Self drilling screws made of hardened carbon steel or stainless steel are used for fastening . Classified by the pitch of thread, there are two common kinds of self drillingl screw threads: fine thread and coarse thread. A self-drilling screw is a type of self-tapping screw that also features a drill point. The sharp drill point will both drill a hole and form the mating threads in a single operation, that can tap its own hole as it is driven into the material. More narrowly, self-tapping is used only to describe a specific type of thread-cutting screw intended to produce a thread in relatively soft material or sheet materials, excluding wood screws. Other specific types of self-tapping screw include self-drilling screws and thread rolling screw Meanwhile, There are collated self drilling screws. They can be used on screw gun, which speeds up the installation. Moreover, there are various coated self drilling screws which can protect against corrosion.Self drilling screws have a point that acts as a drill bit and sharp cutting threads that tap the hole during installation. Self drilling screws are a commonly used variety of screw for quick drilling into both metal and wood. A self drilling screw can typically be identified by its point and flute (notch) tip