Understanding the various types of fasteners

Today we’ll be going in-depth on the various types of fasteners used in industries. Fasteners are known to be devices that are used for creating a strong joint in different applications. Most fasteners allow joints to be dismantled or removed without damaging the joined parts while some are permanently joined.

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Types of fasteners

Metal fasteners are of two kinds; permanent and non-permanent bond. The permanent bonds cannot be dismantled when joined except the fastener will be destroyed and cannot be reused. On the other hand, non-permanent fasteners can be removed and reused as required. Below are the various types of fasteners and their functions.


Below are the various types of bolts

Carriage bolts – are also known as a coach bolt, having a domed or countersunk head. A square section beneath the head grips into the material, preventing the bolt from turning when the nut is tightened.

Hex head bolts – are the most common types of bolts, having hexagonal heads and are driven with a wrench. Hex tap bolts, hex cap screw, trim head hex cap screws, and hex serrated flange bolts are hex head bolts.

Machine screws – these types of bolts are screw or bolt with flat points, having a variety of drive types and heads. They are often driven into tapped holes used along with nuts and washers. Machine screws are also known as stove bolts or stovers.

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Shoulder bolts – are also known as stripper bolts or shoulder screws. They are machine screws with a shoulder between the thread of the screw and the head of the part. The non-threaded portion in this bolt extends out of the surface of the application, making it act as dowels or shafts for moving parts.

Socket cap screws – are available in button socket, button flange socket head, flat socket, and socket cap. The term socket head cap screw typically refers to a type of threaded fastener whose head diameter is normally 1.5 times or more than that of a screw shank diameter.

Socket set “Grub” screws – these types of fasteners are fully threaded and have no head. It is driven into material using an internal wrenching drive known as hex Allen key.

Squarehead bolts – similar to hex cap screws but have 4-sided head. This allows a wrench to grip more easily onto the head of the bolt. This head also provides a larger gripping area as compared to a standard 6-sided hexagonal head.

diagram of the various types of bolts

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Below are the various types of screws:

Deck screws – are easily installed in wood and composite deck materials. Their stripping effect can be eliminated with a bugle head and squarer drive.

Hex lag screws – these types of fasteners are also called lag bolts. Their head has an external hex and is driven with a wrench, used for lagging together lumber for frame, machinery to wood floors, and other heavy-duty applications.

Self-drilling screws – are types of screws having sheet metal thread with a self-driller cutting point to pierce through 20- to 14-gauge metals.

Sheet metal screws – have sharp cutting threads that cut through sheet metals, plastics, or woods. They have a fully threaded shank and sometimes have a notched point at the tip which helps to remove the chip during the process.

Wood screws – are types of screws partially threaded with large cutting threads and a smooth shank. They are designed to slide through the top piece of wood and tightly pull all boards together.

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Below are the various types of nuts:

Cap nuts – also known as acorn nuts due to their shape. it has a domed top to prevent contact with the external thread.

Castle nuts – are types of nuts used with cotter pins to prevent loosening. It is also called a castellated or slotted nut. It is used in low-torque applications, for instance, holding a wheel bearing in place.

Coupling nuts – are threaded fasteners types used for joining two male threads, most commonly threaded rod. A wrench can be used to drive them nuts because their outside is a hex.

Flange serrated nuts – have a wide flange at one end acting as an integrated washer that does not move or spin. This serrated flange distributes the pressure of the nut over the part being secured. It also creates a locking action to prevent loosening.

Hex finish nuts – are types of fasteners used for fastening to a hex cap screw, socket cap screw, or bolt. They are also driven with a wrench.

Hex jam nuts – are used when locking in place is required without clamping to another object. These types of nuts are hex shape with internal threads, but they are thinner than hex finish nuts.

Heavy hex nuts – are heavier, thicker, and larger than normal hex nuts. They are internally threaded with hex-shaped, often used with hex cap screws and carriage bolts.

Hex machine nuts – are hex-shaped with internal threads. They are smaller than a hex jam or hex finish nut, used with machine screws under 1/4” diameter.

