ASME/ANSI B18.3 Hexagon Socket Head Cap Screws

ASME/ANSI B18.3 Hexagon Socket Head Cap Screws feature a cylindrical head with a recessed hexagon socket, providing a compact fastening solution where conventional external-head bolts may require more installation space. The internal hex drive allows the screw to be tightened from above with an Allen-type wrench, making it suitable for assemblies where access around the fastener head is limited.

The socket head design provides a relatively small head diameter while maintaining a substantial bearing area and robust head section. This makes Socket Head Cap Screws well suited to machine components, tooling, fixtures, equipment assemblies, and other compact mechanical connections where strength and space efficiency are important. For selection, customers should consider the nominal diameter, screw length, thread series, material, strength grade, hardness, surface finish, and available tool access to ensure the screw matches both the joint requirements and installation conditions.

Specification:

ASME/ANSI B18.3 Hexagon Socket Head Cap Screws are specified by their nominal diameter, thread series, length, head dimensions, and internal hex socket dimensions. The cylindrical head provides a compact radial profile, while the recessed socket allows the fastener to be installed without requiring access around the outside of the head. These dimensional relationships are important when the screw is installed in a confined machine or tooling assembly.

For material selection, alloy steel and stainless steel versions serve different mechanical and environmental requirements. Alloy steel is generally selected when high tensile and clamping strength is required, while stainless steel is preferred where corrosion resistance is a primary consideration. The applicable material and property specification should therefore be confirmed together with the required screw size and grade.