ruuvit

Ruuvit are fasteners used to join components by engaging a helical screw thread. In Finnish, ruuvi means screw, and ruuvit is the plural form. Screws are driven into a substrate or into a pre-tapped hole, or into a matching nut, converting rotational motion into linear clamping force and enabling disassembly.

Ruuvit consist of a head, a shaft, and a threaded portion. The head provides a drive interface, while the thread or mating thread holds the components together. Common materials include carbon steel, stainless steel, brass, and plastics for specialized screws. Coatings such as zinc, galvanization, or black oxide improve corrosion resistance and durability.

Types include wood screws, machine screws, self-tapping screws, self-drilling screws, sheet metal screws, lag screws, and masonry screws. Drive styles vary as well, including slotted, Phillips, Pozidriv, Torx, or hex. Heads may be flat/countersunk, pan, round, or hex, chosen to suit load, aesthetics, and mating parts.

Sizes and standards are expressed by diameter and length in metric (M) or imperial units. Metric screws use ISO and DIN standards (for example M4 x 0.7). Machine screws and bolts follow ANSI/ASME or DIN specifications. Thread pitches, tolerances, and loads determine fastening suitability for wood, metal, or masonry applications.

Design and installation considerations include selecting the appropriate length for adequate thread engagement, choosing the correct drive and head style, and controlling torque to achieve the desired preload without stripping threads. Pre-drill pilot holes for hard substrates; use washers where needed; and avoid cross-threading to ensure reliable performance and removability.

Ruuvit, the Finnish term for screws, are a fundamental fastener family used across construction, manufacturing, and consumer products. They differ from nails by threading properties and removal capability, and from bolts by typically engaging a nut or threaded reservoir rather than being driven with a nut alone.