Nature and Working Principle of Threaded Fasteners

Threaded fasteners are standardized mechanical components that utilize the mechanical principle of the helix (thread) to detachably join two or more parts. By engaging internal and external threads, they convert rotational torque into substantial axial clamping force, thereby providing reliable connection, fixation, and sealing; they are among the most widely used fundamental components in modern industrial assembly.

The core of a threaded fastener is the thread pair. Its working principle is based on the mechanics of the helical inclined plane: as a bolt (or screw) rotates, the helix angle of the thread converts rotational motion into linear motion along the axis, generating a preload force. This preload creates compressive friction between the joined parts, enabling them to withstand external loads such as shear forces, vibration, and impact.