self-locking, prevailing-torque nuts designed to stay tight under vibration and dynamic loads where a standard hex nut could gradually work loose. The most common type – the nylon insert lock nut, or nyloc – carries an unthreaded nylon collar at its top; as the nut is tightened, the bolt cuts its own path through the insert, and the nylon grips the thread to resist loosening. Manufactured under the AM Steel brand to DIN 985 (ISO 10511), these nuts (widely known as nyloc nuts, self-locking nuts, or nylon insert nuts) are the go-to fastening wherever a joint is subject to movement, vibration, or repeated loading.

Because the locking action comes from the insert rather than from over-tightening, AM Steel lock nuts hold securely without needing a separate spring washer or thread-locking compound – making them fast, clean, and reliable in service. They’re widely used in machinery and equipment, automotive and transport, pumps and motors, and any assembly exposed to vibration. AM Steel also supplies all-metal prevailing-torque lock nuts (DIN 980) for high-temperature applications beyond the nylon insert’s limit, where a deformed metal thread section provides the locking action instead. Lock nuts are matched by strength class to the bolt they’re used with – steel versions in property classes such as 8 and 10 – so the nut is never the weak point in the joint. AM Steel lock nuts are available in carbon and high-tensile steel (zinc-plated or yellow-passivated) for general work, and in stainless steel (A2/304 and A4/316, the latter considered marine-grade) for outdoor, wet, and coastal environments where corrosion resistance is critical.

Whether you’re assembling machinery, working on automotive and transport equipment, fixing pumps and motors, or handling any joint exposed to vibration, AM Steel lock nuts deliver the vibration-resistant grip, matched strength, and consistent quality needed for secure, long-lasting fastening. As with all AM Steel products, this lock nut is available in a range of metric sizes (typically M3 to M20 for nylon insert, larger for all-metal types, per DIN 985 / DIN 980), in multiple grades, materials, and finishes to suit both industrial-grade and everyday fastening needs.

Key features:

• Prevailing-torque locking action resists loosening under vibration and dynamic loads
• Nylon insert (nyloc) grips the bolt thread without needing a spring washer or thread locker
• All-metal (DIN 980) versions available for high-temperature applications beyond the nylon limit
• Manufactured to DIN 985 / ISO 10511 (nylon insert) dimensional standards
• Available in property classes 8 and 10 (steel) matched to bolt strength
• Available in carbon steel (zinc-plated, yellow-passivated) and stainless steel (A2/304, A4/316)
• Backed by the quality assurance of AM Steel

Ideal For

AM Steel Lock Nuts are ideal for:

• Machinery and equipment assembly subject to vibration, movement, or repeated loading
• Automotive, transport, and mobile equipment connections that must not work loose in service
• Pumps, motors, fans, and rotating machinery where dynamic loads loosen standard nuts
• Maintenance and repair trades needing a reliable self-locking nut without extra washers or thread locker
• General assembly wherever a joint requires vibration resistance and long-term security

Choosing the Right Lock Nut

Selecting the correct lock nut from the AM Steel range depends on several factors:

• Locking Type – Nylon insert (nyloc) for general vibration resistance; all-metal (DIN 980) where temperatures exceed the nylon insert’s limit or in extreme conditions.
• Material – Stainless steel (A2/304 or A4/316) for outdoor, wet, or corrosion-prone applications; carbon or high-tensile steel for general work.
• Strength Class – Match the nut’s property class (e.g. class 8 or 10) to the bolt grade so the nut is never the weak point in the joint.
• Thread Size & Pitch – Choose the diameter and pitch (coarse or fine) to match the mating bolt, screw, or threaded rod exactly.
• Temperature – Nylon insert nuts are limited to moderate temperatures (typically up to around 120°C); above this, use an all-metal lock nut.
• Reuse Frequency – Nyloc nuts lose locking effectiveness after repeated removal; for frequently disassembled joints, plan to replace them or use an all-metal type.

