Fastener

A fastener is a hardware device that mechanically joins or positions two or more objects. Fasteners are typically removed and re-installed, enabling disassembly for maintenance or alteration.

Common types include screws, bolts and nuts, rivets, nails, pins, clips, washers, and anchors. Screws and bolts convert rotational motion into clamping force; bolts are used with nuts; screws thread into the material. Nails rely on driven friction to secure. Rivets permanently fasten by deforming their tail. Pins and cotter pins provide alignment or temporary retention. Washers distribute load and prevent pull-through; anchors secure components to base materials like concrete or wood.

Materials and finishes: steel is most common; stainless steel resists corrosion; aluminum and brass for lighter loads; plastic or composite fasteners for non-conductive or chemical resistance. Finishes such as zinc plating, hot-dip galvanizing, or electroplating improve corrosion resistance.

Standards and design: Fasteners come in standardized thread forms and sizes (for example ISO metric threads, Unified Thread Standard). Selection depends on load type (shear vs tensile), material compatibility, and environment. Preload, thread engagement, and installation torque are critical for performance; some assemblies use locking features such as thread-locking compounds or nuts with captive washers.

Usage and maintenance: proper installation tools and procedures are essential. Inspect for corrosion, wear, or loosening and replace as needed. In critical applications, fastener performance is verified through testing and inspection.