A screw is a threaded fastener characterized by a helical ridge wrapped around a cylindrical or conical shaft. It is one of the most widely used mechanical fasteners.
Structure & Principle
A typical screw consists of a head (for driving), a shank, and external threads. Unlike bolts, many screws can be driven directly into materials such as metal, plastic, wood, or concrete, creating their own mating threads or cutting into the material.
Key Features
Forms a removable or semi‑permanent joint
Transmits rotational force into linear clamping force
High resistance to loosening under vibration
Can be installed with or without a nut
Common Types
Wood screw: For joining wooden components.
Sheet metal screw: Used in thin metal sheets.
Self‑tapping screw: Creates its own thread when inserted.
Machine screw: Small, precise, used with a nut or tapped hole.
Drywall screw: Designed for plasterboard and light construction.
Applications
Screws are extensively used in furniture, electronics, construction, automotive, household appliances, and general assembly due to their convenience, versatility, and ease of installation.