Fasteners are hardware devices that mechanically join or affix two or more objects together. They are essential in countless industries, from construction and manufacturing to consumer goods. They can be temporary (allowing for disassembly) or permanent.
The main categories include:
1. Threaded Fasteners: These have threads (helical ridges) that allow them to be inserted into a threaded hole or to draw a nut toward the head.
Bolts: Used with a nut and often a washer to clamp parts together. They come in various head styles (hex, socket) and types (carriage, eye).
Screws: Typically cut their own internal thread into the material they are driven into. Types include wood screws, machine screws, sheet metal screws, and self-tapping screws.
Nuts: Used with a bolt to provide clamping force. Common types are hex nuts, lock nuts (which resist loosening), and wing nuts (for hand-tightening).
Studs: Rods that are threaded on both ends, with one end permanently fixed in a threaded hole.
2. Non-Threaded Fasteners: These rely on other mechanisms to create a joint.
Rivets: Permanent fasteners inserted into a hole and mechanically deformed (bucked) to hold parts together. Pop rivets are installed quickly from one side.
Pins: Straight, solid cylinders used to align parts or hold them in place. Types include cotter pins, dowel pins, and clevis pins.
Washers: Flat discs placed under a nut or bolt head to distribute load, prevent loosening, or act as a spacer.
Retaining Rings (Circlips): Snap into grooves to secure components onto shafts or inside housings.
3. Specialized Fasteners: This includes a wide range of purpose-built items like anchors (for masonry), inserts (for soft materials), and various quick-release fasteners.
Materials range from standard carbon steel and stainless steel to brass, aluminum, and high-strength alloys, often with coatings like zinc or chrome for corrosion resistance. The choice of fastener depends on the required strength, environmental conditions, need for disassembly, and the materials being joined.