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 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, or alloy steel. Other alternative methods of joining materials include: crimping, welding,

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, gluing,

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 may also be used, such as with magnets,

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 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 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, 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, 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 ...

, nut and bolt, possibly involving washers. 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 *

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 * brass fastener * buckle * button * cable tie * cam * captive fastener * clamp (or cramp) ** hose clamp * clasp and shackle ** bolt snap ** carabiner ** 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 **

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 * 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 * hook-and-eye closure * hook and loop fastener ** Velcro * latch * nail 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 ** tent peg *

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 ** dowel ** linchpin ** R-clip ** safety pin ** split pin **

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 * rubber band (or bands of other materials) * screw anchor * snap fastener *

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 *

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 * 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

Standards & traceability

ASME B18 standards on certain fasteners

The American Society of Mechanical Engineers ( ASME) 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 Standards 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. 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.