Buyer’s Guide — SC Fastening Systems

Types of Fasteners: The Complete Guide

Bolts, screws, nuts, washers, rivets, and anchors — what each one does, and how to pick the right one.

“Fastener” is one of those words that covers a lot of ground. Understanding the different types of fasteners — what separates a bolt from a screw, or when a rivet beats an anchor — makes the difference between a joint that holds for decades and one that fails at the worst possible moment.

This guide breaks down the major types of fasteners, what each is actually built for, and how to think about choosing between them. Whether you’re specifying components for a build or just trying to figure out what’s in the bin at the hardware store, use this as your reference.

Bolts are externally threaded fasteners designed to pass through pre-drilled, unthreaded holes and pair with a nut on the other side — the nut is what actually gets tightened, not the bolt head. That makes bolts a go-to for joints that need serious clamping force and the option to be disassembled later.

• Hex bolts — the most common type, with a six-sided head sized for a standard wrench or socket
• Carriage bolts — a smooth, domed head with a square shoulder that keeps the bolt from spinning as the nut is tightened
• Anchor bolts — designed specifically to embed into concrete and secure structural elements like foundations

Screws are also externally threaded, but unlike bolts, they’re typically driven directly into a material — wood, sheet metal, plastic, or a pre-tapped hole — rather than paired with a separate nut. That makes them the workhorse fastener for framing, cabinetry, electronics, and general assembly.

• Wood screws — tapered shank designed to grip wood fibers securely
• Machine screws — precision-threaded for use with a tapped hole or nut, common in electronics and light assembly
• Self-tapping and self-drilling screws — cut their own threads as they’re driven, cutting installation time on metal and plastic

Nuts are internally threaded fasteners that pair with bolts and threaded rods to apply clamping force across an assembly. The style matters more than people expect:

• Hex nuts — the standard, wrench-driven option for general use
• Nylon-insert lock nuts — include a nylon collar that resists loosening from vibration, common in automotive and machinery
• Wing nuts — designed for hand-tightening where tools aren’t practical or frequent adjustment is needed

Washers are flat discs placed under a bolt head or nut to distribute clamping load evenly and protect the surface of the material being fastened. They look simple but do real work — skip one on a soft or uneven surface and you risk the fastener digging in, loosening, or cracking the material underneath.

• Flat washers — general-purpose load distribution
• Lock washers — use tension or teeth to resist loosening from vibration
• Fender washers — a larger diameter for soft or thin materials like sheet metal or fiberglass

Rivets create a permanent mechanical joint — there’s no disassembling one without drilling it out. A rivet is driven through aligned holes and then the protruding end is deformed (bucked or crushed) to lock both pieces together, which makes for a lightweight, high-strength joint. That’s exactly why rivets are the standard in aircraft fuselages, shipbuilding, and structural steel, where a permanent joint is a feature, not a limitation.

Anchors solve a specific problem: how do you fasten something to a material — drywall, concrete, block — that doesn’t hold threads on its own? Anchors embed into the material and provide a secure point for a screw or bolt to grip.

• Concrete anchors (wedge, sleeve, drop-in) — for heavy-duty attachment to concrete and masonry
• Drywall anchors — expand or grip behind drywall to support lighter fixtures
• Adhesive anchors — set with epoxy for high-load structural applications

Quick reference

Types of fasteners at a glance

The bottom line

Nearly every type of fastener exists to solve a specific problem — clamping force, permanence, vibration resistance, or attaching to a material that can’t hold threads on its own. Knowing which type of fastener actually fits your application is the difference between a joint that lasts and one that becomes a callback. When in doubt, match the fastener to the load, the material, and whether the joint ever needs to come apart.

FAQ

Frequently asked questions