Nylon Insert Locknuts are essential vibration-resistant fasteners designed to secure bolted joints under intense mechanical stress. Also known as nyloc nuts, these components feature a captive nylon collar that deforms over the mating bolt threads, creating a high-friction "prevailing torque" seal. Available in Grade 2, 5, and 8 steel as well as stainless steel, our inventory covers both metric and standard sizes for industrial, automotive, and aerospace applications. Browse our full selection of zinc-plated and galvanized finishes to find the perfect weather-resistant locking solution for your project.

Nylon Insert Locknut

Nylon insert locknuts deliver reliable, vibration-resistant clamping force that keeps your assemblies tight from first fit to final inspection. With our precision-cut threads and engineered inserts, you get confident locking without the mess of liquid threadlocker or extra hardware. Choose our locknuts to streamline builds, reduce maintenance checks, and protect uptime on the floor and in the field.

DIN 985

About Our Nylon Insert Locknuts

Our nylon insert locknuts use an interference-fit polymer collar that deflects over the mating threads as you tighten, creating a prevailing torque that resists loosening from shock, vibration, and thermal cycling. Because the insert acts directly on the thread crests, the joint stays secure while remaining serviceable, so you can remove and refit during inspections or changeovers without redesigning the fastener stack. 

A nylon insert locknut delivers consistent resistance along the full engagement length, which means less chance of backing off compared to plain hex nuts in dynamic environments. The insert helps damp micro-movement that can lead to joint relaxation, so torque retention remains predictable over time. The result is a cleaner bill of materials, faster assembly, and fewer callbacks for retorque.

If your project calls for adjacent options, consider pairing or substituting with our Prevailing Torque Locknut, our Hex Flange Nut With Nylon Insert for added bearing surface, or our Nylon Insert Heavy Duty Locknut when you need extra thread engagement for demanding loads.

Standard Pattern: DIN 985 Nylon Insert Locknuts

Our standard pattern aligns with DIN 985, the widely adopted specification for general-duty nylon insert locknuts. Functionally similar to the taller-insert DIN 982 pattern, DIN 985 is optimized for mainstream applications where reliable locking is essential without the added height of extended collars. It’s the everyday workhorse you reach for when you want simple, repeatable performance.

Installation & Torque Tips

For best results, start threads by hand to ensure true alignment, then tighten to the joint’s specified torque so the insert fully engages and the clamp load settles correctly. Aim for at least two full threads protruding past the top of the nut after tightening, which confirms full insert contact and helps with future inspections. On critical joints, follow a cross-pattern sequence and verify torque after a brief dwell to account for embedment and seating.

Fit, Sizes & Applications

Our nylon insert locknuts are available in common diameters and pitches to match your preferred fastener standards across equipment frames, guards, enclosures, bracketry, and motion systems. They’re a natural fit for conveyor assemblies, light machinery, HVAC housings, fixtures, automotive sub-assemblies, racking, and field-serviceable components where you want strong retention without permanent adhesives. Use them anywhere you need dependable prevailing torque and straightforward maintenance.

FAQs

What is a nylon insert locknut and how does it work?

A nylon insert locknut is a hex nut with a polymer collar at the top that creates friction against the bolt’s threads. As you tighten, the insert elastically deforms and grips the thread crests, generating prevailing torque that resists loosening from vibration and shock.

When should a nylon insert locknut be used instead of a standard hex nut?

Choose a nylon insert locknut when the joint will see vibration, dynamic loads, or frequent start-stop cycles and you want built-in resistance to back-off. It’s also ideal when you prefer a clean, serviceable solution without liquid threadlocker, lock washers, or specialty hardware.

Can a nylon insert locknut be reused after removal?

Yes, within reason: the insert can tolerate a limited number of install-remove cycles while still providing functional prevailing torque. If you notice noticeably reduced resistance during tightening, visible damage to the collar, or the joint is safety-critical, replace the locknut to maintain specification.

What temperature limitations affect the performance of nylon insert locknuts?

Nylon inserts are sensitive to elevated temperatures that can soften the polymer and reduce prevailing torque, as well as to very low temperatures that can make the insert less compliant during assembly. For applications that consistently run at higher or lower extremes, select a locking solution rated for those conditions or validate performance with on-bench testing before deployment.