Countersunk self-tapping screws are self-tapping fasteners with a conical countersunk head and a pointed tail. They are designed for a smooth surface and easy installation, allowing for self-tapping on materials that do not require pre-threaded fasteners.
The head shape is a 90-degree or slightly smaller conical shape. The design aims to ensure that the screw head fully sinks into or is flush with the workpiece surface after tightening, resulting in a smooth, non-protruding surface.
The thread start end is a sharp guide tip for easy initial positioning and material cutting. It self-cuts and shapes a matching thread into the material being fastened (such as plastics, thin metal sheets, wood, and composite materials).
The most common head type is Phillips head (PH), followed by slotted head. For applications requiring higher torque or anti-slip properties, Allen or Torx heads are also available.
The head can also be customized with ribs, typically six ribs, for anti-slip purposes.
Materials typically include C1022A carbon steel, stainless steel (such as 304 and 316, used in applications requiring high rust resistance), and copper.
Carbon steel offers a variety of surface treatments, such as galvanizing (white zinc, color zinc), nickel plating, blackening, and Dacromet coating, to enhance rust resistance and aesthetics.
Working Principle:
Positioning and Insertion:The pointed end is accurately positioned under pressure and penetrates the material during rotation.
Self-Tapping Forming: The sharp thread, like a tap, presses (for ductile materials) or cuts (for brittle materials) into the material's hole wall to create a matching internal thread.
Counterhead Locking: The screw is continuously tightened until the conical head is fully embedded and recessed into the tapered hole on the workpiece surface, achieving both fastening and surface flatness.
Outstanding Performance Advantages of Countersunk Head Screws:
Smooth and Aesthetically Pleasing Surface:** No protrusions after tightening, does not affect appearance, is less likely to snag other objects, and offers high safety.
Space Saving: Suitable for compact structures where protruding parts are not permitted.
Self-tapping convenience: Eliminates the pre-tapping process, improving assembly efficiency.
Reliable connection: The self-tapping threads create a tight fit.
Main application scenarios: Suitable for any application requiring a flat surface and substrate suitable for self-tapping:
Sheet metal chassis and cabinets: Used to fix side panels, covers, partitions, etc., and is a standard part in the sheet metal industry.
Furniture assembly: Especially for modern panel furniture (such as those using MDF or particleboard), often used in conjunction with pre-drilled guide holes to achieve concealed connections.
Automotive interior and parts: Used to fix plastic trim panels and interior components.
Plastic product assembly: Used to fix various plastic shells and parts (care must be taken to ensure the plastic's toughness to prevent cracking).
Advertising display equipment: Used to assemble aluminum alloy profiles, signage back panels, etc.
