Ferrule

A ferrule (a corruption of Latin viriola ”small bracelet,” under the influence of ferrum ”iron.”) is a name for types of metal objects, generally used for fastening, joining, or reinforcement. They are often narrow circular rings of metal, or less commonly, plastic.

Most ferrules consist of a circular clamp used to hold together and attach fibers, wires or posts, generally by crimping, swaging, or otherwise deforming the ferrule to permanently tighten it onto the parts that it holds.

Examples

• The plastic sleeve preventing the ends of shoelaces from unraveling (called the aglet)
• The metal sleeve which is crimped to hold the eraser in place on pencils
• 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 to the handle
• In fiber optic terminations, glass or plastic fibers are bonded to precision ferrules and polished for splitting or connecting two fibers together^[1]
• 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^[2]
• The bottom end of a flag stick on a golf course, which fits snugly into a hole in the cup
• The plastic sleeve that adorns the bottom of most steel and graphite golf club shafts 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 ends of wooden instruments from splitting
• The semi-circular metal band that holds the fibers in place on the Frogs of bows for violin family instruments
• Compression fittings for attaching tubing (piping) commonly have ferrules in them.
• A swaged termination type for wire rope
• The cap at the end of a cane or umbrella.
• The portion of a cue in pool, billiards and snooker that tops the shaft and to which the tip is bonded; historically made of ivory, now typically made of fiberglass, phenolic resin or brass
• The male and female joints that join one section of a two-piece fishing rod
• A metal cap at the end of cable housing with a hole on bicycle or motorcycle control cables
• The metal sleeve that connects a hypodermic needle to a plastic luer taper (which then connects to a syringe or intravenous therapy tubing.)
• A metal tube crimped over stranded wire to secure it within a screw terminal usually with electrical insulation protecting any exposed portion of the wire not completely inside the screw terminal post.