Hex machine nuts small pattern – is also hex-shaped with internal threads, smaller than a hex jam or hex finish nut.

Keps-K lock nuts – are also known as keps nut, k-nuts, or washers nuts. These types of fasteners have an attached free-spinning lock washer.  They are designed to make assembly more convenient.

Knurled thumb nuts – has a knurled outside surface instead of hex, which can be tightened by hand. It is often used as decorative finishes or applications.

Nylon hex jam nuts – are low-profile lock nut hex-shaped, internally threaded with a nylon insert. The nylon material prevents loosening from vibration and cross threads to stop the nut from backing off of the fastener.

Nylon insert lock nuts – these types of fasteners are hex-shaped and are internally threaded with a nylon insert. This nylon material prevents loosening from vibration and cross threads to stop the nut from backing off the fastener.

Prevailing torque lock nuts (stover) – these types of nuts are chamfered in their corners and have a conical top. The distortion at the top threads’ resists loosening from vibration. They are also called one-way nuts, that is, they can only be installed one way. Stovers are often used in high-temperature applications because there is no nylon insert, all its body is metal.

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Diagram of nuts:

diagram of the various types of nut

Slotted hex nuts – these nuts types are with a portion cut out in order to be used with a cotter ping to create a locking mechanism. These nuts are much similar to a castle nut, only that they have a lower profile which sometimes makes them a better option.

Square nuts – are types of fasteners with four sides and may be flat or beveled at the top. They offer a greater surface contact area, which makes them more resistant to loosening.

Structural heavy hex nuts – are comparable to finish nuts but are designed to be stronger and thicker. They are often used in steel-to-steel structural connections.

T-nuts – are used to fasten wood, particle, or composite board leaving a flush surface. T-nuts often have 3 or 4 prongs that enter the surface providing better retention.

Breakaway or shear nuts – are cone nuts with a hexagonal gripping point, designed with an intentional flaw to snap the hexagonal head off once the maximum torque is reached.

Tri-groove nuts – have a tapered diameter making them inevitable to grip with grabbing devices like adjustable wrenches or pliers. A special unconventional gripping device to install them making them more secure than a typical nut.

Wingnuts – are types of threaded fasteners with wings on each side of the body allowing for manual turning and installation. They are used on applications where the nut will be often removed, which is why it can be easily loose and tight by hand.

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Below are the various types of washers:

Backup rivet washers – are used to create a larger install diameter, which gives the rivet a better hold and support. These types of washers help to prevent the pull-through of rivets.

Belleville conical washers – are types of washers that add extra tension to a joint assembly. They are used in stacks to increase the load, deflection. These fasteners types are also considered lock washers since they add tension and can absorb vibration from the assembly.

Dock washers – are heavy-duty washers, used often in docks building. They are also used in heavy-duty construction that requires thick washers. Well, dock washers are similar to fender washers with a small inside diameter hole.

Fender washers – are round washers with small inside diameter holes. They are used to prevent pull-through and provide a greater bearing surface under the fastener.

Extra thick fender washers – are also round washers with a small inside diameter hole, just that the thickness of the washer is more than the standard fender washers. They are used to prevent pull-through and offer a greater bearing surface under the fastener.

Finishing cup washer – these types of fasteners are in form of a cup so that the head of the screw or fastener can fit in. They create a finish flush with the top of the head. This is why they are used for finishing.

NAS washer – is a round washer with a smaller inner and outer diameter. It is often used in military applications due to its strict measurement specifications.

Neoprene EPDM washer – is also a round washer that is slightly beveled with a neoprene lining. It is often used with sharp points and self-drilling TEK screws to make a watertight seal around the screw or metal roofing or siding.

Structural washer – is thick and strong, used for heavy-duty applications. This washer is used in steel beams and girder fastener assemblies.

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Diagram of washers:

diagram of the various types of washers

Square washer – has a square shape and may be flat on both sides or one on the side and beveled on one side. This washer is often used with square head bolts. It prevents pull-through and provides a larger surface area and greater hold than standard round flat washers.

