Thread rolling screw recommended for use in metal. Self-tapping screws can be divided into two classes, those that displace material (especially plastic and thin metal sheets) without removing it are termed thread-forming self-tapping screws; self-tappers with sharp cutting surfaces that remove the material as they are inserted are termed self-cutting.
Thread-forming screws may have a non-circular plan view, mostly with three-fold symmetry for Taptite screws.
Thread-cutting screws have one or more flutes machined into their threads, giving cutting edges.
