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Silver steel lock nut with nylon insert, hexagonal shape

MIDWEST FASTENER CORP

MIDWEST FASTENER CORP 66662 Nylon Insert Lock Nut 5/8"-18 Steel Grade 2 Zinc

SKU CH-2W45-QT5KH

Steel Grade 2 zinc lock nut with nylon insert resists vibration loosening on 5/8"-18 threads

  • Product typeNuts
  • Resists loosening under vibration thanks to nylon insert
  • 5/8"-18 thread fits matching bolts and studs
  • Steel Grade 2 construction provides standard fastening strength
  • Zinc finish protects against corrosion in everyday use
  • Manufacturer part number 66662 identifies the exact specification

Product identity

This MIDWEST FASTENER lock nut uses a nylon insert to resist loosening under vibration and torque. It is supplied new in a Grade 2 steel body with a zinc finish and a 5/8"-18 thread pitch. The fastener suits maintenance, repair and assembly tasks where a secure threaded joint is required.

Upgrade context

The nylon insert replaces a plain hex nut when the joint must stay tight without additional locking hardware such as washers or adhesives. The step up is worth it on equipment that sees repeated vibration or thermal cycling where a standard nut would back off over time.

Sustained behaviour

Under continuous vibration the nylon collar maintains prevailing torque by deforming against the bolt threads, keeping the joint clamped without retightening. The zinc coating provides baseline corrosion resistance for general indoor or sheltered outdoor exposure. Grade 2 steel limits the nut to moderate clamping loads rather than high-strength structural duty.

How it compares

Measured against everything we stock in General Hardware & Accessories, at today’s prices. Recalculated every night.

Price $9.99
Cheaper than about 80% of the 2,607 comparable items (median $18.99).

Specifications

Product
Brand nameMIDWEST FASTENER
Product typeNuts

Questions about this item

What thread size does the 5/8"-18 lock nut require on the bolt or stud?

It requires a 5/8"-18 thread pitch on the mating bolt or stud for proper engagement.

How do you install the nylon insert lock nut, and what is the common mistake?

Thread it by hand until the nylon insert contacts the bolt, then tighten with a wrench; the common mistake is using an impact driver, which can overheat and damage the nylon.

When should the nylon insert lock nut be replaced?

Replace it whenever the nut is removed, because the nylon insert deforms during the first use and loses its locking grip if reused.

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