An acorn nut, also referred to as crown hex nut, blind nut, cap nut, domed cap nut, or dome nut (UK), is a

nut Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed, or a collective noun for dry and edible fruits or seeds * Nut (hardware), fastener used with a bolt Nut or Nuts may also refer to: Arts, entertainment, and media Co ...

that has a domed end on one side. When used together with a

threaded fastener A fastener (US English) or fastening (UK English) is a hardware device that mechanically joins or affixes two or more objects together. In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or disman ...

with an external male thread, the domed end encloses the external thread, either to protect the thread or to protect nearby objects from contact with the thread. In addition, the dome gives a more finished appearance. Acorn nuts are usually made of

brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other with ...

steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...

stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...

(low

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

content) or

nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from petro ...

. They can also be chrome plated and given a mirror finish. There are two types of acorn nuts. One is low, or the standard acorn nut. The other is the high acorn nut. The high acorn nut is wider and higher and will protect extra long studs. There are also self-locking acorn nuts that have distorted threads in the hex area to create a tight friction fit to prevent the nut from vibrating loose. There are standards governing the manufacture of acorn nuts. One is

Society of Automotive Engineers SAE International, formerly named the Society of Automotive Engineers, is a United States-based, globally active professional association and standards developing organization for engineering professionals in various industries. SAE Internatio ...

(SAE) Standard J483, High and Low Crown (Blind, Acorn) Hex Nuts. Another is Deutsches Institut für Normung ( DIN) 1587, Hexagon Domed Cap Nuts.

References

Nuts (hardware) {{Mech-engineering-stub