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 dismantled without damaging the joining components.

Welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as bra ...

is an example of creating permanent joints. Steel fasteners are usually made of stainless steel, carbon steel, or

alloy steel Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low alloy steels and high alloy steels. The differe ...

. Other alternative methods of joining materials include: crimping,

welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as bra ...

, soldering, brazing,

taping Athletic taping is the process of applying tape directly to the skin or over pre-wrap in order to maintain a stable position of bones and muscles during athletic activity. It is a procedure that uses athletic tape (pressure-sensitive tape similar ...

gluing Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...

, or the use of other adhesives. Force may also be used, such as with

magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nicke ...

s, vacuum (like suction cups), or even

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of ...

(like sticky pads). Some types of woodworking joints make use of separate internal reinforcements, such as dowels or biscuits, which in a sense can be considered fasteners within the scope of the joint system, although on their own they are not general purpose fasteners. Furniture supplied in

flat-pack Ready-to-assemble furniture (RTA), also known as knock-down furniture (KD), flat pack furniture, or kit furniture, is a form of furniture that requires customer assembly. The separate components are packed for sale in cartons which also contain ...

form often uses cam dowels locked by cam locks, also known as conformat fasteners. Fasteners can also be used to close a container such as a bag, a box, or an envelope; or they may involve keeping together the sides of an opening of flexible material, attaching a lid to a container, etc. There are also special-purpose closing devices, e.g. a bread clip. Items like a

rope A rope is a group of yarns, plies, fibres, or strands that are twisted or braided together into a larger and stronger form. Ropes have tensile strength and so can be used for dragging and lifting. Rope is thicker and stronger than similar ...

, string,

wire Overhead power cabling. The conductor consists of seven strands of steel (centre, high tensile strength), surrounded by four outer layers of aluminium (high conductivity). Sample diameter 40 mm A wire is a flexible strand of metal. Wire is c ...

cable Cable may refer to: Mechanical * Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof * Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...

, chain, or plastic wrap may be used to mechanically join objects; but are not generally categorized as fasteners because they have additional common uses. Likewise, hinges and springs may join objects together, but are ordinarily not considered fasteners because their primary purpose is to allow articulation rather than rigid affixment.

Industry

In 2005, it was estimated that the United States fastener industry runs 350 manufacturing plants and employs 40,000 workers. The industry is strongly tied to the production of automobiles, aircraft, appliances, agricultural machinery, commercial construction, and infrastructure. More than 200 billion fasteners are used per year in the U.S., 26 billion of these by the automotive industry. The largest distributor of fasteners in North America is the Fastenal Company.

Materials

There are three major steel fasteners used in industries: stainless steel, carbon steel, and alloy steel. The major grade used in stainless steel fasteners: 200 series, 300 series, and 400 series. Titanium, aluminium, and various alloys are also common materials of construction for metal fasteners. In many cases, special coatings or plating may be applied to metal fasteners to improve their performance characteristics by, for example, enhancing corrosion resistance. Common coatings/platings include zinc, chrome, and hot dip galvanizing.

Applications

When selecting a fastener for industrial applications, it is important to consider a variety of factors. The threading, the applied load on the fastener, the stiffness of the fastener, and the number of fasteners needed should all be taken into account. When choosing a fastener for a given application, it is important to know the specifics of that application to help select the proper material for the intended use. Factors that should be considered include: *Accessibility *Environment, including temperature, water exposure, and potentially corrosive elements *Installation process *Materials to be joined *Reusability *Weight restrictions

Types

A threaded fastener has internal or external screw threads. The most common types are the

screw A screw and a bolt (see '' Differentiation between bolt and screw'' below) are similar types of fastener typically made of metal and characterized by a helical ridge, called a ''male thread'' (external thread). Screws and bolts are used to f ...

, nut and bolt, possibly involving

washers Washer most commonly refers to: * Washer (hardware), a thin usually disc-shaped plate with a hole in the middle typically used with a bolt or nut *Washing machine, for cleaning clothes Washer may also refer to: *Dishwasher, a machine for clean ...

. Other more specialized types of threaded fasteners include captive threaded fasteners,

stud Stud may refer to the following terms: Animals * Stud (animal), an animal retained for breeding ** Stud farm, a property where livestock are bred Arts and entertainment * Stud (band), a British progressive rock group * The Stud (bar), a gay ba ...

