Understanding the Different Types of Fasteners and Their Use Cases
Understanding all types of fasteners and their use cases is an undertaking that will take a great deal of learning before you can claim mastery.
If you’re looking to keep up to date with the latest fasteners or need a handy reference guide, you’ve come to the right place.
Permanent or Temporary — What’s the Difference?
There are two key categories under which all fasteners fall — permanent and temporary.
Permanent fasteners are single-use, intended to join two materials and — as the name suggests — can’t be removed once installed. Permanent fasteners are used widely throughout many industries, including automotive and consumer electronics. Examples of common permanent fasteners include rivets, nails or welds.
Temporary fasteners are designed specifically to join two materials or objects, with the option to be removed and reused without damaging the objects they hold together. Common examples include bolts, screws, nuts, washers and studs.
Types of Fasteners
Broadly speaking, fasteners can also be categorised in an entirely different way, including but not limited to the following:
- Externally-threaded: Bolts, screws and studs identified by their external thread profile.
- Nuts: Combined with a bolt, used to assemble multiple components together.
- Washers: Used with nuts and bolts, washers help better distribute the force load for durability.
- Rivets: A permanent fastening solution that joins larger, flatter materials such as metal sheets.
Externally Threaded Fasteners
Threaded fasteners are one of the most common fastener types, used in all projects across all industries. Threaded fasteners include components such as bolts, screws and studs.
Bolts are typically used with nuts and sometimes a washer to create a long-lasting but temporary fastening that can be uninstalled as required. The tightening of the nut on the bolt creates friction and holds the fastener in place by creating a clamp load.
Screws work much in the same way as a bolt, with one key difference. Instead of using a nut, they utilise an internally threaded hole. Screws come in various shapes and sizes, such as machine screws, self-tapping screws and grub screws. Again, screws are typically classed as a temporary fastener that can be uninstalled.
Studs are slightly different — they don’t have a head and are threaded on each side. Studs are typically used to join two materials via internal threads on each component.
Threaded fasteners work well in many situations but are prone to breaking or loosening in assemblies subjected to cyclic loadings, such as vibrations.
As previously mentioned, nuts are commonly used with bolts to clamp the two materials together. Hexagonal nuts are the most common. However, there are also lock nuts, shear nuts and wing nuts.
Hexagonal nuts are used in various assemblies and have multiple use cases. These nuts will utilise the object to create friction, keeping them sturdy.
Lock nuts, as the name suggests, are ideal when the nut needs to lock without using an object for friction. Again, these can be used in various assemblies across industries.
Wing nuts are commonly used in assemblies whereby they need to be removed often. The head of the nut has a winged shape, hence the name, which means it can be removed and installed manually.
Commonly used in conjunction with a bolt and nut, a washer is used to maximise the bearing area in an assembly and provide more torque while protecting the fastened object. There are several washer types, each with its own use case.
Flat washers are perhaps the most common. These types of washers evenly distribute the load during the tightening process. Flat washers are used in many industries and assembly types.
Spring washers provide a locking mechanism that prevents the bolt from vibrating loose on assemblies prone to vibration or cyclic loading. The spring-loaded design means they can withstand more pressure than a flat washer.
Cup washers utilise a curved design in which the head of the bolt or screw can fit to create a flush finish. These are commonly used in assemblies that involve wood.
Repair washers are similar to a flat washer, although they have a larger diameter, so the load is spread wider, reducing the chance of damage to the object being fastened. They're ideal in use cases whereby the material of the assembly is prone to damage.
Rivets are a permanent fastener that can’t be removed — at least not without a high risk of damaging the fastened materials. Although used across many industries, rivets are commonly used to join metal sheets or plates. Of course, there are multiple rivet types.
Solid rivets are perhaps the most common, consisting of a solid shaft and a head on one side. The shaft of the rivet inserts into a pre-drilled hole. The side without a head is then deformed using a rivet gun to create a solid fastening. These are used in situations whereby safety and reliability are paramount.
Also known as pop rivets, blind rivets are used in metal fixing applications where the assembly's access to the rear side — the ‘blind’ side — is limited. A blind rivet consists of two parts, the body and the mandrel, and can be inserted through a drilled hole and fixed into place using a pop rivet gun.
Tubular rivets are similar to solid rivets, except the shaft of the rivet is hollowed out. These types of rivets are commonly used in commercial applications and manufacturers will often cold form the hollow part of the fastener, which means the material needs to be ductile and low strength.
The Role of Self-Clinching Technology
As previously mentioned, there are various subcategories for each fastener type, one of which is self-clinching. Self-clinching fasteners are any device that, when pressed into metal, displaces the host materials around the mounting hole, causing it to cold flow into a specially designed annual recess.
Self-clinching fasteners offer a variety of advantages:
- Strong threads or attachment in metal as thin as 0.20 mm/.008″.
- May be installed using any parallel acting squeezing force.
- Provide high pushout and torque-out resistance.
- Don’t require special hole preparation, such as chamfering and deburring.
- Reverse side of the metal sheet remains flush — no swaged rim protrusion.
- No retapping is necessary after application.
- Low installation costs.
Self-clinching fasteners are generally advised in assemblies where good pullout and torque loads are required. An example is sheet metal that’s too thin to provide a secure fastening using any other method. Self-clinching fasteners are ideal whenever a component needs to be readily disassembled, but ‘loose’ nuts or hardware wouldn’t be accessible.
With a compact design and low profile, self-clinching fasteners also provide a neater appearance once installed.
With so many fastener options available, it can be difficult to know where to start. The fasteners you need will depend on your project, the materials used and the desired performance.
Looking for More Specific Advice?
There are a vast amount of fasteners, variations and use cases. If you’re looking for more specific advice, download our helpful guide. Alternatively, our team of technical fastener experts are on hand to help with:
- Technical fastener questions and consultations.
- Review drawings and 3D models.
- Technical cleanliness needs.
- Explore product teardown opportunities.