Self-tapping screws are designed to create their own threads as they are driven into materials like metal or plastic. Self-tappers typically require a pre-drilled pilot hole
Types of Self-Tapping Screws
- Thread-Cutting: These have sharp points or flutes that remove material to create a clean thread, ideal for harder materials like sheet metal.
- Thread-Forming (Type B): These have blunt ends and displace material rather than cutting it, which creates a high-friction, vibration-resistant fit in softer materials like plastic.
The head type of a self-tapping screw determines how it sits on the surface (flush vs. proud).
Pan Head
- Best for: General metal fabrication and plastic.
- Why: It has a flat underside and a rounded top. It sits "proud" (on top) of the surface, providing a large clamping area without cutting into the material.
- Available in slotted and pozi drive types
Countersunk Head
- Best for: Wood-to-metal or where a flush finish is needed.
- Why: The head is conical and sinks into the material so nothing sticks out.
- Available in slotted and pozi drive types
Pozi flange
- Feature an integrated washer-like collar that spreads the clamping force over a wider area.
- This makes them ideal for securing thin sheet metal, vehicle trim, or brittle plastics where a standard screw might pull through or crack the material.