Flat washers – have round outer diameter thin plates containing a punched center hole that let the bolt or screw in. these washers are used to distribute loads of threaded bolts, screws, and nuts evenly as the fastener is tightened.

Extra thick flat washers – are thicker than the standard flat washers. They have round outer diameter thin plates with a center hole punched to the size of the bolt or screw.

Military standard flat washers – are types of fasteners that undergo extensive inspection for chemical, physical and dimensional qualities. MS washer types must meet specific inner diameter and outer diameter specifications.

900 series flat washers – are round and thinner than a standard flat washer with a smaller inside and outside diameter.

Split ring lock washers – are types of washers used to prevent nuts, bolts, and screws from vibrating loose. These washers are rings that are split at one point and bent into a helical shape.

High collar lock washers – are designed to fit under the head of a socket cap screw. They are also used to prevent nuts, bolts, and screws from vibrating loose. These washers are rings that are split at one point and bent into a helical shape.

External tooth lock washer – is used for locking and tensioning. This washer is round with teeth on its outside, making it hold maximum power. It must be used with a fastener with adequate head diameter.

Internal tooth lock washer – is a round washer with internal teeth, designed to prevent a nut or screw head from loosening with the struct action created by the teeth. It is used for locking and tensioning.

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Below are the various types of rivets:

Pop rivets (open end) – are known as blind rivets, used to connect two pieces of material in a quick, efficient way. These rivets are tubular, having hats and mandrels.

Closed-end pop rivets (sealed) – differs from a standard blind pop rivet because they feature a closed-end which creates a watertight seal.

Large flange pop rivets – are types of fasteners called oversize pop rivets having larger washers on the hat than a standard pop rivet. They are also known as blind rivets used for connecting two pieces of material in a quick, efficient way.

Countersunk pop rivets – also known as flat pop rivets, used for connecting two pieces of material with ease, quick and efficient way. The rivets are tubular, comprising of hat and mandrel. The mandrel’s length is snapped off when installed.

Colored rivets – are types of rivets having their hat painted either brown, black, or white. The color helps to hide the rivets and create a finished look. It also makes the rivets extra visual by using the opposing color from the installation material.

Multi-grip rivets – are types of rivets used in substitution of conventional rivets where the thickness of installation materials varies. These rivets can simply expand to the size (within its range) and hold the material together.

Structural rivets – are used to create a stronger assembly than normal stainless-steel pop rivets. They create an intense amount of force and a different tool is required to install the fasteners.

Tri-fold rivets – are types of rivets also called exploding rivets, having three cuts in the hat that causes the hat to fold outward when installed into three distinct wings. These rivets types offer better strength and holding power than standard pop rivets.

types of rivets

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Below are the various types of inserts:

Dowel pins – are cylindrical with slightly beveled ends, manufactured on pneumatic dowel equipment. They come in pre-cut length and diameters and are used in many applications. Industries like aerospace also make good use of dowel pins. These pins are used in joint reinforcement, shelf support, furniture build. Hobbyists use them to build toys and models.

Helicoil threaded inserts – are precision-formed screw thread coils in a diamond shape and wound into a spiral coil. It is installed into Helicoil tapped holes. These types of inserts offer permanent conventional 60-degree internal screw threads. These inserts are larger in diameter prior to installation.

E-Z Lok threaded inserts – requires special drilling, unlike Helicoil. They are used for metal using standard tools. Stainless steel threaded inserts are used for metal applications, and brass types are used for wood and soft material applications.

Keystock – is a solid rectangular-shaped solid bar stock. It is often machined into a machine key, serving as a wedge.

Threaded rod – is threaded with no head, available in many grades and materials. They are used for fastening anything from anchor bolt, to suspending electrical or plumbing equipment from a ceiling.

Unthreaded rods – are also called a round rod, used in framework, shafts, braces, supports, and axles.


