tapskruvar

Tapskruvar, known in English as self-tapping screws, are fasteners that are designed to cut or form their own mating threads as they are driven into a material. They are commonly used to join metal parts, such as sheet metal, as well as plastics and some soft materials, without the need for a pre-threaded hole.

There are several subtypes of tapskruvar. Thread-cutting screws form threads by cutting into the material as they advance, while thread-forming screws displace material to create a tight joint without removing material. A related category, self-drilling screws, includes a drill-like tip that creates a hole while the screw is inserted, reducing the number of preparatory steps needed.

Construction and design features vary to suit different applications. Heads are available in many shapes, including pan, flat (countersunk), and hex, with drive types such as slotted, Phillips, Pozidriv, and Torx. Materials commonly include carbon steel, stainless steel, and alloy steels, with coatings such as zinc or nickel for corrosion resistance. The thread profile, pitch, and diameter are chosen based on the base material and required holding strength.

Installation considerations are important for reliability. In many materials a pilot hole is recommended or required, with hole size chosen to balance drive torque and pull-out resistance. Over-tightening can strip softer materials, while too little torque may result in poor clamping. Self-tapping screws are valued for quick assembly and removed/reused with moderate difficulty, but they may not be suitable for projects requiring precise, reusable threads.

See also: self-drilling screws, thread-forming screws, thread-cutting screws, and traditional wood or machine screws.