View source for Ferrule

{{Short description|Ring used for fastening or joining}}
{{For|the plant of similar name|Ferula}}
{{Refimprove|date=July 2017}}
{{wiktionary}}
[[Image:Wire rope with thimble and ferrule.jpg|thumb|A [[wire rope]] terminated with a ferrule (left) and a [[Wire rope#Thimbles|thimble]] (right)]]
[[Image:Piccopipe.jpg|thumb|upright|[[Zuffolo | Picco pipe]] with nickel silver ferrule]]
[[File:brushtypes.jpg|thumb|right|upright=1.5|Non-circular ferrules holding bristles of a brush to its handle]]

A '''ferrule''' (a [[Corruption (linguistics)|corruption]] of [[Latin]] ''{{lang|la|viriola}}'' "small bracelet", under the influence of ''{{lang|la|ferrum}}'' "iron") is any of a number of types of objects, generally used for fastening, joining, sealing, or reinforcement. They are often narrow circular rings made from metal, or less commonly, plastic. Ferrules are also often referred to as '''eyelets''' or [[grommets]] within the [[manufacturing industry]].<ref>{{cite web|title=Ferrules & Eyelets |url=http://transmatic.com/Capabilities/FerrulesEyelets |publisher=Trans-Matic Manufacturing, Inc. |access-date=18 April 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140419025256/http://transmatic.com/Capabilities/FerrulesEyelets |archive-date=19 April 2014 }}</ref>

Most ferrules consist of a circular [[Clamp (tool)|clamp]] used to hold together and attach [[fiber]]s, [[wire]]s, or posts, generally by [[Crimp (joining)|crimping]], [[swaging]], or otherwise deforming the ferrule to permanently tighten it onto the parts that it holds.

==Examples==
*The sleeve, usually plastic or metal, on the end of a shoelace, preventing it from unraveling (called the [[aglet]])
*The metal sleeve which is crimped to hold the [[eraser]] in place on a [[pencil]]
*The metal band that binds the bristles or hair of a [[brush]] to its handle
*The metal ring which holds a [[chisel]] blade's [[Tang (tools)|tang]] to its handle
*In [[fiber optic]] terminations, glass or plastic fibers are bonded to precision [[ferrule connector]]s (FCs), also described as fiber channel connectors, and polished for splitting or connecting two fibers together.<ref>{{Ref patent
 |country=US
 |number=5016970
 |status=patent
 |title=Ferrule for optical fiber transmitting linearly polarized light and optical fiber connector using this ferrule
 |gdate=1991-05-21
 |fdate=1989-08-10
 |invent1=Mito Ryo Nagase
 |invent2=Machida Juichi Noda
 |invent3=Tachikawa Etsuji Sugita
}} ([http://www.patsnap.com/patents/view/US5016970.html download PDF]{{Dead link|date=December 2019 |bot=InternetArchiveBot |fix-attempted=yes }})</ref>
*The metal spike at the end of the shaft of an [[ice axe]]
*The margin of a cast crown that stabilizes root-canal-treated teeth in restorative dentistry<ref>[https://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=Search&Term=ferrule NIH search]</ref>
*A ferrule, in respect to [[dentistry]], is a band that encircles the external dimension of residual tooth structure, not unlike the metal bands that exist around a barrel.
*The bottom end of a flag stick on a golf course, which fits snugly into the hole in a cup
*The plastic sleeve that adorns the bottom of a steel or graphite [[golf club]] shaft just above the club head hosel. Originally designed to protect the shaft from damaging vibrations, it is now used mainly for aesthetic purposes.
*The metal band used to prevent the end of a wooden instrument or tool from splitting
*The semi-circular metal band that holds in place the fibers on the [[Bow frog|frog]] of a [[Bow (music)|bow]] for an instrument in the [[violin family]]
*[[Compression fitting]]s for attaching tubing (piping) commonly have ferrules (sometimes called ''olives'', especially in the UK) in them to make a liquid-tight connection
*A [[Wire rope#Swaged terminations|swaged termination]] type for wire rope
*The cap at the end of a [[Cane (walking stick)|cane]] or [[umbrella]] as well as the ring, often crimped, sometimes pinned, that prevents an umbrella's canopy from sliding off the end when open
*The portion of a [[Cue stick|cue]] in [[Cue sports|pool, billiards and snooker]] that tops the {{Cuegloss|Shaft|shaft}} and to which the {{Cuegloss|Cue tip|tip}} is bonded; historically made of [[ivory]], now typically made of [[fiberglass]], [[phenolic resin]], [[brass]] or [[titanium]].
*A joint between sections of a segmented [[fishing rod]] 
*A metal cap at the end of a cable housing with a hole on a bicycle or motorcycle control cable
*The metal sleeve that connects a [[hypodermic needle]] to a plastic [[Luer taper]] (which then connects to a [[syringe]] or [[intravenous therapy]] tubing)
*An [[electric wire ferrule]] is a metal tube [[Crimp connection|crimped]] over stranded wire to secure it within a [[screw terminal]], optionally with [[electrical insulation]] protecting any exposed portion of the wire not completely inside the screw terminal post.
*A rubber or plastic cap at the bottom end of a [[walking stick]].
*The metal tip on a staff carrying a [[flag]] or [[Guidon (heraldic flag)|guidon]] that finishes and protects the end of the wooden shaft.

==Reasons for use==
Some of the reasons people use ferrules include:<ref>{{cite web|title=Ferrules & Eyelets |url=http://transmatic.com/Capabilities/FerrulesEyelets |publisher=Trans-Matic Manufacturing, Inc. |access-date=18 April 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140419025256/http://transmatic.com/Capabilities/FerrulesEyelets |archive-date=19 April 2014 }}</ref>
* To ''shield'' parts or cables from [[electromagnetic pulses]], environmental damage, the elements, thermal factors, and more.
* To ''cover'' parts, adding wear resistance, damage protection, or packaging. 
* As a ''connector'', to connect wires, structural devices, and systems
* To ''bind'' parts together, including bundles of wires, or cloth threads to the end of the mop, as an example.
* To act as ''[[wikt:conveyance|conveyance]]'' for fluids like oil and water, or for gasses like air.

==References==
{{Reflist}}
{{Wiktionary}}

[[Category:Hardware (mechanical)]]
[[Category:Writing implements]]