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What are Fasteners: Definition, Types, Application, Materials

Table of Contents

Fasteners are indispensable components in countless applications, joining together materials with reliability and precision. As the foundation of both simple and complex assemblies, fasteners come in various forms including screws, nuts, bolts, washers, and jam nuts, playing pivotal roles in industries ranging from construction to aerospace. This article aims to demystify the world of fasteners, delineating their types, including both non-permanent threaded fasteners and permanent fasteners, as well as exploring their multifaceted applications and the diverse materials from which they are made.

Types of fasteners

Non-permanent Threaded Fasteners

A Non-Permanent Threaded Fastener is a mechanical device used to hold two or more objects together in a way that allows for their separation without causing damage to the fastener or the objects being joined. This category of fasteners typically involves threads—a helical structure used to convert between rotational and linear movement or force.

  • Screws
  • Nuts
  • Bolts
  • Washers


Screws are a common type of fastener. They are usually made of metal and have spiral-shaped raised stripes called threads that thread into objects to join parts together. Their design allows the force exerted by rotation to be converted into downward pressure, ensuring that they remain tightly anchored in the material.

Screws are designed with various heads, threads, and points, each serving a specific purpose. Here are some common types of screws based on their design:

Flat Head Screws

These are countersunk screws with a flat top. They are used when a smooth finish is required, allowing the screw to sit flush with the surface.

Flat Head Screws

Pan Head Screws

These have a rounded top and a flat underside, which offers a low profile when installed. They are commonly used in cabinetry and metalwork.

Pan Head Screws

Round Head Screws

With a dome-shaped head, these screws are not countersunk and are used where the screw head can protrude above the surface, such as in decorative hardware.

Hex Head Screws

Featuring a hexagonal head, these are driven with a wrench or socket and are often used in construction and machinery where a robust head is beneficial.

Hex Head Screws

Phillips Head Screws

Characterized by a cross-shaped recess that accepts a Phillips screwdriver, these are widely used because the design allows more torque to be applied.

Phillips Head Screws

Torx Screws

Known for their star-shaped recess, Torx screws offer improved torque transfer over Phillips head screws and are increasingly popular in the automotive and electronics industries.

Torx Screws

Set Screws

These are headless screws used to secure an object within or against another object, typically using an internal wrenching drive like an Allen or hex socket.

Set Screws


Nuts are an essential counterpart to bolts and screws, providing the necessary tension and load distribution to create secure joints. There are many types of nuts, each specialized for different applications and environments:

Hex Nuts

The most common type, with a hexagonal shape, is typically used in conjunction with a bolt or screw to fasten together multiple parts.

Hex Nuts

Lock Nuts

Designed to resist loosening under vibration and torque. Varieties include nylon insert lock nuts (nylon nuts) and those with distorted threads like the all-metal lock nuts.

Lock Nuts

Flange Nuts

These nuts have an integrated washer-like flange at one end, which provides a larger surface area to prevent damage to the material being fastened.

Flange Nuts

Wing Nuts

Known for their “wings” which allow for manual turning and tightening, making them useful in applications where frequent adjustments are needed.

Wing Nuts

Coupling Nuts

Long, hex-shaped nuts are used to connect two pieces of threaded rod or other male threaded fasteners.


Square Nuts

With a four-sided, square shape offering a larger surface area against the part being fastened, these nuts are less likely to become rounded off with repeated use.


Bolts are a type of fastener designed to secure materials together through pre-drilled holes, typically used in conjunction with nuts. They have a head on one end and threads on the other, allowing them to be tightened and released as needed, making them ideal for both temporary and permanent applications.

Hex Bolts

Characterized by a hexagonal head, these bolts are the most common type and are used in a variety of applications that require a strong fastening, often with a matching hex nut.

Hex Bolts

Carriage Bolts

Known for their smooth, rounded head and a square section underneath, which prevents the bolt from turning when the nut is tightened. They are typically used in wood connections.

Carriage Bolts

Anchor Bolts

These are embedded in concrete or masonry to provide structural support and connection to external loads. They include designs like the J-bolt and L-bolt.

As the name suggests, these bolts are shaped like the letter “U” with threaded ends on both sides. They are commonly used to support pipework or as part of a clamping system.

Eye Bolts
Featuring a loop on one end, eye bolts are used for attachment points in lifting operations or for securing cables and wires.

Tension Control Bolts (TC Bolts)
These bolts have a built-in indication for proper tensioning and are used in high-strength structural connections, often seen in steel frame construction.

Structural Bolts
Specially designed for steel-to-steel structural connections, they come in various types like A325 and A490 in the United States, with each specification designed for particular sizes and tension loads.

Flange Bolts
These have a flange under the head that acts like a washer to distribute the load. They are often used in vehicle frames and other applications where a smooth bolt head is required.

Lag Bolts (Lag Screws)
Large wood screws with a bolt head and are significantly stronger than ordinary screws. They are used to secure heavy materials like lumber or to affix items to wood.


Washers play a pivotal role in the integrity of fastening systems by evenly distributing the load of a bolt or screw over a larger area.

Flat Washers

The most basic type of washers is used to disperse the pressure of bolts or screw heads to protect the assembly surface from damage.

