No Matter what you may call them, a Self Drilling Screw is a time saver! Self Drilling screws feature a distinct flute or drill point at the end of each screw, as well as self tapping threads to turn a three-step installation into one quick job. The TEK drill point, as well as the self tapping threads of the screw eliminate the need for pilot hole drilling and hole tapping before screw installation. Self Drilling Screws are used primarily when fastening into steel or other metals, and are typically used to join materials like sheet metal. Self Drilling Screws are primarily made of harder metals, or treated to make the material harder. Typical materials include hardened Zinc Plated Steel, and 410 Stainless Steel. This is to ensure that the drill point is a harder metal than that into which the screw is being installed. 410 Stainless Steel is ideal for Self Drilling Screws because it maintains the corrosion resistant properties of standard 18-8 Stainless, but can be heat-treated up to 40 Rockwell C. This is why self drilling screws are commonly used in roofing applications in combination with a watertight neoprene sealing washer, and for attaching metal roofing and siding panels to metal stud framing.
Not All TEK Screws are Created Equal
The distinguishing drill point of a Self Driller is what makes them unique, however these points come in different lengths for different applications. The Drill Point of one of these screws is given a TEK number, which can be determined by the length of the flute. TEK points are available in TEK 2, 3 and 4-5. The typical 25 to 16 gauge metal will require the use of a TEK 3, but 14 gauge and below will require TEK 4-5. This is why TEK 5 screws are used for fastening into structural steel. As a general rule of thumb, the higher the TEK number (the longer the drill point), the thicker the metal. It is fundamental that the point is high enough on the TEK scale to pierce the metal being drilled into.