There is a type of self-tapping screw which is known as the thread-forming screw. They are defined as those types of screws that are usually made to use when the surfaces involved are plastics. Thread-forming screws are the type of self tapping screws that are devised to staying one given place very firmly. The drawback of this type of screw is that if there is too much on tension applied to the screw for tightening then the screw tends to result in breakage inside materials that is being used due to the pressure applied. Thread-cutting screws are chiefly used for wood and metal.