The steel thread cutting screw has a black oxide finish, a Type 23 point style, and a hex washer head. The screw, also called a type T thread cutting screw, has fine threads and a type 23 point that tapers down to a blunt edge and directs chips out of the hole to prevent clogging. The large cutting surface is suitable for soft metals and enables screw installation with minimal rotating force. Steel is often used in applications where strength is the primary consideration. The black oxide finish offers mild corrosion resistance and lubricity. The hex washer head has six flat sides that a wrench can grip to turn from the side, enabling use when there is no space above the head for a screwdriver. The flange acts like a washer to increase the fasteners bearing surface and distribute the clamping force over a larger area, providing grip and reducing damage to mating surfaces.
Thread cutting and thread rolling screws, two types of self-tapping screws, are threaded fasteners that create a mating thread in the wall of a hole. The two screws differ from each other in the way that they create the threads. Thread cutting screws cut the wall of the hole to create the thread, creating material chips that need to be cleared away from the hole to prevent clogging. Thread rolling screws, also called thread forming screws, do not remove material but instead press against the wall of the hole to displace the material and form the threads.