Socket head cap screws are used for applications with limited space. They have cylindrical head and internal wrenching features (mostly hexagon socket) that allow them to be used in locations where externally wrenched fasteners aren’t desirable. They are used for critical vehicle applications, machine tools, tools and dies, earth moving and mining machinery, and a wide range of engineering applications. The most important reasons for the increasing use of socket head cap screws in industry are safety, reliability and economy.
The original configuration of socket head cap screws didn’t maintain consistent relationships among the nominal shank diameter, head diameter, and socket size throughout the available size range. This limited the performance potential of some sizes.
Advantages of socket head cap screws
As compared to ordinary fasteners, less socket screws of the same size can achieve the same clamping force in a joint.
As fewer screws are required for a given job, fewer holes are required to be drilled and tapped.
There is weight reduction as fewer screws are used.
There will be weight reduction on account of smaller size of the component parts since the cylindrical heads of socket screws need less space than hex heads and require no additional wrench space.