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Retaining rings

Below are the various types of retaining rings:

Bowed-e retaining rings – are designed to be installed into a groove on a shaft. The clips exert force to the material once snapped into the groove or preload on retained parts in order to compensate for accumulated tolerances.

e-style retaining rings – are types of retaining rings designed to use the style of the radial retaining ring. They are called e-rings because of the three prongs on the inside of the shaft which make contact with the bottom of a groove. The groove on a shaft creates a shoulder for effective assembly retention.

External shaft retaining rings – are designed to be used in a groove or shaft. A portion of the retaining rings protrudes from the groove in order to create a shoulder to keep an assembly. This occurs once installed in a groove on a shaft.

Internal housing retaining rings – are designed to be also used in a groove on a shaft. It is installed in a bore or housing, a portion of these retaining rings protrude from the groove in order to create a shoulder to keep an assembly.

retaining rings

Concrete anchors

Below are the various types of anchors:

Acoustical wedge anchors – are types of fasteners used to anchor and secured suspended wire to solid or hollow masonry materials. The fasteners are inserted into a pre-drilled hole and then struck with a hammer.

Drop-in anchors – are internally threaded anchors that are installed overhead and flush with the surface of the concrete. These types of fasteners are used to create handrails, lighting fixtures, and many other fixtures.

Double expansion shield anchors – are designed for softer material installation or that of low quality. Their entire length expands in the hole to create a very secure hold. The expansion maximizes friction and holds on to the installation material.

Hammer drive pin anchors – are used for lighter loads than other types of concrete anchors. Drive pins apply fixtures to masonry materials. Hammers are used to driving the exposed head of the pin, which expands the base inside of the masonry material creating a hold.

Kaptoggle hollow wall anchors – are installed through a hole in walls or block. It securely holds to the wall as a machine screw is used. These types of fasteners are proven to have better holding power than conventional types.

Lag shield expansion anchors – are shielded expansion anchors used to hold lag screws. They expand outwards as lag screws are driven into them. This expansion press against the installation surface creates a tight and secure hold. These types of fasteners also have very precise internal threading to allow the installation lag bolt to turn easily.

Machine screw anchors – are types of anchors installed into masonry materials in a pre-drilled hole. They are placed inside the hole and a machine screw is threaded into the anchor and tightened. A coned portion is pulled into the sleeve causing it to deform. This deformation of the sleeve results in a tight wedge inside the hole that cannot be removed easily.

Diagram of anchors:various types of anchors

Masonry screws – are also known as Tapcons, cut threads into concrete, brick, or block when installed. These screws have extended corrosion protection is gained from the blue climaseal coating. No hole spotting or insets is needed here.

Plastic toggle anchors – are types of fasteners used in hollow walls or cinder blocks to create a fastening point for sheet metal screws. These types of anchors have legs that fold to enter a pre-drilled hole that expand when a screw is driven into them. As soon as the legs fully expanded, the toggle anchor is securely in place.

Sammy screws – these screws are used with threaded rods and save time by drilling into masonry materials. They feature a female threaded portion to accept the threaded rod into it. These screws are installed vertically or horizontally. They are commonly employed due to their lower installation costs, flexibility, and ease of use.

Sleeve anchors – consist of a threaded stud with an outwardly flared cone-shaped end, with a nut and washer on the end. The stud is pulled into the expander sleeve as the nut is tightened. This wedge outwards and locks the anchor into the base material.

Toggle wing hollow wall anchors – are used when installing through materials. The wing can be bent in haft and pushed through the material. Once it finds its way through the material, it expands and a screw will be used to hold it in place against the rear side of the material.

Wedge anchors – are used to anchoring and secure materials and equipment to solid concrete masonry surfaces. These types of anchors consist of anchors, nuts, and washers. They are used to fasten concrete to equipment, materials, motors pipe, strut, plastics, wood, and generators.


That is all for this article, where we explained the various types of fasteners which include bolts, nuts, screws, washers, rivets, etc.

I hope you get a lot from this post, if so, kindly share with other students. Thanks for reading, see you next time!

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