Below is a list of Self Tapping Screws manufacturers from Alsip, Illinois. Self tapping screws have the ability to form internal female threading into the materials in which they are being drilled. Many screws cannot be inserted into a material unless that material is “tapped” first. Tapping is the process in which a tap, which can be a drill bit or larger industrial tapping tool, is used to create the equivalent of female threading in a material. A threaded fastener can then be screwed into the threading.