fastenings

Fastenings are devices or methods used to join or secure two or more parts in a fixed relationship. They may be permanent or removable and are chosen based on load requirements, environmental exposure, and ease of assembly and disassembly.

Mechanical fasteners form the largest category and include threaded fasteners (bolts, screws, nuts, studs, and washers); rivets; pins; and retaining devices such as clips, clamps, and cotter pins. Threaded fasteners engage with a mating thread or tapped hole and typically require tools; rivets form a permanent joint by deforming the tail; pins provide alignment or a shear connection; clips and clamps secure parts without relying on full thread engagement.

In textiles and apparel, fastenings include buttons, zippers, hooks and eyes, snaps, buckles, and hook-and-loop closures. These closures balance strength, ease of use, wear resistance, and appearance, and are designed to withstand repeated opening and closing and washing.

Materials for fastenings range from steel and stainless steel to aluminum, brass, and plastics, with corrosion resistance and strength guiding selection. Design considerations include the type of load (tensile, shear, or combined), vibration, temperature, fatigue, and accessibility for installation and removal. Many fasteners conform to standardized specifications set by organizations such as ISO, DIN, or ANSI/ASME to ensure interchangeability and reliable performance across applications.