, threaded inserts, and

threaded rod A threaded rod, also known as a stud, is a relatively long rod that is threaded on both ends; the thread may extend along the complete length of the rod. They are designed to be used in tension. Threaded rod in bar stock form is often called all ...

s. Other types of fastener include: * anchor bolt *

batten A batten is most commonly a strip of solid material, historically wood but can also be of plastic, metal, or fiberglass. Battens are variously used in construction, sailing, and other fields. In the lighting industry, battens refer to linea ...

* bolt (fastener) **

* bolt snap *

brass fastener A brass fastener, butterfly clips, brad, paper fastener or split pin is a stationery item used for securing multiple sheets of paper together. A patent of the fastener was issued in 1866 to George W McGill. The fastener is inserted into punched ...

buckle The buckle or clasp is a device used for fastening two loose ends, with one end attached to it and the other held by a catch in a secure but adjustable manner. Often taken for granted, the invention of the buckle was indispensable in securing tw ...

button A button is a fastener that joins two pieces of fabric together by slipping through a loop or by sliding through a buttonhole. In modern clothing and fashion design, buttons are commonly made of plastic but also may be made of metal, wood, o ...

cable tie A cable tie (also known as a hose tie, zip tie, or tie wrap) is a type of fastener for holding items together, primarily electrical cables and wires. Because of their low cost, ease of use, and binding strength, cable ties are ubiquitous, findi ...

cam Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...

* captive fastener * clamp (or cramp) **

hose clamp A hose clamp (hose clip, hose lock or Jubilee clip (UK)) is a device used to attach and seal a hose onto a fitting such as a barb or nipple. Types Many types are available, including : Screw/band (worm gear) clamps Screw clamps consist of a ...

* clasp and shackle ** bolt snap **

carabiner A carabiner or karabiner () is a specialized type of shackle, a metal loop with a spring-loaded gate used to quickly and reversibly connect components, most notably in safety-critical systems. The word is a shortened form of ''Karabinerhaken'' ...

** circle cotter **

lobster clasp A lobster clasp, also known as a lobster hook, lobster claw, trigger clasp, or bocklebee clasp, is a fastener that is held closed by a spring. The lobster clasp is opened or closed by holding a small lever, usually with a fingernail, long enough ...

* cleco * clip ** circlip ** hairpin clip **

paper clip A paper clip (or paperclip) is a tool used to hold sheets of paper together, usually made of steel wire bent to a looped shape (though some are covered in plastic). Most paper clips are variations of the ''Gem'' type introduced in the 1890s or e ...

** terry clip * clutch *

drawing pin A drawing pin (in British English) or thumb tack (in North American English) is a short nail or pin used to fasten items to a wall or board for display and intended to be inserted by hand, usually using the thumb. A variety of names is used ...

(thumbtack) * flange *

frog A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" ''Triadobatrachus'' is ...

grommet Curtain grommets, used among others in shower curtains. A grommet is a ring or edge strip inserted into a hole through thin material, typically a sheet of textile fabric, sheet metal or composite of carbon fiber, wood or honeycomb. Grommets ar ...

hook-and-eye closure A hook-and-eye closure is a simple and secure method of fastening garments together. It consists of a metal hook, commonly wire bent to shape, and an eye (or "eyelet") of the same material into which the hook fits. History The hook and eye clo ...

hook and loop fastener Hook-and-loop fasteners, hook-and-pile fasteners or touch fasteners (often referred to by the genericized trademark velcro, due to the prominence of the Velcro Brand) consist of two components: typically, two lineal fabric strips (or, alterna ...

Velcro Velcro, officially known as Velcro IP Holdings LLC and trading as Velcro Companies, is a British privately held company, founded by Swiss electrical engineer George de Mestral in the 1950s. It is the original manufacturer of hook-and-loop fast ...

latch A latch or catch (called sneck in Northern England and Scotland) is a type of mechanical fastener that joins two (or more) objects or surfaces while allowing for their regular separation. A latch typically engages another piece of hardware on t ...

nail Nail or Nails may refer to: In biology * Nail (anatomy), toughened protective protein-keratin (known as alpha-keratin, also found in hair) at the end of an animal digit, such as fingernail * Nail (beak), a plate of hard horny tissue at the tip ...

and

rivet A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite to the head is called the ''tail''. On installation, the rivet is placed in a punched ...

