- Published 25 Apr 2024
- Last Modified 25 Apr 2024
- 11 min
Guide to Fasteners
Seeking answers about the different types of fasteners, their uses, and applications? Our detailed guide to fasteners can help.
Reviewed by David Carmichael, Solution Engineer (March 2024)
In this guide, we delve into what fasteners are, the variety of fasteners available, and how to choose the right one for your specific needs. Whether you're in engineering, construction, or manufacturing, understanding fasteners is paramount to any project.
Let's delve deeper into the world of fasteners and find the best solution for your task.
What are Fasteners?
Fasteners are a broad range of key components used to securely join or fasten two or more objects together. They are available in a multitude of shapes, sizes, and materials, each designed to serve a unique purpose. From screws and bolts to nuts and washers, the range of fasteners is vast and largely depends on your application.
Fasteners play a pivotal role in many industries. Their usage spans construction, manufacturing, automotive, electrical installations, machinery assembly, and even everyday applications. Fasteners maintain the integrity, stability, and longevity of structures, equipment, and products. They ensure components remain securely connected and can withstand external forces such as vibrations, tension, or shear. Without fasteners, assemblies could fail, leading to expensive repairs, safety hazards, or production delays.
Types of Fasteners
There are various types of fasteners available to cater for different applications. In this section, we will explore some of the most common fasteners and their uses.
Rivets and Nails
Rivets and nails are used to permanently join materials together. They provide a strong and reliable connection. Rivets are typically metal and require a rivet gun for installation whereas nails are driven into place with a hammer.
Girder Fixings
Girder fixings are robust fasteners designed for securing girders and beams. They provide sturdy and reliable connections, ensuring structural integrity.
Magnets
Magnets are unique fasteners that operate based on magnetic fields. They are used in various applications, including the industrial, automotive, and electronic sectors.
How Do Magnets Work?
Magnets work based on the principles of electromagnetism. At the atomic level, magnets are made up of many atoms, with electrons orbiting the nucleus. Electrons have a property called spin, which gives them a magnetic moment, making them act like tiny magnets.
In magnetic materials, the magnetic moments of a significant number of electrons align in the same direction due to the atomic structure of the material. This alignment creates a magnetic field.
The magnetic field flows from the magnet's north pole to its south pole, creating a loop. When two magnets are brought close to each other, their magnetic fields interact. If opposite poles face each other, they attract; if the same poles face each other, they repel. This interaction is the basis of how magnets work.
What are Magnets Made of?
There are several types of magnets, made of different materials:
- Ferromagnetic Materials: These are the most common materials used for permanent magnets. They include iron, nickel, cobalt, and some alloys
- Rare Earth Magnets: These are strong permanent magnets made from alloys of rare earth elements. The most common types are neodymium magnets (NdFeB) and samarium-cobalt magnets (SmCo)
- Alnico Magnets: Made from aluminium, nickel, and cobalt, alnico magnets are known for their strong magnetic fields and high resistance to demagnetisation. They are commonly used in sensors, motors, and loudspeakers
- Ceramic or Ferrite Magnets: These are made from ceramic materials, specifically ferric oxide mixed with strontium or barium carbonate. While not as strong as neodymium magnets, ceramic magnets are inexpensive and offer good resistance to corrosion and demagnetisation
- Flexible Magnets: Made from ferrite powder and rubber polymer resin, these magnets are easy to cut and shape. They are weaker than other types of magnets but are versatile and can be used in various applications, such as magnetic signs and displays
The choice of material depends on the application, considering factors like magnetic strength, resistance to demagnetisation, and temperature stability.
Nuts and Washers
Nuts and washers are essential for securing bolts and screws. Nuts are threaded fasteners used with bolts to provide a secure grip and joint. Washers distribute the load and prevent damage to the fastened material. They are ideal for applications that require frequent disassembly and come in various sizes and shapes, such as hex nuts and wing nuts.
Screws and Bolts
Screws and bolts are common types of fasteners. They are versatile and used for joining materials together or securing objects to a surface. They come in a variety of sizes, head types, and drive types. Bolts are similar to screws but are typically larger and require a nut to secure them in place. The choice of screw or bolt depends on the specific application.
Some common types of screws and bolts include:
- Hex Bolts: These partially threaded bolts are widely used in construction and machinery applications. They are tightened with a wrench and used with a nut or in a tapped hole
- Hex Set Screws: These resemble hex bolts but are fully threaded instead. Also used in machinery and construction, they can be used with a nut or in a tapped hole
- Wood Screws: These are commonly used in carpentry. Providing a strong clamping force, wood screws strengthen the joint between two materials. They can be used to fix door hardware such as locks, bolts, and hinges
- Self-Drilling and Thread-Forming Screws: When these screws are inserted, they form a thread. The choice of screw depends on the material, thickness, and application. A pilot hole may be required
- Machine Screws: These are fully threaded and used with a nut or in a tapped hole. They can be used in many applications where high-strength fasteners are not required. The drive type dictates the appropriate screwdriver required
- Socket Screws: These have an internal hex drive and are tightened using a hex key. They are used in applications with limited clearance. A headless version is available and is known as a socket set screw or a grub screw
- Carriage Bolts: Also known as coach bolts, these have a domed head with either a square underside that engages material or a square hole to prevent spinning during installation
Panel Fasteners
Panel fasteners are typically designed for working with sheet metal materials. They are ideal for applications such as assembly and metalworking.
