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 b ...

is an example of creating permanent joints. Steel fasteners are usually made of

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 r ...

carbon steel Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: * no minimum content is specified or required for chromium, coba ...

, 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 b ...

soldering Soldering (; ) is a process in which two or more items are joined by melting and putting a filler metal ( solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not inv ...

brazing Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal. Brazing differs from ...

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 mixe ...

, or the use of other adhesives.

Force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a ...

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 ...

vacuum A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or " void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often ...

(like

suction cups A suction cup, also known as a sucker, is a device or object that uses the negative fluid pressure of air or water to adhere to nonporous surfaces, creating a partial vacuum. Suction cups are peripheral traits of some animals such as octopuses ...

), 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 Joinery is a part of woodworking that involves joining pieces of wood, engineered lumber, or synthetic substitutes (such as laminate), to produce more complex items. Some woodworking joints employ mechanical fasteners, bindings, or adhesives, ...

make use of separate internal reinforcements, such as

dowel A dowel is a cylindrical rod, usually made of wood, plastic, or metal. In its original manufactured form, a dowel is called a ''dowel rod''. Dowel rods are often cut into short lengths called dowel pins. Dowels are commonly used as structural ...

s or

biscuits A biscuit is a flour-based baked and shaped food product. In most countries biscuits are typically hard, flat, and unleavened. They are usually sweet and may be made with sugar, chocolate, icing, jam, ginger, or cinnamon. They can also be ...

, 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 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 A bread clip is a device used to hold plastic bags closed, such as those in which sliced bread is commonly packaged. They are also commonly called bread tags, bread tabs, bread ties, bread buckles, or bread-bag clips. By sealing a bag more secure ...

. 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 similarl ...

, 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 co ...

, cable,

chain A chain is a serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression but linear, rigid, and load-bearing in tension. ...

, or

plastic wrap Plastic wrap, cling film, Saran wrap, cling wrap, Glad wrap or food wrap is a thin plastic film typically used for sealing food items in containers to keep them fresh over a longer period of time. Plastic wrap, typically sold on rolls in boxes ...

may be used to mechanically join objects; but are not generally categorized as fasteners because they have additional common uses. Likewise,

hinge A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation: all other ...

s 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 thread A screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called ...

s. 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 ...

, 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,

threaded insert A threaded insert, also known as a threaded bushing, is a fastener element that is inserted into an object to add a threaded hole. They may be used to repair a stripped threaded hole, provide a durable threaded hole in a soft material, place a thr ...

s, and threaded rods. Other types of fastener include: *

anchor bolt Anchor bolts are used to connect structural and non-structural elements to concrete.. The connection can be made by a variety of different components: anchor bolts (also named fasteners), steel plates, or stiffeners. Anchor bolts transfer diff ...

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) A bolt is a form of threaded fastener with an external male thread requiring a matching pre-formed female thread such as a nut. Bolts are very closely related to screws. Bolts vs. screws The distinction between a bolt and a screw is poo ...

bolt snap A bolt snap is a type of snap hook with a manually operated bolt action slide gate of medium security used to clip a light load to a ring, eye, loop or bight to temporarily secure or suspend an object. They are used for a wide variety of applica ...

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 A shackle (or shacklebolt), also known as a gyve, is a U-shaped piece of metal secured with a clevis pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism. The term also applies to handcuff ...

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 * cleco * clip **

circlip A circlip (a portmanteau of "circle" and "clip"), also known as a C-clip, Rotor Clip, snap ring or Jesus clip, is a type of fastener or retaining ring consisting of a semi-flexible metal ring with open ends which can be snapped into place, int ...

** 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 A Terry clip (or Terry's clip) is a spring metal clip used to hold a cylindrical object. For example, to secure a bicycle pump onto a bicycle frame. The object to be held is pushed into the clip to secure it, and pulled out to release. The original ...

clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

* drawing pin (thumbtack) *

flange A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of an iron beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer of ...

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

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 PEM or Pem may refer to: People * Pem Sluijter (1939–2007), Dutch poet Science * Photoelastic modulator * Polyelectrolyte multilayer * Positron emission mammography * Proton exchange membrane, semipermeable Engineering * Plastic encapsulated ...

* pins **

clevis fastener A clevis fastener is a two-piece fastener system consisting of a ''clevis'' and a ''clevis pin head''. The clevis is a U-shaped piece that has holes at the end of the prongs to accept the clevis pin. The clevis pin is similar to a bolt, but is ...

** cotter **

** linchpin ** R-clip ** safety pin **

split pin A split pin, also known in the United States of America as a cotter pin or cotter key, is a metal fastener with two tines that are bent during installation, similar to a staple or rivet. Typically made of thick wire with a half-circular cross ...

spring pin A spring pin (also called tension pin or roll pin) is a mechanical fastener that secures the position of two or more parts of a machine relative to each other. Spring pins have a body diameter which is larger than the hole diameter, and a chamfer ...

** tapered pin *

retaining ring A retaining ring is a fastener that holds components or assemblies onto a shaft or in a housing/bore when installed - typically in a groove - for one time use only. Once installed, the exposed portion acts as a shoulder which retains the spec ...

s **

** e-ring * rivet-like **

well nut A well nut is a blind rivet-like type of fastener used to blindly fasten a piece (much like a molly bolt) and to seal the bolt hole. They are often referred to by the proprietary name Rawlnut or Rawl nut, the name by which they are known in the ...

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 A snap-fit is an assembly method used to attach flexible parts, usually plastic, to form the final product by pushing the parts' interlocking components together. There are a number of variations in snap-fits, including cantilever, torsional and ann ...

* staple * stitches *

strap A strap, sometimes also called strop, is an elongated flap or ribbon, usually of leather or other flexible materials. Thin straps are used as part of clothing or baggage, or bedding such as a sleeping bag. See for example spaghetti strap, ...

tie Tie has two principal meanings: * Tie (draw), a finish to a competition with identical results, particularly sports * Necktie, a long piece of cloth worn around the neck or shoulders Tie or TIE may also refer to: Engineering and technology * ...

* toggle bolt *

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 Twist may refer to: In arts and entertainment Film, television, and stage * ''Twist'' (2003 film), a 2003 independent film loosely based on Charles Dickens's novel ''Oliver Twist'' * ''Twist'' (2021 film), a 2021 modern rendition of ''Olive ...

wedge anchor Anchor bolts are used to connect structural and non-structural elements to concrete.. The connection can be made by a variety of different components: anchor bolts (also named fasteners), steel plates, or stiffeners. Anchor bolts transfer diffe ...

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 In commerce, a supply chain is a network of facilities that procure raw materials, transform them into intermediate goods and then final products to customers through a distribution system. It refers to the network of organizations, people, activ ...

, 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.