A beginner's guide to fasteners: nuts, bolts, screws, and washers
A fastener is a hardware device used to mechanically join or affix two or more components. They’re essential in construction, automotive, manufacturing, and DIY projects.
This guide breaks down the four most common types: bolts, screws, nuts, and washers. See our wider range online or via our catalogue.
1. Bolts
Bolts are externally threaded fasteners designed to be used with a nut. They require a pre-drilled hole and are typically used where strong, long-lasting connections are needed.
Common bolt types:
- Hex bolts: Most common for structural and mechanical use
- Socket head bolts: Used in machinery or tight spaces
- Cup head bolts: Rounded head, used in timber and metal
Tip: Match the bolt with the correct nut and washer for optimal performance.
2. Screws
Screws differ from bolts in that they usually create their own thread when driven into material.
Common screw types:
- Self-drilling screws: Ideal for drilling into steel
- Wood screws: Coarse thread, ideal for timber
- Self-tapping screws: Cut their own thread in metal or plastic
- Machine screws: Used with pre-tapped holes or nuts
Tip: Choose the correct driver head (Phillips, slotted, hex) to avoid stripping.
3. Nuts
Nuts are internally threaded fasteners used in conjunction with bolts. When tightened together, they provide strong clamping force.
Common nut types:
- Hex nuts: Standard six-sided nut
- Nyloc nuts: Feature a nylon insert to prevent loosening
- Flange nuts: Have a built-in washer for greater surface area
Tip: Always use the same thread pitch and diameter as the bolt.
4. Washers
Washers are thin plates used to distribute the load of a fastener, reduce friction, or prevent loosening.
Common washer types:
- Flat washers: Spread load over a larger area
- Spring washers: Prevent loosening due to vibration
- Sealing washers: Provide a watertight seal (e.g. neoprene or rubber)
Tip: Use a washer to protect the surface of your workpiece.
How to choose the right fastener
Consider the following:
- Material compatibility (e.g. stainless steel for outdoor use)
- Load requirements (strength, shear, tension)
- Thread type and size
- Environmental exposure (e.g. galvanised for corrosion resistance)
If in doubt, our team is here to help.
Explore fasteners with United Fasteners
Whether you’re starting a home project or sourcing for a large build, United Fasteners offers expert guidance and a wide product range:
- Bolts, nuts, screws, washers, construction and anchoring, and industrial supplies
- Over 75,000 SKUs
- Same-day delivery available
New to fasteners? Explore our wider range online or via our catalogue. For more information see our other insight articles along with our helpful technical information downloads.