Clips and Springs
Clips and springs provide secure fastening and can be easily attached or detached. They are commonly used in automotive, electronic, and industrial applications.
Wall Plugs
Wall plugs, also known as anchors, are used to provide a secure fixing in materials like brick, concrete, or plasterboard. They create a firm base for screws and bolts in hollow walls or masonry.
Spacers
Spacers are used to create a gap or distance between objects. They ensure proper alignment, prevent damage, and provide stability in various applications.
Choosing the Right Fastener
Choosing the right fastener involves several factors, but selecting the appropriate fastener is crucial for ensuring your project's durability and functionality.
Here are some tips to help you select the right fastener:
- Determine the specific requirements of your project, such as load capacity, environmental conditions, and material compatibility
- Consult relevant standards and guidelines to ensure compliance with industry specifications
- Consider the aesthetics of the fastener if it will be visible in the final project
- Take into account the tools and equipment available for installation
By carefully considering these factors and following the tips mentioned, you can confidently select the right fastener for your project, ensuring its success and longevity.
Fastener Materials
Fasteners can be made of many materials. Different materials offer varying levels of strength, corrosion resistance, and suitability for specific applications. Common materials include brass, nylon, and stainless steel.
- Stainless steel fasteners are ideal for external use as they are highly resistant to rust and corrosion. A2 (304) and A4 (316) are two of the most common stainless steel grades. Both offer good resistance to corrosion and withstand high and low (cryogenic) temperatures. However, A4 grades are more corrosion resistant than A2. A4 should be chosen for higher corrosive or chemical environments, as well as marine conditions
- Brass is a copper alloy which is more expensive than steel but provides better corrosion resistance. Brass fasteners are often used in marine applications and electrical and plumbing installations due to their conductivity and water resistance. They are also used in applications where a decorative finish is required
- Nylon fasteners are lightweight and non-conductive, making them suitable for high-voltage assemblies and applications requiring increased insulation resistance. They offer good value and are ideal where a corrosion-free solution is required
- Zinc plating provides a moderate level of corrosion resistance, making it suitable for indoor use in a dry environment
- The thicker zinc coating on hot-dipped galvanised steel provides better corrosion resistance, making it suitable for outdoor applications. The finish is typically dull and rough. It's also worth bearing in mind that only galvanised washers and nuts fit galvanised fasteners
- Nickel and chrome-plated steel has a smooth, polished appearance and is used where a decorative finish is desired. Nickel plating gives moderate corrosion resistance
- Alloy steel is used when high-strength fasteners are required. It is usually produced with a black oxide finish which offers minimal resistance to corrosion and so is not recommended for outdoor use
- Titanium fasteners are non-toxic and offer lightness and very high corrosion resistance which makes them ideal for applications where these attributes are vital. However, they are more expensive than other material types
Fastener Size
Another key consideration is the fastener size. Choosing the correct size ensures a secure and reliable connection. Fasteners come in a range of sizes, including diameter, length, and thread pitch. It is essential to match the fastener size to the requirements of your project. Using an undersized or oversized fastener can compromise the integrity of the connection and lead to failure.
- Measuring Diameter: The diameter is measured across the threaded portion on the outside of the thread
- Measuring Length: Countersunk fasteners are measured over the whole length. All other types are measured from below the head. Fastener length is determined from where the surface of the material is assumed to be to the end of the fastener
- Measuring Thread Pitch: Fasteners that are metric have a specific thread pitch depending on the size and thread type of fastener. Generally, thread pitch refers to the distance between threads as expressed in millimetres (measured along the fastener length). A thread pitch of 1.5, for example, means that there is 1.5mm between each thread
- Nut and Washer Sizes: Nuts and washers are sized according to the screw or bolt they fit. With metric machine threaded fasteners, the thread size indicates the required screw or bolt size
- Grades and Strengths: The fastener grade indicates the mechanical properties of the material and is stamped onto the head of a bolt or screw. A higher number indicates a stronger, harder material. So, a grade of 12.9 will be stronger than 10.9, for example. A manufacturer’s stamp may also be marked
Head Types
The different fastener head types include:
- Cheese: A cylindrical-shaped head with straight sides that sits above the material surface
- Button: Consists of a low-profile, rounded, dome-shaped head, typically with a slotted or hex socket drive
- Socket: A narrow head with a hex socket drive
- Countersunk (raised): Fastened into a countersunk hole and with an oval, raised head for decorative purposes
- Countersunk (flat): Fastened into a countersunk hole with the head sitting flush with the material surface
- Pan: Consists of a raised, domed head which sits above the material surface
- Hex: Used for larger bolts and set screws. Fastened with a spanner or socket
Drive Types
Fastener drive types include:
- Slotted: Highly versatile, most commonly used in woodworking applications
- Pozidriv: An improved version of the traditional Phillips drive, Pozidrives allow for greater torque pressure and are less likely to cam out
- Hex Socket: Used with a hex key in applications with limited space
- Torx: Very common in automotive applications and highly resistant to slippage and cam-out
- Security: A range of tamper-proof types with a spigoted recess virtually eliminating unauthorised removal
Summary
Different types of fasteners serve various purposes. Understanding these can help you choose the right fastener for your application as each type has distinct characteristics and is designed for specific applications.
At RS, we offer a wide range of fasteners to meet your needs. Whether you're looking for screws, bolts, rivets, or any other type of fastener, you can find it in our extensive selection. Browse our website to explore our range and find the right fasteners for your projects.
