A screw is a fastener in the form of a rod with a special external thread, a threaded tapered end, and a head at the other end that forms a thread in the hole of the wooden or plastic product to be joined. The special thread has a pointed triangular profile and a wider flute width than the tooth width.
A screw is the most common type of fastener used in construction and finishing work. It is indispensable for mounting drywall sheets on a metal or wooden frame. Different types of screws are used for roofing and facade work, and for joining metal sheets. The structure of the slots and screw heads does not differ from that of similar screw elements. Plumbing screws have a hexagonal head.
Self-tapping screws are self-tapping screws that have a special external thread and a pointed end or drill tip that allows the screw to be driven into hardwood, plastic and metal sheets without first drilling a hole. Self-tapping screws are available in fine thread for wood and plastic and in coarse thread for metal. Shapes of screw heads: flat, convex, semicircular, countersunk, semi-countersunk, cylindrical, hexagonal, countersunk, looped, half-looped. Types of head slots: straight, cross (Ph or Pz), internal hex, Torx. The roofing screws are available in painted colors (up to 18 colors) with a hexagonal head, washer and rubber gasket.
Here you can find out about all standard types of bolt, screw and screw heads