Self-tapping screws are known for their ability to drill their own hole as they go along, as opposed to drilling a pilot hole like with flat-ended screws. They can have a sharp or blunt tip. A sharp tip is usually for drilling into softer materials, such as wood or plastic, without having to drill a pilot hole. The blunt tip helps your success rate when drilling into something harder, like metal. Self-tapping zip screws are especially useful for projects involving metal buildings or gutters, for example.

With thin wings wider than the thread formed behind the self-drilling head, the winged self-tapper will cut a clearance hole in soft materials like wood or plastic. Be aware, though, that they can be destroyed by materials which are more robust, such as metal. The Drywall Screw

What's the difference between a self-tapping screw and a self-drilling screw?

Selecting the correct threaded fastener (self-tapping screw) to suit the material is critical as it directly impacts drive to strip torque ratio and clamping retention. The table under section material stiffness should give a starting point in screw selection using the material stiffness. Types of self-tapping screws for plastics (Credit:stanleyengineeredfastening.com)

Every type of plastic has unique performance difficulties, such as ductility, thermal expansion, and clamp retention. Choosing a fastener that best meets these characteristics is essential to a successful screw joint in your product designs. Thread forming screws for plastic doesn’t have a pointed tip and would need a pilot hole. Screw thread deforms the plastic material to flow around the screw threads. Hence the overlapping amount (thread engagement) and thread profile angle are crucial. Thread forming screws for plastic (Credit:stanleyengineeredfastening.com) The advantage of self-tapping screws for aluminium is that they don't need pre-drilling and are easily removed without damaging the metal. They can also be reused in the same material. Forced under pressure into the material you’re using, Type U metallic drive screws have spaced spiral threads and a blunt tip – and while this type of screw is considered permanent, others can be easily taken out. The Winged Self-TapperIf the letter ‘B’ in a screw’s designation – for example, type AB or B – has spaced threads, while if the ‘B’ is absent (for instance, Type F), machine screw threads are present. Having said that, there are two exceptions, with Type A having spaced threads, and Type U (metallic drive screws) featuring spaced spiral threads. It’s worth knowing that while Type A is still available, it can be harder to come by. Thread forming and thread cutting screws are available in flank angles of 30⁰, 40⁰, 45⁰, 48⁰ & 60⁰. Some brands also do dual spaced threads and trilobular shapes. Plastic: The technology associated with self-tapping screws for plastic has evolved to the point that the pieces are now specialized and sometimes made of plastic themselves. Self-tapping screw technology has evolved to include more lightweight materials such as plastic and aluminum and shorter thread engagements. Self-tappers are often used in sheet-metal applications where one-sided access is an issue. This might be applicable in automotive, aviation and other industries. The technology has overcome what used to be a challenge for many industries — fastening together thin metal safely with a screw. Self-tapping screws are used for a wide range of applications involving steel and aluminum, as well as alloys and mixed applications. They handle metal gauges from about 24 through 30.