Self-Tapping Screws

Self Tapping Screws are designed to tap threads into a pre drilled hole. These screws are often called "sheet metal screws" but do not need to be used purely in sheet metal. The tapping thread design can be used in wood and plastic as well.  Most screws in general are self tapping, but the screws below can be used in various material applicatoons. Unlike wood screws, which also tap a hole, wood screws should only be used in wood.  Concrete screws tap threads in a hole, but can only be used in concrete. 

Self tapping screws / sheet metal screws are most often confused with self drilling screws.  Self drilling screws have a drill bit point on the tip of the shank. 

High-Low - For use in plastic, nylon, wood or other low-density materials. Thread design reduces driving torques, enhances resistance to thread stripping, improves pullout strength and lessens the risk of cracking the work piece.

Type AB - (Fine Thread) Designed for use in the thinner sheet metal commonly used today, particularly in appliances. 

Type A - (Coarse Thread) For self starting in thin (.015" to .050" thick) metal or resin-filled plywood. Hex Washer Heads are commonly used to hold license plates into plastic. 

Type B - For molded or through holes in thin metal, non-ferrous castings. Blunt Point.