Skruvar

Skruvar are fasteners widely used to join materials by converting rotational motion into linear force. A screw consists of a cylindrical shaft with helical threads and a head that accepts a driver. As the screw is driven into a material, the threads grip the surface and create clamping force, holding parts together.

There are many types of skruvar, differing in head shape, drive system, thread form, and material. Common head shapes include flat (countersunk), pan, round, and hex. Driving options range from slotted and Phillips to Pozidriv, Torx, and square drives. Thread forms distinguish wood screws, which have coarser threads and often a tapered shank for better grip in wood, from machine screws, which use uniform threads with nuts or tapped holes in metal.

Materials and finishes vary for different environments and performance needs. Skruvar are commonly made of carbon steel or stainless steel; brass and aluminum are used for specific properties such as non-magnetic or lighter-weight applications. Coatings such as zinc plating, galvanizing, or black oxide improve corrosion resistance and appearance.

Standards regulate dimensions, threading, and compatibility. Metric sizes use designation like M6 with a specified pitch, while imperial sizes express diameter and threads per inch. Standards from ISO, DIN, ANSI/ASME, and JIS help ensure interchangeability and reliable performance.

Applications span woodworking, cabinetry, furniture assembly, metal fabrication, and construction. Selection depends on substrate, load, environment, and required strength. Installation generally involves appropriate pilot holes for wood screws, correct driver type and torque, and attention to alignment to avoid cross-threading or overtightening. Regular maintenance includes inspecting for corrosion and replacing worn or incompatible screws.