Flat Washers

Spring Washers

Including wave washers and lock washers, used to prevent bolts or nuts from loosening due to vibration.

Lock Washers

Designed to prevent bolts or nuts from loosening, these washers bite into the material to resist rotation when tightening force is applied.

Structural Washers

Thicker washers, often used in the building and construction industry, to withstand higher loads.

Insulating Washers

Used in electrical applications to prevent the transfer of electrical current through bolts, usually made of non-conductive materials.

Permanent Fasteners

Permanent Fasteners are fastening devices intended to create a lasting joint between two or more objects, where the connection is not meant to be readily disassembled. They typically require destructive methods for removal, such as drilling or grinding, including fasteners like welded joints, rivets, and certain adhesives.



Nails constitute the most traditional form of permanent fasteners, forged from a long history of carpentry and construction. They are designed to be driven into materials like wood or drywall, providing a quick and efficient method of joining pieces with enduring hold.

Nail Type


Common Nails

Thick and sturdy with a wide head.

Finishing Nails

Smaller head for a discreet look.

Brad Nails

Very small head, often used with a nail gun.

Roofing Nails

Short with a broad head to hold materials.

Masonry Nails

Hardened steel for penetrating stone and concrete.

Box Nails

Thinner than common nails to reduce splitting.

Duplex Nails

Double head for easy removal.


Rivets are mechanical fasteners that are particularly useful for joining metal sheets and structural components where access from only one side is possible. They provide a permanent, tamper-proof bonding and are used in a wide range of heavy-duty applications.




Anchors play a foundational role in construction, providing secure fixing points in a variety of base materials, from concrete and brick to drywall and stone. They are specifically designed to anchor fixtures into materials that might not support weight or tension using screws or nails alone.



Inserts are integral components used to enhance thread performance in materials that are otherwise unsuitable for threading, such as soft metals, plastics, and composites. They provide durable, wear-resistant threads in materials that would quickly strip under the stress of repeated use.

Fasteners: How it used

Fasteners play a pivotal role in countless applications that are essential to our daily lives.

Fasteners play a pivotal role in countless applications that are essential to our daily lives. Their omnipresence, though often unnoticed, is critical to the functionality of various devices, structures, and machinery. Here are some key applications where fasteners are not just important, but indispensable:

Automotive Industry

From the assembly of engine components with bolts and screws to the use of washers to ensure even pressure distribution and prevent leaks, fasteners are integral to building reliable and safe vehicles. Nuts and bolts must withstand high temperatures and vibrations, while inserts are often used to reinforce threading in materials that undergo regular stress.


Construction and Infrastructure

In the world of construction, bolts, and anchors secure beams and girders, while nails and screws are fundamental for woodworking and finishing details. Even in concrete structures, fasteners such as anchors and inserts are employed to affix external elements securely.


Electronics and Gadgets

The miniaturization of devices requires tiny fasteners to assemble components tightly and accurately. These include micro screws and inserts that must be precision-engineered to fit and hold together the compact and delicate parts of smartphones, laptops, and other electronic devices.


Aerospace and Defense

The demand for durability and resistance to extreme conditions makes fasteners in this sector highly specialized. Aircraft and military equipment rely on rivets for aerodynamic integrity and bolts made of advanced materials that can endure the rigors of high-speed travel and harsh environments.


Furniture and Home Appliances

Fasteners such as screws, bolts, and nuts are fundamental in assembling furniture, securing cabinets, and affixing appliances to walls or countertops. Even the jam nut, a less celebrated component, proves essential in preventing loosening from frequent use or heavy loads.


Medical Devices

Precision fasteners, including specialized screws and inserts, are used in medical devices where non-reactive and biocompatible materials are critical. They ensure the devices function reliably under strict hygiene and performance standards.

stainless steel bins

Common Materials Used for Fasteners


Steel reigns supreme as the primary material for fasteners, prized for its high tensile strength and cost-efficiency. Ideal for heavy-load applications like construction, carbon steel is common, though prone to rust, which limits its use in corrosive environments. When it comes to specific standards and specifications, such as fastener size, strength, corrosion resistance, etc., a series of standards and specifications are referenced. For example, ASTM A325, ASTM F593, and the automotive industry standard SAE J429.

Stainless Steel

Stainless steel fasteners, known for their rust resistance and durability, are indispensable in settings exposed to moisture or chemicals. While more costly, they offer longevity that often offsets the upfront investment, making them a wise choice for marine and industrial uses.

Brass, Aluminum, and Plastics

For specialty needs, brass is chosen for its low friction; aluminum for its lightweight and non-magnetic nature; and plastics for their corrosion resistance and non-conductivity, catering to specific demands in electrical, aerospace, and decorative applications.


In modern engineering, the selection of appropriate fasteners is crucial for ensuring structural integrity and longevity. The myriad types of fasteners, from the steadfast jam nut to a spectrum of screws, bolts, and nuts, demand careful selection to match the unique specifications of each manufactured part.

Start a Fastener Project Today!

EASIAHOME facility takes pride in crafting these pivotal components, ensuring that every fastener produced not only meets but exceeds the stringent standards of strength and reliability expected in modern engineering. We can provide high-quality, high-standard fasteners according to your drawings or needs.

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