Screws

Sonfast Corporation is a distributor and importer of all types of screws including screws used in construction and all types of assembly. Screws come in all sizes and configurations to accomplish a broad variety of assembly considerations. Screws can be used in plastics, steels, aluminum, brass, wood, concrete, and composite materials. Sonfast specializes in screws designed for use in plastics (Sonplast, Plastite, Hi-Lo Screws, Plastiloc, Plask, and many others) and can support customer engineering needs to design the right screw for plastic bosses or holes. Screw types include: "A", "AB", "B", "23", "25" "U-Drive", "17", deck screws, wood screws, thumb screws, furniture and cabinet screws, and many other types.

Wikipedia offers this definition of screws: "A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder, or shaft. Sometimes the screw thread mates with a complementary thread, known as an internal thread, often in the form of a nut or a object that has the internal thread formed into it. Their most common use is to hold objects together or locate objects.

Oftentimes screws have a head, which is a specially formed section on one end of the screw that allows it to be turned, or driven. Common tools for driving screws include screwdrivers and wrenches. The head is usually larger than the body of the screw, which keeps the screw from being driven deeper than the length of the shaft and to provide a bearing surface. There are exceptions; for instance, carriage bolts have a domed head that is not designed to be driven; set screws do not have a head larger than the shaft; and J-bolts don't have a head and aren't designed to be driven.

The majority of screws are tightened by clockwise rotation, which is termed a right-hand thread. Screws with left-hand threads are used in exceptional cases, when the screw is subject to anticlockwise forces that might undo a right-hand thread.