** solid/round head rivets ** semi-tubular rivets ** blind (pop) rivet * pegs **

clothespin A clothespin (US English), or clothes peg (UK English) is a fastener used to hang up clothes for drying, usually on a clothes line. Clothespins come in many different designs. Design During the 1700s laundry was hung on bushes, limbs or lin ...

tent peg A tent peg (or tent stake) is a spike, usually with a hook or hole on the top end, typically made from wood, metal, plastic, or composite material, pushed or driven into the ground for holding a tent to the ground, either directly by attaching to t ...

* PEM nut *

pin A pin is a device used for fastening objects or material together. Pin or PIN may also refer to: Computers and technology * Personal identification number (PIN), to access a secured system ** PIN pad, a PIN entry device * PIN, a former Dutch ...

s ** clevis fastener ** cotter ** dowel ** linchpin **

R-clip __NOTOC__ An R-clip, also known as an R-pin, R-key, hairpin cotter pin, hairpin cotter,. bridge pin, hitch pin clip or spring cotter pin, is a fastener made of a durable but flexible material, commonly hardened metal wire, resembling the shape of ...

safety pin The safety pin is a variation of the regular pin which includes a simple spring mechanism and a clasp. The clasp forms a closed loop to properly fasten the pin to whatever it is applied to and covers the end of the pin to protect the user from t ...

** split pin ** spring pin ** tapered pin * retaining rings ** circlip ** e-ring * rivet-like ** well nut *

rock bolt A rock bolt is a long anchor bolt, for stabilizing rock excavations, which may be used in tunnels or rock cuts. It transfers load from the unstable exterior to the confined (and much stronger) interior of the rock mass. Rock bolts were first use ...

rubber band A rubber band (also known as an elastic band, gum band or lacky band) is a loop of rubber, usually ring or oval shaped, and commonly used to hold multiple objects together. The rubber band was patented in England on March 17, 1845 by Stephen P ...

(or bands of other materials) * screw anchor *

snap fastener A snap fastener, also called snap button, press stud, press fastener, dome fastener, popper, snap and tich (or tich button), is a pair of interlocking discs, made out of a metal or plastic, commonly used in place of traditional buttons to fasten ...

* snap-fit * staple * stitches * strap * tie *

toggle bolt A toggle bolt, also known as a butterfly anchor, is a fastener for hanging objects on hollow walls such as drywall. Toggle bolts have wings that open inside a hollow wall, bracing against it to hold the fastener securely.New Fix-it yourself manual ...

tolerance rings Tolerance rings are radially sprung rings that are press fitted between two mating components to act as frictional fasteners. They are flexible shims designed to fix two cylindrical parts together. The wavelike protrusions that run around the circu ...

* treasury tag * twist tie * wedge anchor *

zipper A zipper, zip, fly, or zip fastener, formerly known as a clasp locker, is a commonly used device for binding together two edges of fabric or other flexible material. Used in clothing (e.g. jackets and jeans), luggage and other bags, camping ...

Standards & traceability

ASME B18 standards on certain fasteners

The American Society of Mechanical Engineers (

ASME The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing ...

) publishes several Standards on fasteners. Some are: * B18.3 Socket Cap, Shoulder, Set Screws, and Hex Keys (Inch Series) * B18.6.1 Wood Screws (Inch Series) * B18.6.2 Slotted Head Cap Screws, Square Head Set Screws, And Slotted Headless Set Screws (Inch Series) * B18.6.3 Machine Screws, Tapping Screws, and Metallic Drive Screws (Inch Series) * B18.18 Quality Assurance For Fasteners * B18.24 Part Identifying Number (PIN) Code System Standard for B18 Fastener Products

For military hardware

American screws, bolts, and nuts were historically not fully interchangeable with their British counterparts, and therefore would not fit British equipment properly. This, in part, helped lead to the development of numerous

United States Military Standard A United States defense standard, often called a military standard, "MIL-STD", "MIL-SPEC", or (informally) "MilSpecs", is used to help achieve standardization objectives by the U.S. Department of Defense. Standardization is beneficial in achievi ...

s and specifications for the manufacturing of essentially any piece of equipment that is used for military or defense purposes, including fasteners. World War II was a significant factor in this change. A key component of most military standards is

traceability Traceability is the capability to trace something. In some cases, it is interpreted as the ability to verify the history, location, or application of an item by means of documented recorded identification. Other common definitions include the capab ...

. Put simply, hardware manufacturers must be able to trace their materials to their source, and provide traceability for their parts going into the supply chain, usually via bar codes or similar methods. This traceability is intended to help ensure that the right parts are used and that quality standards are met in each step of the manufacturing process; additionally, substandard parts can traced back to their source.