What Is a Socket Screw?

Socket Screw is a fastener that combines some of the increased performance features of hex screws and bolts with the convenience and ease of use of standard format screw sets. They’re especially popular in applications where the space to install a nut or bolt is limited, and they’re also frequently used as a permanent replacement for nuts on shafts.

Socket screws have a cylindrical head that has an internal hex socket (also known as an Allen socket) in which a hex key or wrench can be placed for tightening or loosening. The hex shape allows the socket to be placed over the end of a threaded shank, and tightening or loosening is achieved by inserting an Allen wrench into the socket and turning it clockwise.

The socket is surrounded by the head, which can be in one of several different styles. Flat socket cap screws, for example, are countersunk and lie flush with the surface beneath them, making them ideal for a smooth finish. Button or mushroom socket caps, on the other hand, have a protruding head that’s shaped like a button or a mushroom and allow for a secure fit in countersunk holes.

These fasteners generate a compressive load that holds parts underneath the cup – the concave section at the top of the head – resisting rotational movement and standing up to vibration. They’re often used in applications where components must remain fixed to the shaft, such as shaft collars or crash bars on exit doors.

In addition to the head type, other important factors when selecting a socket screw include its material composition and environmental conditions, as well as the load it’s required to carry. A metal that can stand up to abrasion, corrosion, high temperatures or other harsh environmental conditions is preferable. For heavy-duty loads, a socket screw with adequate tensile and shear strength is critical.

A hex socket screw’s ability to accept an Allen wrench makes it easy to install and remove. They can be used in locations where there isn’t enough room to maneuver a wrench or nut, and their low profile helps them blend in with other fasteners. They’re also a great choice for high-stress applications, such as mechanical assemblies and automotive applications. Using them instead of bolts and nuts can reduce the overall weight of an assembly, while also delivering superior torque and clamping force. This can make a major difference in the quality and durability of an application, particularly when working with thin materials.