Strategies to Choose the Right Product

• Pick the locking type for the temperature – Use nylon insert nuts for general vibration resistance; switch to all-metal (DIN 980) lock nuts where heat would soften or degrade the nylon.
• Match the nut class to the bolt grade – Pair the property class to the bolt (e.g. class 8 nut with an 8.8 bolt) so the joint reaches its intended strength.
• Replace nyloc nuts after removal – The nylon insert deforms to the thread on first use; for a reliable lock, fit a new nyloc nut rather than reusing one that’s been removed.
• Match material to environment – Use stainless steel (A2/304 or A4/316) for outdoor, wet, or coastal work; zinc-plated or yellow-passivated steel for general dry conditions.
• Guard against galling in stainless – When threading stainless lock nuts onto stainless bolts, use an anti-seize lubricant to prevent thread galling and seizing.
• Match thread size and pitch exactly – Confirm both diameter and coarse/fine pitch against the mating bolt to ensure correct engagement of the locking feature.

Mechanical Properties

AM Steel Lock Nuts are manufactured to meet recognized mechanical and dimensional standards, ensuring reliability across machinery, automotive, and vibration-prone assembly applications:

These mechanical ratings confirm that AM Steel lock nuts deliver secure, vibration-resistant fastening suited to machinery, automotive, and dynamic-load applications – match the locking type to the temperature, pair the property class to the bolt grade, and fit a fresh nut after removal for a reliable lock.

Frequently Asked Questions (FAQs)

1. What is a lock nut used for?
A lock nut is used wherever a joint is exposed to vibration, movement, or repeated loading and a standard nut could work loose – its prevailing-torque locking action keeps the connection tight in machinery, automotive, and dynamic-load assemblies.

2. How does a nylon insert lock nut work?
The nut has an unthreaded nylon collar at its top; as it’s tightened, the bolt forms its own path through the insert, and the nylon grips the bolt thread to create friction that resists loosening under vibration.

3. What’s the difference between a lock nut and a standard hex nut?
A standard hex nut relies on correct torque and thread friction to stay put, while a lock nut has a built-in locking feature – a nylon insert or a deformed metal thread – that actively resists loosening under vibration.

4. Are AM Steel lock nuts different from generic lock nuts?
AM Steel lock nuts are manufactured and quality-tested under the AM Steel brand, ensuring consistent thread quality, insert grip, strength class, and finish across every batch, per DIN 985 / ISO 10511.

5. What’s the difference between a nylon insert and an all-metal lock nut?
A nylon insert (nyloc) nut locks via a nylon collar and suits general, moderate-temperature use, while an all-metal lock nut (DIN 980) locks via a deformed thread section and is used where high temperatures would degrade the nylon.

6. Can lock nuts be reused?
Nylon insert lock nuts lose locking effectiveness once removed, because the insert deforms to the thread on first use; for a reliable lock, fit a new nyloc nut rather than reusing one – all-metal types tolerate more re-use.

7. What temperature can a nylon insert lock nut handle?
Nylon insert lock nuts are generally limited to around 120°C; above this the nylon can soften and lose its grip, so an all-metal lock nut should be used for higher-temperature applications.

8. What sizes do lock nuts come in?
AM Steel nylon insert lock nuts are available in a range of sizes, typically M3 to M20, with larger sizes available in all-metal types, per DIN 985 / DIN 980.

9. Do I still need a washer with a lock nut?
The locking action doesn’t require a spring washer, but a plain washer is often still used to spread the clamping load and protect the surface – particularly on softer materials.

10. Are lock nuts corrosion-resistant?
Yes, especially AM Steel stainless steel versions (A2/304 or A4/316), which resist rust in outdoor, wet, or coastal environments; zinc-plated and yellow-passivated steel offer protection for general and dry conditions.

11. Which way up does a nylon insert lock nut go?
The nylon insert must face away from the joint, so the bolt enters the metal-threaded end first and reaches the nylon collar last – fitting it the wrong way round prevents the insert from locking correctly.

12. What property class should my lock nut be?
Match the lock nut’s property class to the bolt grade – for example a class 8 nut with an 8.8 bolt, or class 10 with a 10.9 bolt – so the nut is never the weak point in the joint.

13. What’s the difference between A2 and A4 stainless steel lock nuts?
A2 (304) stainless offers good general corrosion resistance for most indoor and outdoor use, while A4 (316), considered marine-grade, provides superior resistance to chlorides and coastal or chemical environments.