Cap screws are fasteners that feature either internal or external socket drive heads, with different shapes depending on the type. Below the head, they have a fully or partially threaded shaft with a beveled end. These fasteners are commonly used in machinery, automotive, and industrial manufacturing due to their high yield strength and durability.

Different Types of Cap Screws and Their Applications

Type of Cap Screw		Head Shape	Drive Type	Application
Flat Head Cap Screws		Countersunk	Hex or Socket	Used where a flush surface is needed, such as in countersunk holes
Hex Head Cap Screws		Hexagonal	Hex or Socket	Heavy machinery and structural applications
Socket Head Cap Screws		Cylindrical	Hex Socket	Precision applications where space is limited
Button Head Cap Screws		Rounded	Hex or Socket	Where a low profile is needed or for aesthetic purposes
Pan Head Cap Screws		Rounded with a flat underside	Hex or Socket	General-purpose use where a large bearing surface is required
Slotted Hex Cap Screws		Hexagonal	Slotted or Hex	Applications where a slotted screwdriver is preferred
Torx Cap Screws		Star-shaped	Torx	High-torque applications
Low Head Socket Cap Screws		Low-profile cylindrical	Hex Socket	For applications with limited vertical space
Hex Flange Cap Screws		Hexagonal with a flange	Hex or Socket	Automotive and machinery applications
Tri-Wing Cap Screws		Triangular winged	Tri-Wing	Security applications

Flat head cap screws are manufactured according to ISO 4762 standard

Mechanical Properties and Grades of Socket Head Cap Screws

ASTM Standards of Cap Screws

• ASTM F835 (Alloy Steel Flat Countersunk and Socket Button Head Cap)
• ASTM F912M (Alloy Steel Socket Set Screws (Metric))
• ASTM F912 (Alloy Steel Socket Set Screws)
• ASTM F837M (SS Socket Head Cap Screws (Metric))
• ASTM F837 (SS Socket Head Cap Screws)

Round socket head screws are available in a wide range of sizes

Also known as round head cap screws or circle head screws, these fasteners are extremely useful in various applications. They are often used in electronics, construction, carpentry, and fastening thin materials. Due to their unique shape, they offer a secure and durable connection, making them ideal for many industrial and mechanical uses.

They are also known for their toughness and can be used as security fasteners. Without the proper tools, it can be difficult to install or remove them. In construction, they are cost-effective and provide good value for money. In carpentry, they are easy to use and suitable for woodworking projects.

Socket Cap Screw Sizes as per ASME B18.3

Hexagon Socket Head Screws Size Chart (BS 2470)

Check dimensions and tensile strength of button head cap screws

It has the similar shape of a pan head with the driver of a socket head. It is manufactured for fastening applications, it doesn’t have strength like standard socket screws. The socket driver is perfect for low withdrawal applications which needs a large area of clamping face.

Moreover, the button heads socket drive gives higher strength than a standard phillips which gives fitting in tight area. It has low domed head with a broader bearing surface heads, which offers a finished look. It is ideal choice when accurate appearance is required.

Button Head Cap Screws Dimension