Hexagon socket button head screw

Understanding the Button Head Geometry

The Hexagon Socket Button Head Screw is distinct from the standard Socket Cap Screw (DIN 912) due to its head geometry. The "Button" head is wider and flatter. This design is primarily chosen for two reasons: clearance and cosmetics. When vertical space is restricted, or when a fastener is exposed on the outside of a machine guard or panel, the button head offers a sleek solution that blends into the surface profile better than taller fasteners.

Mechanical Load Limitations

Reduced Loadability (ISO 7380): It is critical for engineers to understand that button head screws are generally not designed for high-strength structural applications in the same way as cylindrical cap screws. Due to the reduced head height and smaller internal hex drive size, they cannot withstand the same high torque values or tensile loads as a DIN 912 screw of the same diameter. Application Guidance: Regardless of the material (whether steel or stainless), button head screws are typically intended for holding covers, panels, brackets, and guards where the primary forces are shear or light tension. They should be used with caution in critical high-stress joints where bolt stretch is required.

Quality Assurance

At Fastener Core, precision is our standard. We can provide an EN 10204 3.1 Material Certificate upon request to verify the dimensional compliance and material composition of your order. Please note that third-party inspection services are available for an additional fee.

Common Industrial Applications

Due to their smooth finish and low profile, these screws are widely used in:

• Automotive Styling: Body kits, interior panels, and engine bay aesthetics.
• Public Furniture: Park benches and bus stops where sharp edges could cause injury to the public.
• Electronics: Computer cases and server racks where internal clearance is tight.
• Machinery Guards: Fastening protective covers where a snag-free surface is a safety requirement.

Frequently Asked Questions

Why do button head screws have a smaller hex drive than cap screws?

Due to the low-profile dome shape, there is physically less metal depth in the head to accommodate a deep socket. To maintain head strength, the hex key size (width across flats) is typically one size smaller than a standard DIN 912 cap screw of the same thread diameter. For example, an M6 button head often uses a 4mm key, while an M6 cap screw uses a 5mm key.

What is the risk of over-tightening button head screws?

The risk is "rounding out" the socket. Because the internal hex drive is shallower and smaller than standard cap screws, it is much easier to strip the drive if you apply excessive torque. It is essential to use the correct torque settings specified for ISO 7380 screws, which are lower than standard structural torque values.

Are button head screws suitable for flush mounting?

Button head screws are designed to sit on top of the surface with a low profile, not flush with it. If you require a completely flush finish where the screw head does not protrude at all, you should use a Countersunk (Flat Head) Socket Screw instead.