Cap & Acorn Nuts vs. Nyloc Nuts
Comparing 2 standards across 10 specifications. 10 key differences identified.
Cap and Acorn nuts (standardized under DIN 1587 and ASME B18.2.2) feature a domed, blind-ended crown that completely encloses the protruding end of a mating screw or threaded rod. They prevent snagging on clothing, protect exposed threads from corrosion and moisture, and provide a finished decorative appearance on consumer goods, bicycles, and furniture.
The Nyloc Nut (Nylon-Insert Lock Nut / Prevailing Torque Nut, standardized under ISO 7040 and DIN 985) incorporates a non-threaded polymer nylon ring permanently captured in an upper crown collar. When threaded onto a bolt, the nylon insert deforms elastically around the bolt threads, generating high frictional prevailing torque that prevents vibrational back-off.
Specification Comparison Table
10 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Specifications
|
DIN 1587 (High type dome) / DIN 917 (Low profile cap) / ASME B18.2.2 | ISO 7040 (Standard height) / ISO 10511 (Low profile) / DIN 985 / ASME B18.16.6 |
|
Primary Applications
|
Bicycle axle hubs, motorcycle engine covers, outdoor playground structures, furniture | Automotive suspension, aircraft, lawnmowers, go-karts, robotic actuators |
|
Dome Profile
|
Hemispherical blind cap permanently enclosing internal tapped threads | — |
|
Safety Function
|
Eliminates sharp exposed screw threads that cause lacerations or fabric snags | — |
|
Environmental Protection
|
Seals internal thread engagement from weather, road salt, and industrial grime | — |
|
Common Materials
|
A2/A4 Stainless steel, solid brass, chrome-plated steel, black oxide steel | — |
|
Locking Mechanism
|
— | Radial elastic compression of unthreaded polyamide nylon collar |
|
Operating Temperature Range
|
— | -50°C to +120°C (-58°F to +248°F) |
|
Prevailing Torque Behavior
|
— | Maintains locking friction even without axial bolt preload (free-spinning torque) |
|
Reusability Guidelines
|
— | Reusable 2 to 3 times before nylon wear reduces prevailing torque below safety limits |