These include socket screws for production, incorporating milled sides (cap heads), so they may be easily spun up by hand and, of course, with a recessed hex drive which enables machine feed and torqueing on the assembly line.
Other specialist socket screws include button head/dome head designs which give improved appearance, lower profile and a smooth finish. They also offer more clearance with less vulnerability to interference, either to clothing or to other equipment passing over and are ideal for floor fixings, as they present less of a trip hazard.
Socket head cap screws are generally more considered for engineering use at the elite end of the fastener range, by virtue of their more precise production tolerances - and historically, being more commonly of 12.9 grade, they are engineered for use at the top end of the precision spectrum.
In particular, the socket head shoulder screw variant features a plain shank with a ground surface for location – “a dowel with a thread”, especially useful for tooling applications where a lower clearance is desirable, e.g. for locating with precise fit, but it can also be used to provide a bearing surface.
